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Posted by: lsintampa Dec 22 2014, 08:53 AM

75 2.0 FI

I'm in Florida - so the weather outside is somewhat warm (50's maybe right now).

I'll try to be as detailed as I can. I've had this issue since I started driving the car - about 8 months ago. It underwent a motor rebuild - along with some other mechanical repairs.

All hoses are new (air supply, and fuel). ECU and other FI components are original - best I can tell.

When I start the car - it starts right up. At idle RPMs go to about 1500 with a very slight surge (maybe 1450 - 1550).

If I pull the air supply that goes to the AAR from the air filter and plug it, the idle goes down to what I'd expect - about 900 RPM still with a little surge. This is while the motor is "cold" - so to speak. Within like a minute of starting.

As the car warms - just at idle, the RMPs start to come down and the vacuum from the AAR isn't as strong - but still present. However now the surge is crazy - like from almost a stall up to maybe 1200, back down, back up, etc.

Pulling the hose from the AAR - does nothing - I can plug it or leave it and the air filter wide open and there is no change. I put the hose back on - again no change.

I did not let it get to a full warm state - IE the temp gauge just started to move up.

I've heard there are three states (cold, pre-warm, and fully warm) that come into play.

Various tinkering, like turning the air mixture valve to a total closed state, and mucking with the ECU dial has had some success, but at BEST, I get like a 1200 RPM idle still with some surging.

To the best of my knowledge there are no air leaks - at least not from any hoses.

I've some concerns that the air plenum may have some stress cracks around the support studs. But I don't know that would cause the surging? I'd think the idle would just be high - period. YES / NO?

I don't know where to begin to figure out why it behaves this way.

Thanks,

Len

Posted by: 76-914 Dec 22 2014, 09:19 AM

"To the best of my knowledge there are no air leaks - at least not from any hoses."

Well, you need to "know" because your the mechanic. I chased this same scenario for months before I found one of the new injector seals had not sealed because I inserted the injector at an off angle so to speak. Once that was addressed I found that the MPS was also out of tune since the rebuild. Installed an AFR gage, tuned the MPS and all was great.

EDIT-Pull that plenum and inspect it. Pour some liquid into it to see if there are any leaks at suspected areas, check intake runner hoses, oil filler gasket, throttle shaft for excessive wear. Also, disconnect everything from the vacuum source except the MPS. If it runs better re-attach each item, one at a time until you find it.

Posted by: JawjaPorsche Dec 22 2014, 10:27 AM

Oil filter gasket. Does any vendor sell this? I did not see it on 914Rubber website.

Thank you in advance for your response.

Merry Christmas!

Posted by: BeatNavy Dec 22 2014, 11:02 AM

I've had similar symptoms (crazy up and down surge) when the vacuum line to my PCV valve is disconnected or not sealed tightly. 914Rubber does sell that gasket. You're talking http://shop.914rubber.com/914-Oil-tower-gasket-914OTG.htm, right?

Posted by: lsintampa Dec 22 2014, 11:23 AM

Well, here's an odd one for you all to ponder.

I adjusted the throttle valve switch - per the Pelican instructions - had no effect.

So with the motor warmed up now - AAR is shut down, for kicks I pulled the hose off of the MPS leaving it open to the plenum.

Would you know it, the surging stopped instantly, and plugging the hose only dropped the idle a bit more.

No clue what that means - other than the MPS is not working correctly???

Posted by: JawjaPorsche Dec 22 2014, 12:05 PM

Thanks for responding. I have replaced that one. Is there a gasket for the screw on top?

Posted by: BeatNavy Dec 22 2014, 12:40 PM

Oh, do you mean the sealing ring, number 1 below (Part Number: 021 115 137)?

Yeah, that seems to be NLA all over.

Posted by: JawjaPorsche Dec 22 2014, 12:48 PM

Might be a gasket 914Rubber will consider making for us. Fingers Crossed!

Posted by: Philip W. Dec 22 2014, 01:00 PM

its either a vac leak you have not found OR you are still running lean so ild will be high, and if it goes lower it will start to surge.
lean running, could be CHT issue and/or MPS but probably with MPS - is the MPS a stock original?( they tend to be a bit on the lean side) - oh, then of course re-verify your timing if you have not already.

pw

Posted by: lsintampa Dec 22 2014, 01:02 PM

Checked timing... maybe you missed my last reply - If I pull the hose off of the MPS - the car seems to idle just as I'd expect. Put the hose back on and the surging kicks right in.

Posted by: BeatNavy Dec 22 2014, 01:08 PM

Another case of a car running better without the MPS??

If that's the case, then you probably are running super lean due to some major vacuum leak and removing the MPS is making the mixture "acceptably" richer to compensate.

The only time of had that kind of surging is when I've forgotten to reconnect a hose or make sure it was tight.

Posted by: r_towle Dec 22 2014, 01:09 PM

its a vacuum leak

Posted by: Philip W. Dec 22 2014, 01:16 PM

yes- i admit, jumped to the reply before reading down thru all of the responses-


maybe- and a bad vac leak like rich suggested could dot his - in my case recently it's the MPS gone bad electronically, making it SUPER lean, so disconnecting the mPS makes it default rich, but in this case still run

Posted by: BeatNavy Dec 22 2014, 01:24 PM

Phil, from what I recall on yours you solved it with a spare MPS, right? Did you test the continuity at primary and secondary coils (terminal pairs) and still get acceptable readings (i.e., did you verify the MPS failed by testing it or by discovering that a replacement MPS worked)?

Posted by: lsintampa Dec 22 2014, 02:05 PM

Well, it's about as good as I can get it.

Everything hooked up, when warm.. the idle surges between 1100 and 1200. High but if I try to get it any lower it just gets worse.

