I'm having the worst time with my 914 this year. Since I've pulled it from the garage this Spring it has run terribly. I've been replacing and fixing and updating the D-Jet parts for some time now. Last year it ran super toward the end of the drivable season, but after sitting for seven months now suddenly it isn't.

Here's what I've done:

The CHT sensor is brand new and correctly installed.
The cold start injector appears to work correctly.
The TPS has a new circuit board and is adjusted (double checked just now) according to the Pelican article.
The AAR works perfectly after a rebuild and closes correctly after ten minutes.
The MPS has been rebuilt (by me) and the behavior is identical to a known good MPS. Using the table at the pbanders website, the car won't idle at all because it runs so lean it pegs the needle on the AFR gauge.
The vacuum lines are all new. A smoke test confirms NO VACUUM leaks, which I would have thought to be the obvious culprit.
The throttle valve has been rebuilt (by me).
The timing is dead on a 27 degrees at 3500rpm.
The fuel lines are all new (stainless + new lines).
The fuel pressure is set to 29psi - but strangely the inline gauge I have shows a rather jittery needle which it didn't used to do.
The car has a mostly 1973 1.7 liter engine.
I've tried two different ECU modules - one from 1971 without the adjustable idle mixture knob which is the one I've been using and a known-to-be-good ECU from a 1973 (037) with the knob, which made no difference where it was set.

My main issues at this moment are (a) very erratic readings from the AFR gauge and (b) high idle. The idle will eventually sit at about 1200rpm once hot, but it will fall no lower. If I tighten the air bleed screw all the way in it continues to idle at 1200rpm. But I unscrew the air bleed valve the idle does increase a tad.

If I adjust the MPS inner screw to achieve a richer burn (say to 13-14:1), the car starts right up and idles, albeit 300rpm too high. If I drive it at cruise it runs super rich at 11 or 12:1. Partial throttle is okay at 14-15.5:1 but then it suddenly just pegs lean, chokes, sputters, and then recovers. This seems to happen at random. If I hit full throttle it begins to rev up but then chokes on a lean condition, but faster than just partial throttle.

I AM CONFUSED.

I think your smoke test failed. Sounds like another vacuum leak...

Try reusing your old CHT sensor first...Just for kicks

Then your fuel filter....

If I'm wrong, I eat a bug....

Well, if there's a vacuum leak it isn't coming from the main vacuum hoses. I shot numerous small spurts of carb cleaner without noticing any blips in the idle.

I've disconnected all of the lines from the plenum except for the MPS - but also without success. So tightened down the intake runners at the heads. Those gaskets are new, as are the injectors and seals. A few of the bolts were a tad loose but nothing consequential. The tube gaskets that connect the runners to the plenum are new and clamped with nice clamps.

But I did find some new things:

1. According to my fancy timing light, the tach on the dash is 250-300 rpm too high. Weird. I have no idea why that would be the case.

2. With the air cleaner off, I can plug the hose that connects to the air cleaner, and then to the small vacuum connector, which splits off and connects one hose to each head. When that I happens the idle drops to 770rpm. That is with the idle air bleed at full tightness. But if I open the air bleed screw the idle increases quite easily.

3. Strange: if I reconnect the air cleaner and plug the hose that connects the heads to the air cleaner, the idle sits at 1050. So merely by installing the air cleaner the idle jumps over 200rpm.

Still confused.

Well, I took it for a small spin around the block. The idle, even a touch high at 1000-1050, is probably acceptable. I'm still not sure why the air cleaner increases the idle.

But at the least the idle is stable. Now the major problem is just very lean partial throttle. As in 17:1. I have no idea how to change just the partial throttle mixture.

I have had:
1 intake plenum that had a crack in it.
1 intake plenum that had rust holes in the bottom.
1 throttle valve that would sit off center and bind while closing.

All of these caused high idle speed.

If the throttle valve is closed and the idle screw is bottomed out and the idle is still high, air is getting in somewhere else. It can't idle high without air from somewhere.

Not sure what causes lean mixture atpart throttle but I suspect it is related to MPS adjustment.

