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914World.com _ 914World Garage _ Fuching DJet issues *SOLVED*
Posted by: rjames Jun 12 2019, 12:19 AM
Last summer all of a sudden my car wouldn’t stay running. If I could get it started the idle would hunt and the car would die unless I kept on the gas. Lack of power at times. All somewhat erratic.
Found that the MPS wouldn’t hold vacuum.
Replaced the bad mps with a known good one. Car idles high when cold (higher than I think it should ~1600 rpm) so AAR is good, then when it warms up idle hunts from ~900rpm to the point where it almost dies unless I open the throttle body bleed screw quite a bit and turn the ECU knob just a few clicks away from full clockwise.
So I did the following hoping to fix the issue:
Replaced all vac hoses including intake runner to plenum hoses.
New intakecrunner gaskets
Verified plenum isn’t leaking
New throttle body gasket
Installed NOS throttle body
Rebuilt the distributor
New condenser
Rebuilt injectors and flow tested
New fuel lines
Fuel pump is less than 2 years old
Set timing and dwell with advance disconnected
New CHT (resistance reads 1.7 w/engine off @70 degrees in the garage)
Calibrated the TPS, even unplugged it to take it out of the equation, didn’t change anything.
ECU matches the MPS (both correct part #s for a ‘75 2.0)
Tried a known good ECU from a ‘74, no change.
Feels like the MPS needs to be calibrated...but then again, these are all the same symptoms I had with the old bad mps. Replacement mps is from a Jeff B and was tested, but I haven’t retested it to see if it’s holding vacuum.
(Don’t have the necessary tool, but maybe that’s the next step)
Help! What am I missing?
Posted by: GregAmy Jun 12 2019, 05:23 AM
Just a note on "known good MPS"...I was having terrible driveability problems with my '74 2L, similar to yours, and tried pretty much everything. Tested the MPS and it held a vacuum. I was stumped.
I was lamenting my probs when the guys at Tangerine said, "rebuild the MPS". "It's holding a vacuum" I replied. "Rebuild the MPS". So I gave them the MPS to rebuild.
It transformed the car. Car drives great now.
Turns out the diaphragm was cracked (Chris showed it to me) but somehow it was holding a vacuum anyway. Oh well.
Posted by: BeatNavy Jun 12 2019, 06:00 AM
Based on hunting idle it sounds like you're running too lean. That would be first suspect, but you should try to identify the broad root cause and then narrow down from there. What can you do to test if it's fuel delivery (too lean or too rich) and not something else like ignition, charging system, or vacuum? I assume you don't have a wideband O2 sensor. Have you tried unplugging the T1 (ambient air) sensor to see if that has an effect?
You've done a lot, but I would also recommend:
1. Verifying fuel pressure.
2. Inspecting/cleaning PCV valve.
3. Inspecting wiring harness for cracks, shorts, cleaning grounds, etc
Posted by: Bleyseng Jun 12 2019, 07:53 AM
I can loan RichD my wideband to check the AFR on your car. I agree with checking the wiring harness.
I also have a Janbo Djet tester I can loan RichD to test your system.
Posted by: rjames Jun 12 2019, 11:04 AM
I just installed a wideband sensor on my car but haven’t looked at the readings yet since keeping it running at all has been a challenge and knowing that the air fuel mixture was likely way off because trying to keep it running requires openening air bleed screw on the throttle body quite a bit.
I will check the readings though.
Posted by: rjames Jun 12 2019, 11:13 AM
Based on hunting idle it sounds like you're running too lean. That would be first suspect, but you should try to identify the broad root cause and then narrow down from there. What can you do to test if it's fuel delivery (too lean or too rich) and not something else like ignition, charging system, or vacuum? I assume you don't have a wideband O2 sensor. Have you tried unplugging the T1 (ambient air) sensor to see if that has an effect?