It will need to do for now until I find someone that knows how to figure it out.

I can do a bit - follow directions, etc., but I'm no expert for sure.

As far as vacuum leaks, about the only thing I can suspect would be the plenum. I checked the FI seals (all new) - reseated them. Just about all the other seals are new - as are the hoses.

Not sure if it matters, but the car WAS from CA - and had other parts that are long gone. Not sure if it had a speed limiter or not - I have the resistor pack that I think went with. The FI harness is from a 2.0 D-Jet - NON-CA car. Maybe something to do with it?

I've had one issue after another - trying to get this car settled down. Little seat time, but what time I've had has been GREAT. The issue only shows up at idle - car runs great - doesn't cut out, no issues with any backfires, misses, etc.

I think I'll enjoy it for a bit and drive it. Maybe when I get up enough energy to take the plenum off (again), I'll check it out.

Posted by: Philip W. Dec 22 2014, 02:23 PM

kind of , yest - tried the spare and the car started and runs, albiet still on the lean side - and ses tested the termial pairs and they tested o.k.( 92 and 330 ohms on static ). - My mechanic put his hand pump vac withmeter on it( the old one) while running but vac line off of it, so it was running but super rich and began to draw pressure and only got to 5mmhg and it killed it, AF meter wen super lean that fast. - - which appears to indicate that electronics inside were somehow bad, not the diaphragm. btw that unit had nevere been opened but a p.o. had drilled a hole thru the epoxy plug and cap to access the center screw to adjusted it, so i think it may have been going bad for a while and maybe that was able to compensate-for a while at least. and one thing i had not done was to test that resistance under a load . i just assumed that it was o.k. becasuse it was good static and held vac.

Posted by: saigon71 Dec 22 2014, 02:31 PM

Have you replaced your TPS board with a new one?

My 74 2.0 D-jet had the same issue. After verifying that I had zero vacuum leaks, timing/dwell spot on, good MPS, new CHT with correct part number and adjusting TPS per Pelican article...I still had the same problem.

I bought a new TPS board from Dave Sprinkle, a member on this forum, installed it and calibrated it according to the Pelican instructions. It fixed the idle surge. Car now idles perfectly throughout the entire warm-up cycle.

Posted by: r_towle Dec 22 2014, 02:35 PM

Best test is to go to the hardware store and buy an assortment of rubber caps.
Remove every line from the plenum (after the car is warm) and cap them with the tight rubber caps.
See if idle stablizes.

I ran into this early on in my car, so over 10 years ago.
I found that the manifold to intake runners develop a slight vacuum leak.
I now put them on with RTV gasket at the head side and at the manifold side and I let it setup overnight before running the motor, leak gone.

I also round leaks at the decel valve (I removed it forever)
I found leaks at the AAR valve, (removed it forever)

From there I found that there is only one way to set the TPS properly, and there is no possible variation. It must sit in a certain position at Idle, or its wrong.

If its wrong at idle, it surges, but it also makes the car run wrong all over the place, but its hard to notice except at idle when it surges.

Oh, one more thing I found was the distributor advance plates need to be cleaned and lubed because they have 40 year old grease that now behaves like glue when hot...and when the advance plates do not snap back to zero advance, the car surges at Idle.


Let me see if I have the pic

rich

Posted by: r_towle Dec 22 2014, 02:38 PM

Here


Attached image(s)

Posted by: r_towle Dec 22 2014, 02:40 PM

sorry, had to get it off my phone.

See the middle brass contact finger?
See how it is touching nothing?
That is what it must look like at idle.

The one one the left sits on the first leg.

I found it alot easier to remove the throttle body along with the TPS and set it when its not in the car, so you can see everything clearly.

Rich

Posted by: lsintampa Dec 22 2014, 02:54 PM

If you are talking about the one with the blue arrow pointing to it, that seems to be on something? I'll have to pull that puppy off and take a look.

Posted by: r_towle Dec 22 2014, 02:56 PM

the reason the TPS can be adjusted is it was made for a large number of cars.
At the end of the day, it can only be positioned ONE way to work on a given throttle body.

The idle circuit is a special circuit in the ECU, so it needs to have the TPS in the correct position in order to make that special circuit activate.

Posted by: The Cabinetmaker Dec 22 2014, 02:58 PM

Does the idle mixture screw on the ecu make any difference?
Have you verified dwell and timing?

Posted by: lsintampa Dec 22 2014, 04:06 PM

Dwell and timing were checked a while back. No big changes to think they are off, but I can check it again.

ECU adjustments .... I've turned that thing all the way in one direction and the other. Seems to make no difference. I don't know how sensitive that ECU adjustment is, but it seems to me that it really doesn't do much.

I removed the Throttle Body and adjusted the switch using the Pelican method. At full CCW it reads 1 OHM, then I turn clockwise to Zero, then ONE more notch - OHM meter is still at ZERO at that point. Didn't seem to do much.

I opened the air valve on the TB so my idle goes up to like 1500 RPM. At that speed, the surge is minor, but still present. Seems to get really wild (surging) when I try to turn in the air valve on the TB - the lower the RPM the worse the surge.

IDK, It would be nice to figure out. I'm just not in the mood to yank the whole system out to check that plenum. I still think (and I'm most likely wrong) that if there were a air leak, the idle would just go high. Something I don't understand is going on. (as he states the obvious)

Posted by: The Cabinetmaker Dec 22 2014, 05:00 PM

The idle mixture knob will work only if the tps is correctly set. Your tps board is crap. Contact Dave sprinkle for a new board. They can ohm correctly but still not work.

