I recently replaced all of the vacuum/ fuel/ miscl hoses in my '76 2.0 with new Genuine German hoses including the stuff at the fuel tank. Intake runner to Intake manifold "hoses" were also replaced so ALL the engine's rubber is new and tight. I carefully followed the guide on Pelican so I'm pretty certain everything is plumbed correctly. I adjusted the valves before I resinstalled the engine, and have about 1/2 and hour of running time on it subsequently. After careful adjusting my timing (was at 20 degrees BTDC @ 3500RPM, now is 27) I started down Brad Anders' list.

Idle DOES respond to adjustment on the throttle body, but DOES not respond to ECU IDLE mixture adjustments.

Throttle lags on acceleration.

Car is running "stinky" rich... wisps of black smoke when throttle is goosed.

Cold Start valve has been disabled by disconnecting supply line.

I suppose I could always go back and check my work and readjust the valves to make sure they aren't too tight as I habitually tend to adjust on that side of the "tolerance".

Anyhow, in order of priority, I'm guessing the following is the best bang for buck in trying to pin down the "running rich" issue, tell me if you agree:

1) Readjust valves
2) Check fuel pressure
3) Remove Head Temp sensor and check resistance in ice bath, then room temp, then boiling water.
4) Ring out harness to make sure head temp sensor is being "listened to" by ECU..
5) Suggestions???

The temp sensor on the plenum is plugged in, and the MPS is connected properly (and holds a vacuum)? You've probably covered those, but just checkin' the first ideas I had.

I'm guessing that these should be checked after adjusting valves in terms of likely "suspects"?

Thanks

I would check these first just because it will only take a couple minutes and they can definitely cause your symptoms.

Understood.

Thanks for advice

check the CHT (at the head), once cold and once warm. I had one that was fine until the engine was at temp - then shorted out. It was bad enough to leave me on the road stranded. Luckily my buddies saved my bacon and towed me home.

Good luck Brian. Keep us posted.

How did it run before replacing all the hoses? If the "rich" symptom only showed up after the hose replacements, then double-checking the hose routing/connections might be the first priority.

CHT? Cylinder Head Temperature Sensor?

Ayup, also known as TS2 (temp sensor #2)

It's been a few years, but I test drove the engine in Mike Mueller's car and don't remember and throttle lag or smoke. Like every assumption.. I'll go through all my hose routing from scratch... can't hurt.

Thanks for advice.

Also!

You wrote "I recently replaced all of the vacuum/ fuel/ miscl hoses in my '76 2.0 with new Genuine German hoses including the stuff at the fuel tank. "

Make sure you don't have a kinked return line to your tank, that will make your fuel pressure go through the roof.

and check the CHT and MPS holding a vacuum of 15hg for 5 minutes

oooohhh.... that sounds nasty.... and here I thought I was thinking ahead by making sure there was plenty of slack in the new high pressure hoses at the tank so I could easily pull the tank without needing to disconnect... hope it didn't backfire on me...

There's a bunch of stuff on my web site about rich running. The top reasons for rich running that spring to mind are:

1. Leaky, wrong, or maladjusted MPS
2. Open head temp sensor (either bad sensor or broken wire in sensor or harness)
3. High fuel pressure (malajusted or blocked return line)
4. Leaky cold start valve (spewing gas into the plenum)
5. Wrong parts (wrong ECU, MPS, CHT, injectors, etc.)

Hey Brad,

Its good to see ya posting here. Hope you're doing good and you're healthly too.

Geoff, thanks, I post here from time to time, it seems like 914Club has a lot more traffic these days than PP's board.

Health is fine. My 914's getting a long-overdue rebuild right now, should be done in a month or so. Very stock rebuild, I'm going for reliability and smoothness. Can't wait to have a motor that has some compression and manifold vacuum again - I think my ring gap was about 1/4"!!

Here are a couple of pics of my engine rebuild that's underway:

http://members.rennlist.com/pbanders/more_..._Engine_Rebuild

Yeah, I know, looks like every other T4 that ever got built up. But that's the way I like it.

looks good!

Stock cam, haha sick of the Web73?

I went with Rabies version of the Web73 in my recent refresh of mine. Yup, it was a chore to tune the Djet but it runs sweet now.

When we ripped it apart, turns out the cam was stock, not a Webcam 73. Tuning the FI should be easy. I have a brand-new 043 MPS that I used to setup another good MPS I have to identical injection durations across the full vac range. We're going to start with that one and see if any tweeking is needed. I'm trying to hold on to the new MPS for as long as I can - considering that they're $1000+ these days!