Good luck
Jim

The idle rises with the air cleaner installed 'cause it fattens up the mixture.

The Cap'n

For sure it must be extra air coming in. I can't even adjust the MPS rich enough to smooth it out, so it's extra air for sure. The TPS is completely perfect. I believe the plenum is good also simply because I pulled it a while back, blasted it, and painted it. Didn't notice any cracks but I suppose it's possible.

If it isn't any of the places I've checked I have no idea where else to look.

go swap your MPS and ECU with one from a buddy's car that runs well. and what is the hose that connects both heads to the air cleaner?

I've done that. I had a matched-pair, known good MPS and ECU. Same results. Only leaner.

Some engines had small 13mm ports right by the injectors - one on each side of the motor - where a vacuum line is connected. I forget exactly what they're called. It seems to me like a sort of PCV system, even though the car already has a PCV valve.

Are you saying that you are adjusting your mps? If so, I found very similar results at first. Do you have an inductance meter to work with. I cannot say enough about pbanders work, but it stops short of getting the car running. I ended up making three new mps units and adjusting them differently. I made graphs of vacuum vs inductance and those helped me see where I would be rich and where I would be lean, and together with the af readings made progress. I do not see how it would work without both the inductance curve on the bench coupled to the af readings in practice.

Sorry, pushed add twice

Yes - I'm making adjustments to the MPS. I used my Waketek LCR55 to set the values on the bench to exactly what the pbanders site shows. Using that as a starting point, I then set about making adjustments via my AFR gauge.

Head port (2) to anti-flashback valve. Hose from anti-flashback valve runs to air cleaner. Function = crankcase pressure relief and in case there is a backfire, the gasses in the head/crankcase are not supposed to ignite (anti-flashback valve).

And the plenums do suffer from cracks.

Try a new fuel filter.

May be partly clogged causing your pressure to flutter.

That would explain not being able to accelerate, you are not getting large amounts of fuel when needed.

Runs rich at idle because you fattened it up in the low fuel demand range.

Be a cheap box to check off.

John

I agree. You may also have a kinked fuel line underneath the tank. You indicated that fuel lines were replaced. Finally, are you sure the debris screen (sock) inside the gas tank is clean?

Sounds like your PCV valve may be open more than it should. Check through the article on Brad Anders' site about the PCV. I have also heard of people putting a restriction in the PCV hose that hooks up to the oil filler.

Borrow another fuel pressure gauge to double-check yours. I had a bad one that read too high, threw off everything when I was using it to set my pressure.

--DD

Everyone, thanks for the responses.

Today I spent the whole day retracing my steps and I found a few small problems. I re-adjusted the valves. They were good before but now are a touch quieter. I also got to thinking that maybe my timing was too advanced, despite having it spot on. So I took a step back to verify the TDC mark on the flywheel and found that the PO had helpfully put it in the wrong place. Only by one "fin", but I am looking for small problems. So I retarded the timing by two degrees. This seems to have tamed the idle issue.

I also checked the plugs (clean), air filter (clean), and ordered a new fuel filter just to check it off the list as fourblades and toadman suggest. Last year along with the fuel lines I also pulled the fuel tank, boiled it clean, powder-coated it, replaced the fuel sock, and coated the inside with POR15. I peeped inside the tank and everything looks sparkling clean. It seems unlikely that the filter is at fault, so perhaps it's possible that one of the front fuel lines has a kink.

Other small items: DD mentioned the PCV valve. Here's something I didn't put together about my engine until today. While the car is a '71, the engine is a '73. I realize that what I thought was a PCV valve isn't. It's just a relief chimney, not unlike the flashback valve. Apparently, the '73 1.7 liter is supposed to have a PCV valve. It's a change from the '71. But I don't think this is actually causing any problems given that the motor is getting plenty of crankcase pressure relief.

I also noted that the electrical connector for the TPS fit loosely. The harness is new. Removing the connector I found that two wires had fallen out of the plastic connector. I thought for sure this would be my problem. But it wasn't. I secured the wires but it didn't solve anything. Most likely I loosened them accidentally when removing the elbow.