Posted by: Philip W. Dec 22 2014, 05:09 PM

I was still having a bucking at 2800-3000 rpm and issue with not having a steady idle. I had replaced the board a few years ago with one of Dave's but it did go bad too. I got a very lightly used original tps from Bruce stone and both of those issues are now gone completely and once the tps was put in right place- I used the picture that rich posted above, the ecu know will increase or decrease your mixture and effect your idle for sure. I think I counted 22 or 23 clicks so put in the middle and start from there.

Posted by: r_towle Dec 22 2014, 05:11 PM

Before you buy anything, please LOOK at the TPS as mounted, at idle, with the cover removed.

Posted by: r_towle Dec 22 2014, 05:23 PM

Here is one

http://www.914world.com/bbs2/index.php?showtopic=70988&hl=advance++plates++cleaning


Someone did a thread with pictures that may help more if you find it.


This
http://www.914world.com/bbs2/index.php?showtopic=94299&hl=advance++plates++cleaning

Posted by: The Cabinetmaker Dec 22 2014, 06:46 PM

I have gotten a few years extra life from a tps by sanding the traces on the board with 2000 grit wet or dry, then cleaning with lacquer thinner

Posted by: lsintampa Dec 23 2014, 10:20 AM

Well, here are two shots of how the throttle switch is set.

I've not tried this setup yet, as I just took the TB off to set it.

I'm thinking it's right on - but I don't know for sure.

In any event, I'm going to give it a shot.

And so it goes.

Posted by: lsintampa Dec 23 2014, 10:49 AM

If the middle finger is "touching nothing" about the only way I could get it there was to take the TB off the car, then used a OHM meter to insure the finger was not touching the "brass tracers".

The pictures I just posted - the middle finger WAS still touching. So I made just a slight adjustment - used the OHM meter to insure it was not touching and installed that into the car.

To be honest, the surging is now worse than it was.

Question... would the Dizzy vac be suspect? Or the Dizzy advance plates?

The Dizzy is original - just new points / condenser....

The other suspect is still the Plenum.

Onward through the fog....

Posted by: Philip W. Dec 23 2014, 10:53 AM

when i went thru this first time, i did have leak at the plenum and at the throttle body, and put on new hoses for the intake runners-to-plenum, but those still leaked, so i put clamps on those and now no vac leaks at the TB, plenum or intake runners.
test by spraying a bit of water mist or some use carb cleaner- that will richen and change your idle if it is leaking.

Posted by: r_towle Dec 23 2014, 11:37 AM

YES
YES

clean the distributor advance plates, I believe I posted a few threads above in this thread....go look at that.

IF you are diagnosing, take your time to see if you are doing something worthwhile.
So, when you take apart the advance plates, take your time, do they move and spin freely in your hand before you seperate them, or is there friction and binding???

Try to note the before and after condition so next time it happens, you know.

BTW, if the advance plates have never been cleaned, they will bind and in some cases be very hard to move, even cold.
When you grease them and clean them....you will be amazed how easy they move.


rich

Posted by: lsintampa Dec 23 2014, 12:09 PM

Well carrying on with the experiment....

Since the last setting of the TB switch caused the surge to get worse, I went back to old school and adjusted it using the Pelican method, and now the surge is much improved, but still persists.

That in itself has to be a clue ?? or not, I guess.

I'm gonna try the carb cleaner trick - poke about the fuel runners, plenum, etc. See if there is some suction happening where it shouldn't.

I'm beginning to think that perhaps the dizzy may be the next component to inspect.

But as it pertains to the dizzy, I'd think if the advance / retard were not functioning correctly, I'd have issues while driving up and down the RPM range. Car runs fine at speed, so that's why I've not suspected that the dizzy was suspect. Can't hurt to check it out though.

Posted by: lsintampa Dec 23 2014, 12:57 PM

Maybe I'm onto something here....

I don't have any carb cleaner, but I do have starter fluid and a fire extinguisher

With the idle surge as good as I can get it, I started up at idle and started spraying about areas where no air should enter.

Left side fuel runners - nothing - no change. Right side however did change the idle. At first I thought it might be the fuel runner gaskets, but I don't think so.

The runner gaskets, manifold gaskets, TB gasket, all are new, as are the injector seals. So I don't think that's the issue.

HOWEVER, I do now suspect the plenum itself is an issue. I had asked this once before, but I wasn't really sure if my question was understood.

Simply put, there are two support tubes (columns) that support the plenum. They are on opposing sides, and the tubes are hollow - they go directly through the plenum. I recall that MY tubes are "loose" - by loose, I mean I can turn them, the ends are not connected to body of the plenum. They don't fall out, but they certainly are not "welded" to the plenum body.

I'm thinking the plenum needs to be taken out - OUCH - and repaired. ???? No / Yes?

Is there an easy way to get that puppy out without having to remove the manifolds? I guess I could cut the runner gaskets. Not sure how easy it would be however to put new ones on - once I yank that puppy.

Posted by: Philip W. Dec 23 2014, 01:45 PM

sounds like you probably found your leak, those should not be loose. Get ahold of Bruce Stone, he will have a nice newly powdercoated one most likely or have one done for you - in the mean time can you tape over those to seal them off just to test it?
Phil

Posted by: r_towle Dec 23 2014, 01:53 PM

put four large screw clamps on the rubber between the intake runners and the plenum, see if those are leaking.

As far as taking it off goes, well without the rubbers its about 1/2 inch or more away from the intake runner tubes, so if you can slide the rubbers back, you can do it...even if its just one side, then pull if off the other side.

Beware, you may need to buy new rubbers which I believe are NLA, so shop around for that first to make sure you get new ones the correct diameter before you shred them.