Did you observe the cooler running that Jake says comes with that cam? I think he was saying it was 30 deg. F cooler than the stock cam. I never did get him to tell us what was specifically different (lift, duration, ovelap, etc.) with his cam over the 73 or the stock.

On mine its about 20F cooler (oil temps)but I also upped the compression to 9to1. On 90F days it would hit 260F sometimes running hard at AXing. Now 240F is the warmest its been running hard on 95F days so its an improvement. Driving around town/freeway its about 210F.

The difference is 2 degrees more of exhaust duration I think which is to cool off heads more as I have observed on both my 914 and Westy. The Westy runs 250-300F head temps now which is waay down from stock before.

Yes, I have a NOS 043 and a Clean OEM 037 that I use to calibrate the Wavetek before setting any MPS I work on.

Boy the MPS I use now is in the .80, 1.35, 1.76 range for this motor to get a AFR of 13.6 to1 at PL and 12.5 to 1 at WOT. idles ok too.
NO, leaning out at higher rpms -5000 to 6500 using a LM1 to track it. Should have Mythbusters prove the ole wife's tale false about Djet leaning out at 5000 and above.

It's been a few years, but I test drove the engine in Mike Mueller's car and don't remember and throttle lag or smoke. Like every assumption.. I'll go through all my hose routing from scratch... can't hurt.

Thanks for advice.
[/quote]


Brain,
I bet That engine came out of my first 914. I let MikeM use it and one day he sold it
I have all the smog junk at home. Yah he paid me

Mike

I tested the Head Temperature Sensor this evening in my '76 2.0. P/N is 0 280 130 012. My measurements were different than the ones posted by Brad Anders.

Brad's Measurements:

32 def F 61 deg F 210 def F
N/A 2.85K ohms 199.3 ohms


Mine:

32 def F 61 deg F 210 def F
549kohms 1.85K ohms 327 ohms


It seems to be behaving "rationally", i.e. no short, or open condition, but the rich mixture is present. I'm thinking the wiring harness is the next suspect unless somebody thinks these numbers are too far off.

What do you think?

Sounds like the TS2 is "close enough" (or better), so keep looking for the source of your rich running. How's the fuel pressure again?

--DD

Will rig up pressure measurement tomorrow and check it out.

I'm back..... Holy CR%P!!!!

I rigged up a 60 PSI gauge to check fuel pressure as the next item in the "checklist"...

I fired her up and went over and looked at the gauge... it wasn't making sense....
somehow, the needle had gotten itself on the wrong side of the "Zero" post...

I killed the engine and had one horrible thought.... I backed off the hose clamp sealing the gauge to the fuel pressure line.. and sure enough.. the needle started moving away from the "Zero" post.... the damn thing had gone all the way around the clock, and past 60PSI


yes, I've been by either my installation of fuel lines backwards.. (most likely).. or a pinched return hose in the tank area....

Silly Silly me....

Kind of explains why my cold start valve was "leaking" and the car was so freeking stinky....

Now to sort out the plumbing problem..

More later... (wish I had a camera to show that needle pegged, it was almost funny!!)

Right on! progress..

Okay... quicky.... as the fuel lines come out of the "hell hole", they are arranged so one is forward of the other. Which is the high pressure side and which is the return? (Assuming I didn't switch them at the tank and left them in the "stock" connections")

I can't recall which is which. With your 76 your hoses are the same size (7), rather than the early cars with 7/9 hoses. What you can do is remove your splash pan up front (under the steering rack) and reach in the access hold and feel which lines are which coming out of the tank to the tunnel.

Plus, my bet is on a kink in the return line - and that is where the kink would be (right under the tank).

Check the diagrams on our site. Supposedly the front one is the supply, the rear one return.

Then again, you could just look at which one your pump connects to up front, then see which line that is at the rear.

Or you could just swap them and see what happens to the pressure.... I don't think it'll get that much over 60 PSI, so you won't be any worse off.

--DD

Hi Dave,

I swapped them and pressure dropped to almost nothing... engine ran anyhow, just not happy.


Travis

This points to fuel pressure regulator not regulating... or a big kink in the return line.. guess I'm pulling the tank tomorrow (out of daylight).

I did build a lot of slack into the supply and return side at the tank...

CHANGE YOUR OIL

your oil probably has gas in it from having the injectors fight against 80+ PSI of fuel--they'll leak quite a bit at that rate.

That stands to reason... before I disconnected the cold start valve, fuel had accumulated to almost 1/8" in depth in side the intake manifold.

Lots to do tomorrow....

#3 on my list of reasons for a rich mixture.

If you've been running it this way, as others have said, your oil is full of gas. You also need to check that your CSV is still functioning properly, and verify that your injectors aren't now leaking.