Finally I decided that I should't necessarily be trying to adjust my way out of all of this with the MPS. The system just shouldn't be that far out of whack. So I set the MPS back to the values from the pbanders site thinking that those values are far more correct than any of the goofy adjustments I've made to force it to run. Setting the MPS back to default values makes the engine almost too lean to start and idle.

This gives me pause. If my other faulty condition is that if I hit partial load the AFR soon leans overboard and sputters before recovering. Similarly, if I'm parked and rev the engine to 2500 rpm it will do it all day. Or 3500. Or 4000. But the second I let off the throttle the AFR pegs lean, the engine stumbles almost to a stall, and then recovers.

Does this perhaps sound more like a fuel starvation issue than a vacuum issue? I am confident at this moment that there are no vacuum leaks. Or a D-Jet component issue? Taking a step back and trying to wipe my mind clean, never mind what I've already tested. What would cause the engine to fall to a stall via a lean condition after letting up from the throttle?

WCR is in seven days. Ack...

And just because everyone likes glam shots, here's the beast we're dealing with as of this afternoon.

Click to view attachment

Click to view attachment

oh, my .......... I'm so glad I sold my last D-jet car 7 yrs ago

A D-Jet equipped 914 is a capricious mistress. She's like the sea. You can play in her, but you cannot play with her.

I found that it was helpful to back out the adjustment screws to yield more inductance. When I made the graphs of Henrys vs vacuum the curves that worked better had more inductance at a given value than that in the article. At first I thought I really wanted to save it all for WOT, but in the end you need the pulse length for rich and inductance increases the pulse length, so maybe moving the coils together by backing out the screws will help. My car, which is no longer stock because of compression and cam does not like the stock MPS settings.

Well, I like graph paper. But I'm not sure about my ability to repeat what you've done. While I'm waiting for the new fuel filter to arrive I'm willing to measure and graph things. I don't know what you mean by "graphs of Henrys vs vacuum." Is that a link or some methodology?

The graphs are replictions of what panders does farther on along the wep page. He tells you what to set at 0, 4 and I think 15 and 20 psi vacuum. but he also shows the changes in inductance with different vacuum on a graph as well as changes in induction with movement of the armature.

My basic finding was my coils were set too far apart with the adjusting screw too far in. But also I found that different units have slightly different inductance at 0 vacuum, which corresponds to WOT. If I have time I will write something up - I haven't found instructions for actually adjusting these on a real engine.

Best of luck

Okay. I'll make a graph.

The fuel filter just arrived, so here comes a gas bath. I also checked my CHT. It measures 2400 ohms cold (70 degrees today) and just a hair over 1 ohm ten minutes later once warm.

Hello,
You say you tried an ECU with the knob and it did not react when turned?
TPS not adjusted correctly, (Pelican is missing some info!)
With the TPS not adjusted correctly you will not get the idle and the AFR at the correct starting point. After the TPS is correctly set than you can adjust the MPS.
Also I understand that if your fuel pressure is erratic than your injection timing is off, (easy to do if you reposition the spark plug wires from the distributor off by 90*).
Tell me more about the engine, size, compression, cam and what other work has been done.
Also the open PCV is a problem, it needs to have some restriction, 3mm is best as the port for the PCV is just next to the MPS hose, variations in pressure will make the MPS do strange things.
Don't give up on the D-jet, still a good system.
Mike

Hello there.

I haven't plugged the newer ECU back in since last week just because this is the one I've had with the car heretofore, and I'm trying to keep things simple and not introducing unknowns. I'm not 100% sure that that newer ECU even works.

Frankly I'm at a very frustrating stopping point. I simply don't know how to proceed. If it were an option to bring it a shop and have them sort it out, that would fine by me. But no shop in Portland has any great skill or desire to work with the D-Jet. I understand that from a shop point of view, it's a black hole for billing with no clear path for victory.

If the TPS isn't set correctly, what besides the Pelican article would you suggest to adjust it? I have no problem pulling it and doing what needs to be done. The circuit board inside is new as of last year.