You've done a lot, but I would also recommend:
1. Verifying fuel pressure.
2. Inspecting/cleaning PCV valve.
3. Inspecting wiring harness for cracks, shorts, cleaning grounds, etc
No PCV on ‘75 or ‘76 year cars- the hoses are connected directly to the air filter housing.
What is the T1/ambient air sensor located?
Posted by: BeatNavy Jun 12 2019, 02:33 PM
What is the T1/ambient air sensor located?
It's inserted into the top of the plenum and has a 2-wire connector on it. Disconnecting the connector opens the circuit, and ECU interprets that as the coldest possible ambient air temp and enrichens the mixture somewhat to compensate. Not nearly as much as CHT, but enough to normally notice a difference.
Definitely verify fuel pressure.
Posted by: IronHillRestorations Jun 12 2019, 05:18 PM
Trigger points
Posted by: 914_teener Jun 12 2019, 06:12 PM
Post a pic of your engine compartment.
Are you running a decel valve?
So your d jet setup is for a 74 2.0?
Posted by: rjames Jun 12 2019, 06:19 PM
I'm using the decal valve.
75 2.0 with smog removed.
Using '75 ECU, MPS and appropriate CHT sensor.
I just rebuilt the distributor and installed new trigger points- didn't change anything.
Fuel pump is new, but that doesn't mean it's working correctly or the pressure is set correctly. That said, if it runs at ~1600 rpm when cold for a few minutes, it seems unlikely there's a fuel pump/pressure related issue. no?
I'll try disconnecting the T1/ambient air sensor to see if that changes anything.
Measuring fuel pressure is on the list too now.
How do I tell if the distributer is working correctly?
It still feels MPS related to me...
Posted by: BeatNavy Jun 12 2019, 06:45 PM
If you disconnect the T1 sensor I just want to see if things get incrementally better. If so, that might suggest a lean condition (also possibly suggested by the hunting idle). From there you could look to the actual root cause. But without a wideband sensor or other info it's hard to tell what the actual situation is (too lean, too rich, neither), and so to some extent you're chasing your tail.
Normal MPS failure is toward a rich situation. Why do you think it's MPS related? MPS's are pretty easy to test.
When you installed the new trigger points, did you calibrate them at all?
Posted by: rjames Jun 12 2019, 08:34 PM
If you disconnect the T1 sensor I just want to see if things get incrementally better. If so, that might suggest a lean condition (also possibly suggested by the hunting idle). From there you could look to the actual root cause. But without a wideband sensor or other info it's hard to tell what the actual situation is (too lean, too rich, neither), and so to some extent you're chasing your tail.
Normal MPS failure is toward a rich situation. Why do you think it's MPS related? MPS's are pretty easy to test.
When you installed the new trigger points, did you calibrate them at all?
I have a wide band sensor. Will check readings tomorrow along with disconnecting the T1 sensor.
I suspect the MPS because this all started happening when the original MPS went bad.
Bought a replacement from Jeff Bowlsby that he tested and the same symptoms remained after install. Or maybe that’s a reason not to suspect the MPS.
How do I rule out the distributor?
Posted by: JeffBowlsby Jun 12 2019, 11:08 PM
Its frequently the case when the MPS is going bad...that the system has been adjusted to compensate for a failing MPS. Then when the new good MPS is installed...the system itself is not in adjustment and seems wrong. Fuel pressure is changed, the air bleed screw is changed, the ECU idle mixture knob is changed and who knows what else.
For example, it was not mentioned above that the fuel pressure was checked. Its basic and important so use a gauge and check it. Then balance idle sped with the air bleed screw when warm.
Is the cold start valve leaking? Test it or take it out of the system.
Are there any vacuum leaks...gaskets, fuel injector tip seals, the air plenum etc.?
All these can affect idle and mixture.
Posted by: rjames Jun 13 2019, 12:08 AM
Its frequently the case when the MPS is going bad...that the system has been adjusted to compensate for a failing MPS. Then when the new good MPS is installed...the system itself is not in adjustment and seems wrong. Fuel pressure is changed, the air bleed screw is changed, the ECU idle mixture knob is changed and who knows what else.