I had exactly the same problem (due to a clogged return port on my tank) when I converted from carbs to stock FI in 1985.

Hey, me too! Clogged return line when I switched back to FI from carbs in 1996.

Engine hasn't had more than 1/2 hour running time since put back in car. Will check oil this evening. Originally, my cold start valve was leaking like mad since the intake plenum was full of gas. I disconnected it and plugged the feed line.

As far as injectors leaking, do you feel that this huge overpressure can damage them? I will pull them tonight and fire up the pump, once I've rooted out (hopefully) the "kinked" return line, and then verified that I'm regulated back down to 30~PSI.

BTW, any benefit to running a little on the high side, say 35PSI? (while I'm in there tweaking it...)


Continuing to be the Poster Boy for Pauls Fuel Injection Troubleshooting site....

thanks

NO

DJET likes low fuel pressure.

One could even use the 50PSI line, since djet likes ~32PSI of fuel pressure or so.

That's 29 PSI, not 32.

Adding fuel pressure will make it run richer across the board. Not sure if it's a linear addition, or what, but it will run richer. (At least, until the injectors stop atomizing the fuel correctly.) If that's what you want....

Too much fuel pressure can, sometimes, make the injectors leak even after the pressure is normal. I'd check 'em when you get the fuel pressure back to normal again. Just take 'em out of the intake and see if they leak when you have the fuel pump running. Be ready for the mess if they do leak, though. A face shield and a fire extinguisher might be good ideas...

--DD

hence the ~ Dave

While digging below the fuel tank, I found a line which MAY have been pinched between rear of tank and bulkhead. I was able to wrestle it out without moving the tank.

After firing up engine, fuel pressure was back to being pegged (again, way past the gauge's max reading).

I shut down, and got my wrenches to try adjusting the fuel pressure regulator. I went back to run the fuel pump, turned the key and got NOTHING>>>>

No lights, no starter nothing.....

moments before, everything was fine electrically.

I took the fuel pump out of it's hole and it lying in the front trunk, wires tight, all connected.

I've never had ANY electrical problems before. Do the ignition switches just instantaneously go bad? No smoke "leaking" out of wires anywhere...

Solving one problem causes another.. gotta love this stuff...

Finally... I believe I have found my problems...
1) Electrical... red heavy wires are routed to battery post. I had replaced the battery termination post with a new one when the battery was new, but not with an OEM one. I had drilled and tapped the lead and used a 3mm stainless bolt.. bad idea relying on tapped holes in lead.. it simply worked itself loose JUST by Chance..

2) Crazy fuel pressure.... I have the regulator not only plumbed AFTER the injectors, but with the inlet and outlet (regulated side) flipped...

I'll tell you one thing, Bosch sure built a hell of a fuel pump...after 30 years, its still pushing over 60 PSI!!!

....man having kids sure sucks the brains and common sense out of you..( I used to be a troubleshooting genius..) ............. I haven't changed the lines yet cause guess what... mom wants us all to take a break and go for a walk "as a family"...

Can't argue with that.. tune in next week when I show more evidence of senility and drive into a wall....

The pressure regulator does indeed go "downstream" of the injectors, Brian. Not with the lines backwards, of course...

--DD

Its at the end of the high pressure side of the fuel rails. The inlet side is the 90' and the straight out fitting is the low pressure side of the regulator.

Hi Dave,

I used you diagram to replace the hoses with all the right OEM stuff.. but I never looked CLOSELY at it.. and now maybe it will help the diagnostics

Click to view attachment

Went back and looked again... only problem is regulator is in backwards...

Click to view attachment

Will try again..

thats a small problem....fixable too.

Well.. I discovered why I had the pressure regulator plumbed backwards:

Click to view attachment

I had downloaded this and printed it out at least 7 years ago. Seems it has gone through a small revision

I hate it when I immediately accept the assumption that I'm going senile and that it MUST be my screw up!



Well, you know what they say about "free advice"

Mr Darling, I believe this is your drawing? I appreciate your efforts none the less

Yup, that's an earlier version that had the FPR "drawn" backwards. It was my first major revision of the diagram, and I goofed. I recall that I fixed it relatively quickly ("relatively" being the operative word), but you seem to have gotten one from when it was backwards.

Oops!

--DD

New regulator put in last night.... stunning how fast this project is progressing isn't it??

Pressure dropped immediately to a reasonable 30psi and no more "hot no start".. wow. At this rate, I'll be 50 before I'm back on the road again.

Dang Brian, you should have waited another couple weeks and rounded it off to an even year!

Hey, progress, is progress.