The spark plug wires and distributor are correct. I pulled the distributor a couple of years ago, disassembled it, reassembled it, and threw a Pertronix unit on it. The car ran quite well last year until it sat for the winter. The only part I've changed since then is the MPS.

I discovered yesterday that the car has no PCV valve. Just a crankcase vent on the oil filler sandwich that connects via a tube to the air cleaner. If I plug it, it makes no great difference.

The engine itself is a 1973 EA code 1.7 liter engine. The compression isn't super but is okay for now. The cylinders are all within 10lbs of each over, hovering around 125psi. I have no idea what engine internals have changed over time. If it has a goofy cam or larger P&Cs, I have no knowledge.

I spent the last couple of summers performing a D-Jet Do-Over, learning how to test and rebuild each component. The MPS was the last part to rebuild because rebuilding services used the wrong diaphragms or were prohibitively expensive. But then the rebuild kits became available and I was able to proceed. However, I'll admit that MPS completely confuses me. The more I read the pbanders page the more confused I get. I understand principles about vacuum, fuel ratios, differences in load for idle, partial load, and WOT. But when it comes to inductance, aneroid cells, etc., my eyes just roll back into my skull.

At the end of this I've lost several days worth of work and I still can't say for sure if this is a vacuum issue, fuel issue, MPS issue, TPS issue, or what. Like I said, super frustrating.

My idle adj knob didn't work until I installed a good MPS. I went threw 3 "good" ones before I got "the" good one. I don't think the knob works unless the engine is dialed in. Also, there was a discussion here very recently regarding the values that were posted at his site. One of our electrical gurus had questioned something that was waaaay over my pea brained head. Search the last 60 days for it. Bottom line was that it would get you close. Re: your lean condition. Have you tried turning the smaller inner screw CC about 2 degrees.

Yeah, I saw that. Over my head also.

In fact, I have to turn my inner screw 1.75 full turns to get it to idle at 14:1. It's just for testing.

And..... DONE.

So all of the sudden there's a serious oil drip under the #4 cylinder where it was dry just yesterday. Right about where the head gasket is. The burning poof of smoke on the heat exchanger was a tip off.

Now that's an unpleasant discovery.

The oil leak is probably a valve cover gasket, or push rod tube seal.

There have been some problems with the new tps boards.
I installed one and it does not work. That could be cause is installed I'mproperly.
A few guys here with the same problem sent their tps'back to the guy who made them. He's a member here. I think it's Jim Kelly, but could be wrong about that.
He found some problems with them and fixed them. best I remember, it was a ground problem.

Henry's Law: "At a constant temperature, the amount of a given gas that dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid."

Oh wait, Faraday? It's a scientific fact proven in the early 1900's...

Remove your plenum. Hold it up to a light. I wonder if you have pin holes in the bottom creating unmetered air.

I believe it was Dave Sprinkle that was making the TPS board replacements...there's a listing for him
in the Member Vendor section.

It was Dave Sprinkle but I believe he said in the first post he replaced and properly set the TPS.

following with interest.....

Comrades,

My engine is a salad of despair, shooting out oil from cylinder #4 under the pushrod tubes. Top it with the bacon bits of misery because cylinder #3 now shows 90 pounds of pressure. It could very well be that I've been trying toss around the D-Jet in order to compensate for an engine failure. I can guess that this would be where any vacuum leaks came from.

It's clear that my path now is to rebuild the motor. I don't have the money, skill, or experience but as ignorance has always been my best weapon, I shall continue merrily down this path. My goal now is to break the motor down to see what I have, and if the guts look okay I want to rebuild it as a 1911.

Some of you may know I bought a 1965 Corvair engine for a conversion, but I've stepped away from that idea.

Luckily, one of my best friends is a machinist and rebuilds motors all day long for a living. I'll at least have someone to guide me and check my work.

Bad news. Despite weeks of anticipation and work on the car, I'm out of WCR this year. My car goes back into the garage for another year or two whilst I continue my plans.