For example, it was not mentioned above that the fuel pressure was checked. Its basic and important so use a gauge and check it. Then balance idle sped with the air bleed screw when warm.
Is the cold start valve leaking? Test it or take it out of the system.
Are there any vacuum leaks...gaskets, fuel injector tip seals, the air plenum etc.?
All these can affect idle and mixture.
No vacuum leaks detected. see above for all of the items that have been replaced and/or checked already.
Cold start valve has been removed from the system to no effect.
Besides the bleed screw on the TB and the ecu knob, and fuel pressure, is there something else that could be adjusted for a failing MPS that would make the car undriveable with a good MPS? (All inection components are stock.)
Fuel pressure is on the list to check next.
Distributer is still in question.
MPS is still in question.
Wiring harness possibly, but seems unlikely.
Symptoms originally occurred when the MPS went bad. Seems unlikely that something would’ve happened to the wiring harness, distributor, or fuel pump/pressure or wiring harness at the same time.
Posted by: sixnotfour Jun 13 2019, 01:07 AM
food for thought
http://www.914world.com/bbs2/index.php?showtopic=338162&hl=
Posted by: rjames Jun 13 2019, 08:58 AM
food for thought
http://www.914world.com/bbs2/index.php?showtopic=338162&hl=
Plenum isn’t leaking.
Posted by: rjames Jun 13 2019, 01:47 PM
Ok, more testing = more results.
Distributor canister won’t hold a vacuum. Only the retard side is hooked up, and that will effect idle, (if I understand how it works correctly), but if I disconnect the retard hose and plug it at Bothell the TB and the dizzy, issue is still there.
So after finding that issue...
With all hoses disconnected and capped my AFR tells me that ratio goes from 14 to full lean in synch with the fluctuating idle.
I don’t have a tool to measure fuel pressure (yet) but I did stick my ear down by the fuel pump and it gets louder/quieter as the idle surges up and down. Hmmm... May have just identified the main culprit.
Hopefully it’s just a clogged fuel filter, or it could be a bad pump (even though it’s a new Bosch unit(which would $uck). I cleaned the tank and installed new sock a few years ago so that should be ok.
Can I run the pump without fuel for any length of time without damaging it to test it?
So...
Where can I get a good distributor canister? Are they rebuildable?
Posted by: BeatNavy Jun 13 2019, 02:03 PM
Good news is it sounds like you confirmed the condition (lean), and you are getting closer to the root cause (failing fuel pump or possible obstruction in the line somewhere). Fuel pressure gauge would confirm it's on that path. BTW, don't cap the ports at the canister. Those need to be able to move.
The stock pumps are somewhat cooled by fuel running through them, so running without would burn them out (at some point). Not sure about the newer Bosch units. I figured those are pretty reliable (I have been running one about a year now), but who knows?
I'm not sure about the canister. Either WTB for canister or bite the bullet and get a 1-2-3? It's pricey, but works like a champ. I'd work to get the fuel delivery situation resolved and then reassess the distributor.
Posted by: jagalyn Jun 15 2019, 12:29 PM
Found this series of D-Jet Articles online.
https://oldtimer.tips/index.php/en/d-jetronic/51-history
Posted by: saigon71 Jun 16 2019, 06:12 AM
You are running lean at idle. Try truning the ECU knob to the full clockwise position.
I don't know if it's the ethenol in the fuel or what, but my 914 idle hunts the least with mixture knob set to full right (clockwise).
I don't think this will fix your problem, but may improve it.
Posted by: ChrisFoley Jun 16 2019, 07:28 AM
my 914 idle hunts the least with mixture knob set to full right (clockwise).
This is a clear indication that the MPS is adjusted too lean.
When the MPS is properly adjusted, the best idle can be found near the middle of idle mixture knob range.
Of course I am assuming that no other FI problems are contributing to the lean running.