Rich

Posted by: lsintampa Dec 23 2014, 02:34 PM

I just ordered new rubbers from Pelican - seems they still have some. Not sure what I'm going to do next though. I'll have them if I need them.

I'm gonna try the hose clamp thing - but not until the holidays are over - it's getting nuts around the house - and I'm not about to go shopping - that's a given.

Will revisit this in a few days...

Thanks for all the input.

Happy Holidays - !!!!!

Posted by: r_towle Dec 23 2014, 02:36 PM

buy a can of carb cleaner....its safer than starting fluid....

rich

Posted by: The Cabinetmaker Dec 23 2014, 05:48 PM

2L intake runner sleeves are still available. 1.7 are not.

Posted by: ThePaintedMan Dec 23 2014, 08:51 PM

Len,

Try the new manifold-to-plenum seals like Rich said. If you still have a leak, let me know and I can weld the plenum for you. Or you can buy a purty one from Bruce - he's a great guy and his stuff is always pretty.

Posted by: lsintampa Dec 24 2014, 12:01 PM

Put 8 clamps on the fuel tubes - no difference.

George, I just sent you a PM.

Taking the plenum out isn't really on the top of my list, but I don't really know what else to do.

Tried to tape those support holes - and you really can't reach the bottom ones. So trying that is out.

Posted by: r_towle Dec 24 2014, 12:06 PM

if you can get your hands on a smoke machine, a halloween fog machine, you can blow smoke into the intake system to see if you can find a leak

If you figure 15 small leaks add up to one large leak, it may help

Posted by: lsintampa Dec 24 2014, 12:19 PM

Yeah, I think I understand what you're saying. The idle circuit is not even working if that middle finger (no pun intended) is making contact. (I think this is what you said). And if it IS touching something, you end up with a high idle - me thinks.

With how my switch is set up it need to go nearly fully CCW to be "set". Seems odd to me as well, but it is at the CCW limits in order to get that middle finger off any tracers.

Posted by: r_towle Dec 24 2014, 12:26 PM

I dont remember the schematic
Look at Panders site and see exactly what the readings need to be, on what pin at the ECU end of the wiring loom and see if its correct when the TPS is at idle.

Posted by: porsche913b_sp Dec 25 2014, 07:49 PM

Subscribed

Posted by: lsintampa Dec 26 2014, 09:40 AM

One reason for my confusion is that this diagram of the ECU circuit part that shows the TS clearly states that pin 17 should be in the "closed" position during idle. See upper left corner of the diag.

Pin 17 is the Middle finger you're showing as "touching nothing" at idle. (My translation is open).

I'm neither a mechanic or circuit master, but just looking at how the fingers (especially the middle one) travels on moving the throttle, says that at ANY position - other than "at idle" puts that middle finger in contact with the trace. SO, my common sense tells me that pin 17 should be OPEN at idle. Which is in agreement with what you are saying - and in opposition to the drawing.

Am I missing something?

Posted by: r_towle Dec 26 2014, 09:48 AM

Post a pic of your tps, but your logic is correct.
Idle is one position on the switch, open or closed.

It's a conditional switch.
At idle it's condition A
Rest of time it's condition B

You need to make sure condition A works.
That is how the tps needs to be set, so idle works.
The rest follows that baseline position properly.

Easy test, get it warm, get the idle fluxuating, unplug the tps.

I am still leaning toward distributor advance plates are dirty....I believe you mentioned they have never been cleaned, and yet you have not done that yet.
Small vacuum leaks also add to the mix.
Rich

Posted by: lsintampa Dec 26 2014, 10:44 AM

This is the current setting - not tested.

Posted by: lsintampa Dec 26 2014, 12:24 PM

Well pulled of the dizzy...

After removing the vacuum - the top plate doesn't bind or get stuck in any position.

I'm going to go over the other threads about the dizzy plates and just make sure that I'm OK on the dizzy side of the ocean.

That said, I could use a new o-ring anyway. So there's that.

Posted by: r_towle Dec 26 2014, 12:37 PM

Pull the plates out, check the ground strap, clean clean clean, new grease on the ball.

Watch out for the ball flying across the room....not a cool thing.

Posted by: r_towle Dec 26 2014, 12:39 PM

Hard to tell from that picture, but you should be able to see the contacts and where they are touching or not.
Might need to reset it.

Rich

Posted by: rhodyguy Dec 26 2014, 12:41 PM

If both of the tubes in the plenum spin, that means you have 4 potential leak spots. I fear you're spinning your wheels until you address them. Bite the bullet?

Posted by: r_towle Dec 26 2014, 12:47 PM

Looked at the simple test on pelican and it confirms that when you set it at idle correctly, you have no connectivity on that circuit, which is the idle circuit.

It also says to turn it CCW one hash mark on the mount, now I am not sure what he means by that, nor what it would do....but that is about as much variable as any switch has, many have less.

See what happens when you move it clockwise till you see ohms on that circuit, what finger is the out most contact touching, then go CCW until the ohm meter stops, then go a bit further.

There is a correct place for the outer finder to reside, as well as the middle finger.
Sometimes bending the fingers makes them shorter or longer to meet the needs.

Rich

Posted by: lsintampa Dec 26 2014, 12:48 PM

Yup, I agree... It's at that point... I'm just doing the prelim stuff - checking it out as I go.

I know the AAR is fine. Been there done that.

TPS - is still an open subject.

Dizzy is gonna get a bath.

Anyone know if the plenum can be taken out (and replaced) without taking off the intake tubes? I can easily cut the rubber hose connecting the plenum to the tubes, but putting them back on would seem difficult.

Onward ho!!!

Posted by: r_towle Dec 26 2014, 12:53 PM

It's not very hard to remove a few bolts on the head and pull off one intake runner tube....it's ten minutes work.
It's a whole hell of a lot easier getting to the one bolt underneath the plenum that holds it in place also.....
Pick that side.