But just for kicks today I rode my '71 BMW motorcycle out to The Dalles, Oregon on the old highway and it was absolutely beautiful. If you WCR attendees have never been to the Columbia Gorge, you're in for a glorious treat.

Thanks for everyone's input. Invaluable as always.

-m.

Sorry to hear your engine puked. I was watching your thread as I also have a Djet with a 1200-1400rpm idle that I had given up troubleshooting and learned to live with.

Don't let the set back prevent you from coming to the WCR. Bring the bike out again.

Come find me. I'll buy you one of Drew's beers and we can sit and listen to my high idle and ponder the mysteries of the D-jet.

I have rebuilt about 5 engines or so. Never been taught to do i. Bought the manual and some wrenches. The thing that gets me every time is that they start. Got no right to do it, but they do. So there is a yellow manual that is OK, Wilson's VW book that is indispensable, the Haynes manual which is really pretty good, a short free sample of the Mitchell online manual system that happens to cover the 914 engine, and the factory manual somewhat poorly scanned onto disc and available on ebay. Etc.
With those you should be all set. I think an adaptor for a cheap harbor freight engine stand is worth the money. Good luck amigo.

Hey Marcus, I found this thread because I, like MStein95, also have a 1400 idle (most of the time). 1) you're either very modest or don't realize what you did to assess the diverse and complicated potential causes is already WAY over the heads of most people these days, and we're talking well over 99%, so take it easy on yourself with comments like "pea brained" etc.

2) how did it work out for you in the end? Time for an update!

Mike in Munich

Yea that sucks big time,appears you had skilled up and knew your system well ,better that the guys that post saying "my car won't run" basically without them doing FA to research and find out why.
Good luck.

Hello there, time travelers! And also space travelers!

Am I the only one who remembers Jack Horkheimer?

I forgot about this whole thread but I can give you some supplemental information if you have nothing better to read.

When I bought the car it came with a bunch of glamor photos from 914club.com, claiming a professional engine rebuild. The whole car, and especially the engine, was done as a hack job from someone I suspect had spent a summer internship indentured to a Russian tractor factory with a side job of self-testing recreational pharmaceuticals for sailors.

After spending a solid year trying to differentiate my ass from speed-density, I found that loss of compression on cylinder #3 and that was a game ender. But I always wanted to rebuild a Corvair engine so I went that route instead. That was coming along super well until the machinist with half my parts disappeared. That crushed me a bit because I had a lot of money tied up with that. So I put that project on hold and moved instead to rebuilding my 1.7 liter. Somewhere out there will be a 914 roller just licking it's chops for that 3.0 liter Corvair engine. If anyone cares, I actually do plan to reboot the Corvair engine project but not soon.

Reverting to the 1.7 with it's stupid out-of-the-way lifters, I got as far as tearing it all apart and thoroughly inspecting the pieces and discovered that the year long D-Jet adventure was merely a sideshow. My first surprise was that the engine was actually a 1911cc and that explained why when it was running it was the best running 1.7 I had ever driven. However, the engine had been assembled wrong by the nine-fingered tractor factory intern. First, they didn't do any work on the heads to increase the valve sizes, so all that extra displacement was wheezing with teeny tiny valves. Then I found that they used a super mild carburetor cam from a bus. I also found problems with far out-of-spec piston and rod weights, crappy valves, and on and on. Basically an alumin(i)um clockwork of angst and misery. All that work trying to tune around a bad engine was obviously impossible but it did teach me quite a lot about D-Jet. I'm stunned that it ever ran at all.

There's more, too. Before I realized that I had big bore cylinders, and before I tore it down, I replaced the injectors after testing the original yellow-top units as part the D-Jet troubleshooting process. They worked like crap and my friend Gary's Amazing Injector Contraption couldn't clean them sufficiently. Yellow-tops have been gone for a long time and I needed new replacements. At the time the prevailing knowledge was to use Bosch black-top injectors meant for 1600cc engines which were alleged to be compatible. Perhaps they are. I'll never know. What I can say with certainty is that they aren't going to provide enough fuel for a 1911.