Posted by: JeffBowlsby Jun 16 2019, 07:58 AM
A lean condition may also be corrected by increasing the fuel pressure a psi or two, by eliminating vacuum leaks, unplugging TS2 sensor.
Posted by: rjames Jun 16 2019, 01:44 PM
The idle hunt isn’t a slight hunt. It’s from 1000 rpm to almost 0. The ecu and throttle body screw are adjusted to allow it to run that good.
Thinking about this more as I wait for a new fuel filter to be delivered, I’m starting to question fuel being an issue since when the engine is cold it idles high for a good couple of minutes. Then I remember that the fuel pump gets quieter when the idle drops.
I’m still going to replace the filter and check the pump while I’m at it and then we’ll see where I am at. If it’s not one of those, then I think it’s the MPS.
Posted by: rjames Jun 20 2019, 08:34 PM
Okay, problem remains after replacing the fuel filter and verifying the fuel pump is doing its job.
Some new info though that I can’t believe I didn’t notice before:
I verified the timing (again). It was slightly off. Vacuum line was disconnected and plugged. After setting timing and with the vacuum line still plugged, it idled steady at ~1800 rpm. No fluctuations in idle. As soon as I plug the vacuum line back into the distributor vacuum canister, the idle drops to 1000 and fluctuated between 1000 and almost dying. Remove and plug the vac line and it’s back up to a steady 1800 or so.
No amount of adjusting the throttle body screw will bring it down to 1000 with the vac line connected. I can get the idle higher, but not lower. The ecu knob is effective at only keeping the rpm stable at idle (as it should).
AFR reading reads a steady 13.4 when I the vac line is disconnected and plugged.
Does this mean it’s my distributor that’s the prob? I know the canister leaks, but shouldn’t it still idle around 1000 even with the dist vacuum line off and plugged? Does that point to an mps that is bad or needs adjusting?
Posted by: JeffBowlsby Jun 20 2019, 09:16 PM
No effect during adjusting the air screw points to a vacuum leak.
Posted by: rjames Jun 20 2019, 10:45 PM
No effect during adjusting the air screw points to a vacuum leak.
There is effect- I can increase the rpm, just can’t get it down past 1500.
If there was a vacuum leak, why would the rpms drop to 900 and fluctuate down to almost 0 when connecting the line to the distributor? Wouldn’t the rpms stay up? At least enough to keep it running without opening up the TB screw a ton?
Seems odd that’s it would do exactly what it did when my original MPS failed, especially after replacing all vacuum lines, gaskets, intake boots, injector seals, verifying no leaks in plenum and installing a NOS throttle body.
Posted by: JeffBowlsby Jun 20 2019, 11:15 PM
If the air screw is fully closed, the engine should shut down because it would have no air for the combustion process. When air is still getting into the intake from somewhere, it keeps the engine running when the air bleed screw is closed. This is 'free air' or uncontrolled air - air that should not be getting into the intake. A vacuum leak.
Posted by: rjames Jun 20 2019, 11:31 PM
If the air screw is fully closed, the engine should shut down because it would have no air for the combustion process. When air is still getting into the intake from somewhere, it keeps the engine running when the air bleed screw is closed. This is 'free air' or uncontrolled air - air that should not be getting into the intake. A vacuum leak.
Why do the rpms drop so much when hooking up the distributor? The RPMs don’t go above 1000 when the vac line is connected.
Posted by: jcd914 Jun 21 2019, 12:40 AM
If the air screw is fully closed, the engine should shut down because it would have no air for the combustion process. When air is still getting into the intake from somewhere, it keeps the engine running when the air bleed screw is closed. This is 'free air' or uncontrolled air - air that should not be getting into the intake. A vacuum leak.
Why do the rpms drop so much when hooking up the distributor? The RPMs don’t go above 1000 when the vac line is connected.
It is the vacuum retard that you are hooking up and when vacuum is applied the timing is retarded several degrees (I don't recall how many degrees).
Since this is all part of the original equipment and designed as a system, the engine should idle fine with the retard hooked up.
What is your timing set to?