If it was me, I would pull them both off and remount them clean so I know it's not leaking at the head mount.

Posted by: r_towle Dec 26 2014, 12:53 PM

Me...

Head---RTV---spacer---rtv----intake manifold

Posted by: lsintampa Dec 26 2014, 01:37 PM

Well, I'm tempted to put the dizzy back in and give it a try.

Before I cleaned the plates - I tried to move them by sucking on the vacuum and they did not budge.

Now that they are cleaned and back on - I can easily move them by sucking on the vacuum.

HMMM???

Posted by: r_towle Dec 26 2014, 02:13 PM

they should move freely in order to snap back to zero at idle...it can happen too fast for the plates to get there and it causes all sorts of wierd things to happen.

rich

Posted by: ThePaintedMan Dec 26 2014, 03:11 PM

These guys know their stuff Len. Try those fixes first, then we can tackle the plenum if need be.

Posted by: lsintampa Dec 26 2014, 04:59 PM

Well, plenum is out.

I'm too tired and sore to do any more tonight. It's time to start drinking!

Initial inspection of the plenum - it looks fine. What I thought were loose support rods must have been on something else. It was a long time ago - so I may have the parts confused.

In any event, the support tubes do not wiggle.

Interesting, I removed the left side manifold to get to what I needed so the plenum would come out. The middle nut - wasn't a nut on a stud at all. It was a bolt. I don't know how deep the stud hole goes - maybe the bolt was bottoming out and it wasn't sealing well? IDK.

Anyway, tomorrow I'll check the other manifold - see if it has something similar.

Manifold gaskets, injector gaskets - still like new.

BTW - how do I test the plenum (now that it is out) for leaks? Was thinking of putting some light inside and plugging all the holes - see if any light comes out in a dark room.

Is there a proper way????

Thanks,

Len

Posted by: r_towle Dec 26 2014, 05:51 PM

Tape up the holes, sink in water.

Posted by: lsintampa Dec 27 2014, 10:48 AM

Well that worked. What I learned - I'm not that good at taping up holes.

Lucky for me, I left the cold start injector and it's mounting plate on. That's where the leak was. The outer gasket (NLA) was hand made..... poorly I might add. Bubbled up like one of those fake treasure chests in a fish tank.

Anyway, I'm a bit peeved at a) myself for not finding it without going to such an extreme, and b) my motor builder that made the gasket. I never thought to second guess him.

As far as going to the extreme - well at least I can rest easily that my support tubes are in good order. Should I tape them now that I have the plenum out? Seems to me the tape on the bottom side would just melt?

One of the side intakes has a small ding on the lip - so it's a bit out of round. I'll crimp that out - and anyway, I'm putting clamps all around.

I have some honey-do things I need to get done around the house today. So not sure if I'll get some bench time or not.

I'm happy to have found a leak. Maybe I can get some good forward motion going on.

Not done yet, but I'm on the right path. Thanks Rich!!!!

Posted by: r_towle Dec 27 2014, 11:09 AM

If you go look for a leather punch set, Harbor freight has them, it helps in making gaskets....

Rich

Posted by: lsintampa Dec 27 2014, 11:26 AM

Was thinking red RTV high temp.

Thoughts about taping the support tube ends? They are solid and did not bubble, it just freaks me out - seems like a weak link in the plenum. IMHO

Posted by: r_towle Dec 27 2014, 01:34 PM

I would make a gasket, they should sell gasket kit/ material at the local hardware store, parts store, or hobby shop.

If you are worried about the plenum tubes, clean the paint off the area and seal them up with JBweld, or caulking or whatever makes you happy, then paint it up.

You won't sleep right till you do that, so get it done.

Posted by: lsintampa Dec 28 2014, 11:08 AM

Made a gasket, and used red high temp RTV on all contact sides for the cold start injector holder.

Plugged / covered the support tube ends with JB.

Waiting for the RTV to setup, then I'm putting the plenum back on. Sort of anxious to see what happens.

This is a picture of the gasket that was on the outside of the CS injector holder.

The water test showed the leak coming from the ends - DUH. The bolts go through and into the plenum. So air worked its way around the threads and out of the plenum (or into when mounted and the car at idle).

Posted by: lsintampa Dec 29 2014, 09:12 AM

This is getting to the point of being a bad dream.

That middle "bolt" in the manifold that I found in place of a "stud"... well it came out just fine. But when putting it back on.. guess what? The thing was stripped (inside obviously). No way to get it tight. Builder used some thread glue to hold in it - so taking it out - I had no clue it was stripped. Putting it back however, well that was a different story.

I'll deal with that at some point. I think the manifold is on tight enough not to leak. I got as much on that middle bolt as I can for now. I wanted to see what the results of fixing the cold start injector port leak would be.

The surge is less but still persists.

For grins - with the car at idle, I tried to adjust the TB switch manually. I noticed that turning it full CW or full CCW - the surging got really bad. So what I did was turn it full CCW the slowly turned it CW until the surging either stopped or should I say "got way better". Perhaps not the best way to go about it, but there did seem to be a "sweet spot" - anywhere else the surging was wild.

I don't have a fog machine, but I'm gonna get me a 10 cent cigar to make some smoke and see if I can see where the leak is at.

Maybe it's been the manifold all along?

UGH

Posted by: ThePaintedMan Dec 29 2014, 09:27 AM

You can still test for leaks at the manifold first. Start it up without changing anything else. Then proceed with the carb cleaner/propane leak test around the manifold gasket.

If it's leaking, you might have to do a helicoil for that stud... or *might* be able to get a few threads tapped with a metric tap. But it's worth testing for leaks first.