Remember all that trouble I had with constant super lean conditions? Well, I'm sure that was largely from the black-top injectors unable to provide enough fuel. When I had the whole D-Jet system mounted on a workbench I started comparing part numbers from the Paul Banders website. Sure enough, the ECU was from a 2.0 liter as was the MPS. That really threw me. After I had rebuilt the MPS and I was sure it was bench adjusted correctly, I spent some time on a desolate loop roadway making many stop-and-go adjustments to dial it in. That obviously never worked. When I found I had the wrong ECU, I swapped in a correct 1.7 liter unit but it just made things worse in that now I had a whole new galaxy of baseline values and reactions. That's about when cylinder #3 blew out.

Soooo my previous salad analogy was more apt than expected. From what I gather the borshch-slurping alcoholic with misspelled tattoos who put the engine together either didn't have any idea what they were doing or they just threw it together from parts found from around the house.

(disclosure: I lived in Russia for years but never visited any tractor factories - my loss).

Finally, in disgust I disassembled the engine and discovered all of the above faults.

Then, just for kicks, I took a two-year medical vacation to swap out my bone marrow. I was unhappy with the results since I didn't re-emerge any taller or more handsome. That sucked. I had such high expectations. Not even x-ray vision or telekinesis. What a rip-off! When I complain about this lack of features to my foxy oncologist she just stares back at me with barely restrained disgust. "Something something something saved your life something something," she says.

So where are things now? I forgot most of the D-Jet stuff I learned but I still think it's pretty cool. The main problem with it is just that the parts are getting worn out and replacement parts are getting increasingly scarce and old. The new MPS and TPS kits are great but they weren't available for the longest time. A Megasquirt replacement would be great if there were a suitable throttle position sensor (and injectors!). Maybe with all the 3D printing and CNC stuff the kids are doing then hopefully the picture might change.

Now that I'm well-ish(*) I plan to film the entire 1911cc to 1911cc conversion and put it on YouTube. Sadly, it won't show the tear down since I never filmed that. The disassembly/autopsy is one of the most important steps in a rebuild, so the video series will be confined to a thorough engine assembly process. I'm positive that the comments section will be full of reasonable opinions, researched statements of fact, and well-worded questions with excellent grammar and punctuation. I'll start that this coming autumn. I have all of the parts and the machine work is all finished so it just needs to be put together.

What about the D-Jet? Well, even though I still dig the system I ended up buying a perfect pair of Dellortos. So on they'll go. I've thought about selling the D-Jet system as a whole functioning package but the fact is that even though all of it is rebuilt, happy, and clean I've never seen it work because the engine was so messed up. For kicks, I might build an engine test stand and see if I can make it work (but only if someone donates known-good injectors). But the Dells will be installed following that. I know that even the Dellortos aren't as good or efficient at all speed, temperature, and altitude ranges as the D-Jet, but they have the advantage of being super stable. At the end of the day I like to dick around with D-Jet stuff, but the tow truck guy is getting sick of me talk about it.

-m.

(*) My oncologist reports the sad news that I'm the oldest and fattest I've ever been.

Thanks for sharing Marcus. Good read! Good luck!

If you're ever in Munich, get in touch with me. My company is Mike's Bike Tours.

All the best!

Is it really necessary to quote the entire Iliad and odessey one post below the original?

No sir, but it only takes up space on that comment and nowhere else. Should have deleted it though.

Enough depicting, time to build.

Thanks, dad. I'll build it when I'm ready.

Marcus...curious...what ecu were you running. Part No. ?

Sure. The last ECU I used was a 022 906 021 B unit that is/was correct for a 1970-1971 W-code 1.7 liter, but not for the 1973 EA 1.7 liter. Somewhere in my collection I have one for a '73 1.7 and a random 2.0 liter. But this one worked the best of the three, and I'm 90% certain that the 2.0 liter ECU was toasted when I bought it.

Ah, the joy of mismatched parts.

Quoted from your website bud......
Said with tongue firmly planted in cheek

It's all good. If you ever make it to Moscow I suggest you stop by the Alexandr Rodchenko museum. He was an amazing man.

I apologize for the snark.