Posted by: Philip W. Dec 29 2014, 09:37 AM

surging always seems to be one of 2 things - lean running, or vac leaks. typically MSP and CHT failure are at the top of list , and a bad TPS but car should still run even without the tps hooked up , on mine i just found out that a back temp sensor- the one that screws into the top of the plenum right next to the TPS on the back side, can cause these symptons as well. Mine had gone bad and was causing some a lean situation aand resultant bad ilde, surging, and bad issues. i was sure i had an electrical problem the way it would cut out and go up and down. but after replacing the temp sensor, perfect idle. - once you have your manifolds and plenum taken care of, test that temp sensor.

Posted by: lsintampa Dec 30 2014, 08:52 AM

At this point - it seems I may be near normal.

I reset the dwell and timing. I'm not sure why timing should be set with the car at or near 3,000 RPM? It's been my experience over the years to set timing at idle.

Thinking about that, it would be next to impossible to do, when at idle, the surging was nuts.

Anyway, with the help from my wife to jack the rpm's up to around 2500 - 3000, I set the timing. Ended up retarding the advance quite a bit from where it was.

That seemed to drop my idle way down to under 900 RPM - and the surging seems to be near gone.

I don't want to say it's resolved - it would be nice to know for sure if the timing may have been another part of the issue. (along with the leaking cold start valve).

I can FORCE the surging by doing one of two things.

1) advancing the distributor a lot

2) at idle muck with the throttle plate switch - take it off it's idle setting

Anyway, there have been times with I "thought" it was right - just to let it sit for a while and watch it go nuts on me.

Will test again later today. Keeping fingers crossed - that maybe it's settled down?

Posted by: lsintampa Dec 30 2014, 03:23 PM

I'm at my wits end.

Every time I think it is back to normal - I'm wrong.

At this point I really don't think I have a air leak. Maybe there is still an issue, but I can't find it.

When cold, the car does just fine, then as the AAR valve begins to close and the idle goes lower - as it should - that's when all the surging starts.

In fact - and for what it's worth - when I first start it and PLUG the AAR valve, it still idles fine (no surging) - so it seems to me the surging is only AFTER the car is hot.

IDK, I'm really close to just living with it. Aside from idle - car runs great.

BTW - the adjustment knob on the ECU - I've yet to notice it making any difference, at total CW or total CCW - the car (idling) just behaves the same.

If anything earth moving happens - I'll follow up. At this point I'm just gonna

Posted by: ThePaintedMan Dec 30 2014, 03:37 PM

You're still just walking around in the dark until you can isolate entire component systems. You haven't told us whether you've tested for leaks yet or not...

The computer is working against you at this point because somethin ain't right and it's trying to make it right. Once we know for certain there are no leaks, then you can begin to narrow things down. The next step at that point is probably the CHT sender, as others have mentioned. Think about the symptoms - it runs fine till it warms up, right? You need to follow that logic through.

You're a smart dude Len, don't get frustrated. Isolate systems first, and then rule them out. Changing parts and turning dials is not a great way to troubleshoot IMHO.

Posted by: r_towle Dec 30 2014, 04:23 PM

Timing is set at 3500 rpms to guarantee you are setting the timing with full advance on which at that speed is purely based upon centrifugal force and not vacuum.

Its a unique way of timing, and if you use a zip tie you can easily pull the throttle to the right speed and set the timing accurately.

Now, when you change the timing by ear, or by hand, you WILL screw things up.
So, STOP doing it. its not right and it will certainly create an issue.

Go back, set the timing by the book.
I know you changed it again, so go back and reset it properly.
Then, and only then will things sort out.

1) set Dwell
2) set timing at 3200 rpms steady, not blipped (watch for variation in timing when the rpms are steady, that will define a new issue....if it wont hold steady)
3) turn the ECU knob to full rich
4) set the TPS to the only correct spot it can be set....(again, its not a tuning aid and its not adjustable...stop messing with it)

If you do all of these things, you are now setup properly.

See if that works.
If it is close and idle moves a little bit let me know.
If the timing mark moves while you are watching it with the light at 3200 rpms, let me know.

You need to stop messing with three things at once.
Set them all properly so this can be diagnosed and fixed.

Proper diagnosis involves changing one single parameter at a time, not two or three.

you stated
I can FORCE the surging by doing one of two things.

1) advancing the distributor a lot

2) at idle muck with the throttle plate switch - take it off it's idle setting

Number one, yup, so set it right
number 2, yup, so set it right.

Rich

Posted by: lsintampa Dec 30 2014, 04:33 PM

I just ordered a new TPS switch. But I can and will follow your guidelines to the letter and report back using the one I have. I believe it to be set correctly at this point.

Thanks,

Len

Posted by: rhodyguy Dec 30 2014, 09:53 PM

nice write up rich. concise and to the point.

Posted by: lsintampa Dec 31 2014, 02:13 PM

So, I set the timing... had wife hold RPM (using the dash tach) at 3200. I did not notice the timing mark moving. Seemed to hold steady on mark.

Clamped down DIZZY, shut car off.

Turned ECU knob all the way clockwise (rich I think)?

Started the car.

No surging, but the idle is now LOW - like maybe 400 RPM. The generator light comes on. She does stall out sometimes. At times it will catch itself and stay running. If I get on the throttle and let go, that will usually result in stalling.

Turing (opening) JUST the air bypass does little for the idle. It makes a LOT of noise (sucking wind), but has no to very little effect. I turned it back to almost closed, which is where it was to start.

So that's where I'm at. No surge, low idle. ECU fully turned clockwise.

Thanks,

Len

Posted by: The Cabinetmaker Dec 31 2014, 03:56 PM

Why full rich? Turn it back half way. Did you have the vacuum hoses disconnected and plugged when you timed it?







Edit: just saw that Rich had you do that ? Why full rich, Rich?

Posted by: lsintampa Dec 31 2014, 04:11 PM

Well, I'm just following Rich's routine to the letter, as I said I would. His bullet point number 3.

Yes I had the vacuum hoses disconnected and plugged... at the throttle body.

I saw no need to plug the vacuum on the dizzy.

I'm cool until Rich has had time to chime back in. I'm sure there's a method to what he's asked me to do.

At this point, I'm surely not in any rush. And it's becoming more obvious that I'm clueless!

Posted by: Philip W. Dec 31 2014, 05:14 PM

Running rich will cause a slower idle. Slowly one click at a time turn back and you shod see the idle change while making it more lean.

Posted by: lsintampa Jan 1 2015, 02:22 PM

Recap 75 2.0 d-jet - was a California car, cat deleted by some PO, new (used) FI harness for a non California car.

Latest update...

Following Rich's guidelines....

Day 1:

1) Set idle - motor warm, RPM's at 3200, pulled vac lines off dizzy, plugged the holes to the throttle body. Timing mark did NOT move - held steady.

2) Turned ECU knob full clockwise - to full rich position.

3) Adjusted TPS - per the Pelican site.

Car now idles very low - most times it will eventually stall out.

Day 2:

Today the motor was cold. I didn't know what to expect, but leaving everything as was, I just went for it.

Car started. It took a few tries - maybe three. But it had a hard time staying running. The AAR valve was full open because I could here it sucking air. The extra air had NO effect on the idle at all.

After a while the car will run, but the idle is just above stall point - and it catches itself most times, but eventually will stall out.

I have a new TPS coming in. Most likely it will get here sometime next week.

For what it's worth, I've never seen the ECU knob have any effect on the idle - ever. I laugh every time someone tells me to adjust it, because I know it's not going to do anything. Maybe it is broken, or the idle circuit is fried, or the TPS is shot. I think when the day comes that the knob actually has an effect on the idle, I'm gonna fall over.

And yes I did try to turn ONLY the ECU knob (day 2). I'd turn the motor off, move the knob like 1/4 turn - restart. I went from full rich to full lean - no setting had any effect.

I've put the knob back now to full CW (rich) position - as it was this morning.

Posted by: r_towle Jan 1 2015, 04:45 PM

Once you have it warm and running, set the idle using the air bypass screw in the throttle body.
Sounds like you are almost there, but you may have closed that idle air screw long ago to get it to stop fluxuating.

Rich

Posted by: lsintampa Jan 1 2015, 07:45 PM

That does nothing. Even when the AAR is wide open (when the motor is cold) the idle is low low low.....

Adding more air - regardless of how I do it has no effect on idle.

Posted by: Java2570 Jan 1 2015, 09:29 PM

Air bleed screw in throttle body not having any effect on idle is typically caused by a very lean condition. I would definitely check fuel pressure and see what you are getting....an air/fuel ratio gauge would be a good investment also.

Posted by: lsintampa Jan 2 2015, 12:40 PM

Fuel pressure is steady at 28 PSI

Posted by: lsintampa Jan 2 2015, 03:27 PM

Double triple checked and reset:

• Fuel Pressure 28psi
• Dwell @ 50 Degrees
• Timing correct
• TPS - set per Pelican's site

Idle is about 600 when warm (when read with multi meter on coil). I don't know about when cold - will be able to tell tomorrow.

Knob on ECU - no noticeable effect.

Air valve - little to no effect.

Worth noting I have a new TPS board on the way. I'm keeping my hope up that may have some positive results.

???

Posted by: ThePaintedMan Jan 3 2015, 07:22 AM

What did you figure out with the missing manifold stud?

Posted by: lsintampa Jan 3 2015, 08:19 AM

George,

A while back when I took the manifold off I noticed that the stud had been replaced with a bolt.

I didn't notice that it was stripped, until I put the manifold back on.

It's back together as it was. The bolt is still stripped. It's in as tight as it can be at this point. Again as it was. I've not revisited that issue, but using your propane test there are no leaks around that area.

I may tap it out this weekend.

Posted by: r_towle Jan 3 2015, 10:29 AM

If that is an intake stud, it's going to make tuning the car very hard to do.
It's leaking air.

Posted by: lsintampa Jan 12 2015, 05:43 PM

I'm dealing with the intake stud this week - hopefully. Haven't done much else - except put a new TPS board on.

But I agree it makes no sense to plod on when I know there are other issues to deal with first.

Just for grins, I did pull up a picture of the motor AFTER the rebuild and in this shot if you zoom in on the intake, you can clearly see there is a BOLT in the middle where it there should be a nut on a stud.

That's the oddity that I discovered when I pulled that intake off. I was expecting a nut and came out with a bolt. Putting it back on that puppy was for sure stripped and needs to be resolved.

There will be an ending to this saga. Sadly for now, it lingers on.

Posted by: The Cabinetmaker Jan 12 2015, 06:18 PM

Is that the regulator on the black bracket at the rear tin?

Posted by: lsintampa Jan 12 2015, 06:54 PM

Yup, and yes I know the mount point is just below it. I may move it at some point, but that's how it was installed.

Posted by: r_towle Jan 12 2015, 10:11 PM

Did you tap that bolt hole for a larger stepped stud?

Posted by: lsintampa Jan 12 2015, 10:40 PM

Haven't yet... game plan is to tap it out to 9mm - use a VW exhaust stub (9mm / 8mm). Think it will need to be cut to length as I believe the exhaust stubs are long.

Maybe middle or later in the week. I have a friend that works on the older VW's and we're trying to get together this week.

Once that's done, we'll seek out leaks and deal with what we find after the stud situation is put to bed.

Posted by: lsintampa Jan 16 2015, 03:16 PM

OK, finally got that stud fixed today.

So, put the manifold back on hooked everything up, reset the timing again. Issue persists.

Sprayed carb cleaner all over every nook and cranny - nothing seemed to be sucking it in. Sprayed the intakes at the manifold, at the plenum connections, cold start valve, every hose, and the throttle body.

No leaks to be found.

New TPS board - adjusted per Pelican's doc.

Idle is way low, to the point it will stall out. Adjusting either the ECU knob or the air bypass has no effect.

If I pull the hose off the MPS - the car idles better. As soon as I put it back on - no dice.

The TB has two hoses that go to the vac on the dizzy. Not sure which is which, but one is high up on the TB and the other is smaller and lower on the TB. If I pull the larger hose off the TB (on top of the TB) the idle goes way up.

I haven't adjusted anything. Timing / dwell / leaks / valve adjustment are good.

NOW that said. Reminder that this was a CA car and had CAT at some point and speed limiter. Both removed by some PO and I have a replacement FI harness from a 2.0 NON-CA car hooked up. I don't see where that should be an issue, just mentioning it again. I don't know if the ECU is different for one or the other - or if it matters.

Finally, I know that at one point there was a short in the FI harness. It was up around the TPS area. I know this because the wires on the old harness were fried. I wonder if that short may have cause a board issue in the ECU.

Lastly, I'd love to beg, borrow, steal, (maybe even buy) known good ECU and MPS, to try. I really don't know what else to do.

I'm no expert, but since I've started on this issue, I've learned it really is a simple setup. Ain't much going on here.

Posted by: r_towle Jan 16 2015, 03:23 PM

if you remove both the advance and retard vacuum lines from the distributor, and put a bolt in each one so there is no leak at the intake, does the problem resolve?

Starting to suspect your distributor here.

rich

Posted by: lsintampa Jan 17 2015, 12:06 PM

Negative. Actually it made it worse - that is if it would start and run at all.

With them off, if it does manage to start and stay it surges and will die out.

With the hoses on - it starts, idle is maybe 300, or less - and eventually dies out. The idle is so low, it's hard to determine if it is surging at all.

Started to wonder if the timing mark is correct? After the motor rebuild it came back with a bright yellow paint line on what I'm assuming is the correct timing mark.

Well I double checked the timing marks, and TDC is painted white, and the big yellow blade is @ 27 degrees... so timing appears to be set correctly.

I just wanted to double check that TDC was not yellow. The white on the TDC mark was on the back side of the fan, so you can't see it without a mirror.

Posted by: lsintampa Jan 27 2015, 05:07 PM

Don't know if anyone is still following this or not....

Anyway, thanks to Carr914 I was able to borrow a MPS and ECU that he has as a spare to go with one of his cars that he's selling.

ECU looked old - mine has a nice shiny sticker on it (it may have been rebuilt).

I did notice however when I sucked on the loaner MPS, there was a distinct thunk and you could feel stuff moving about inside.

When I suck on mine, nothing feels like it is moving inside - so I was somewhat optimistic.... with caution.

So with just those two parts, I fired up my car - with my stuff to let it warm up and start acting funky. Didn't take too long.

After swapping out every combination of parts, the bottom line is that the MPS from the loaner is much more at home with my ECU.

I can get it to run at idle - with no surging. If I shut the car off and put my MPS back in, it starts - but dies - won't stay running.

Shut it off, put the loaner in and it starts and keeps running.

Shut if off, hook up my MPS, surge - sputter - die.

Will do more testing tomorrow morning when it's cold.

Maybe on the road to recovery..... we can hope.

Posted by: porsche913b_sp Jan 27 2015, 05:11 PM

Was your original MPS able to hold a vacuum test ?

Posted by: lsintampa Jan 27 2015, 06:03 PM

I don't have anything to test that. So I can't say. It does offer up a lot of resistance when I just use my lungs. Not conclusive, but that's the case.

When I'd do the suck test on the loaner, there is a for sure sound that something inside is moving. Not so with my MPS.

That's all I got for ya.

Posted by: r_towle Jan 27 2015, 06:08 PM

Suck on it, if you can make your tongue stick to the end, it's holding a vacuum.

Posted by: lsintampa Jan 27 2015, 07:57 PM

Well if I "suck on it", it will stick to my tongue. However, nothing inside moves, unlike the loaner MPS.

So my question to you is why is there such a difference between the inside movement between the two units???

Posted by: lsintampa Feb 22 2015, 10:12 AM

Well - we're done.

Issue resolved.

Problems fixed:

1) rebuilt MPS - thanks to Jeff Bowlsby
2) found and fixed a stuck de-accel valve
3) cleaned up and lubed the dizzy plates
4) replaced TPS board - thanks to davesprinkle

Adjusting the TPS was the most difficult to do.

By chance I met someone at our last PCA social that is retired, but he worked for Bosch as a trainer on d-jet (of all things). I got some documentation on the d-jet system from him. Most of it was for VW, but parts pertained to the 914. One thing I found in that documentation was that if your surging is "wild" up and down, they suggest you adjust your tps - as r_towle said, there is only one position it can be in for idle.

I tried the Pelican method - and it seems to be good. Then just for grins, I started the car an mal-adjusted the TPS - and it started surging like mad.

Anyway, I'm in a good place now.

Posted by: 914_teener Feb 22 2015, 12:53 PM

Nice.

You motor is stock cam 2.0 with d-jet?

Posted by: lsintampa Feb 22 2015, 02:27 PM

correct!