Jim
Posted by: BeatNavy Jun 21 2019, 05:28 AM
I think you may also want to verify your vacuum lines are hooked up correctly.
Posted by: Spoke Jun 21 2019, 06:05 AM
Why do the rpms drop so much when hooking up the distributor? The RPMs don’t go above 1000 when the vac line is connected.
So a question could be what is the vac line to the dizzy doing to the timing? It obviously changes the timing such that when the vac line is disconnected and plugged the idle stays at 1600RPM.
When you plug the vac line and idle stays at 1600RPM, have you tried adjusting the timing to reduce the RPM?
How did you verify there are no vac leaks? Did you spray carb cleaner on everything with the engine running or do the smoke test?
Is the AAR closing when warm?
Posted by: rjames Jun 21 2019, 03:55 PM
AAR is good.
Eschewing vacuum leaks for a second…
Questions about the distributor operation under current conditions. Bare with me…
My distributor vacuum canister is bad- but will hold vacuum for a second.
So the advance plates move with retard line connected (retards timing/slows idle) but because the canister leaks, the advance plates return to their resting position quickly even though vacuum is still applied.
This would explain why the RPMs drop to the correct RPM when the line is hooked up (retard is applied) and why the idle doesn’t hold steady (canister can’t hold vacuum; timing doesn’t stay retarded), but not why the idle drops to almost 0 RPM, vs going up when the timing is no longer being retarded.
Shouldn’t the idle go up well past 1000 RPM when the canister stops holding vacuum? (retard not applied anymore, timing is advanced), especially if there was a vacuum leak? If there was a vacuum leak, why would it even drop to the correct idle speed when I first hook up the vacuum line? Wouldn’t it always remain higher than ‘normal’? My AFR reads full lean when the idle drops to almost 0, and the idle drops when the distributor canister can’t hold (retard) vacuum. The engine almost dies, and then retard vacuum is available again (canister diaphragm is 'reset' and holds vacuum for a second) , RPMs go up, and then the dance repeats itself.
Could the distributor be directly or indirectly responsible for the drop in idle when it can’t hold vacuum for retard? Is there a way I can rule the distributor out of the equation besides installing a new one?
Posted by: 914sgofast2 Jun 21 2019, 07:42 PM
Sounds like the source of your vacuum leak is the bad distributor advance/retard can. Put another one on the dizzy that will hold a vacuum on both the advance and retard ports, and your problem should be solved. Djets are extremely sensitive to fantom vacuum leaks.
Posted by: rjames Jun 21 2019, 09:34 PM
Playing with it again, now it only idles high when cold. After idling high (AAR is working), it warmed up, dropped idle to 1200 rpm and held there for a minute or so. Then it did it’s usual go from 1000 rpm then drop to almost 0 unless I opened the throttle body bleed screw quit a bit. This time it didn’t matter if the hose to the vacuum canister on the distributor was connected or not.
Now it runs for a few seconds with the idle fluctuation and dies after a few cyclyes.
If there was a vacuum leak it would idle high, right?
Could this all be sign of a bad distributor? (BTW, I verified the MPS holds vacuum).
Ugh.
Posted by: 914sgofast2 Jun 22 2019, 10:46 AM
In my experience a vacuum leak causes the idle to hunt as the mps tries to adjust for it, resulting in your symptoms.
Posted by: Rand Jun 22 2019, 01:05 PM
I'd say not dizzy. The thing about the dizzy that affects idle timing is the vacuum ports / advance plates. You've been through that. Or have you? The gunk between the advance plates can cause intermittent sticking. Might need to take it all apart, clean, relube, and try try again. (I've been through that and can share pics and tips if you go there.)
Seriously at this point, just get a 123 dizzy. Even if it doesn't solve your problem, it's an upgrade you'll be happy with. You won't regret that expense even if it only rules out problems.
Posted by: rjames Jun 22 2019, 05:09 PM
I'd say not dizzy. The thing about the dizzy that affects idle timing is the vacuum ports / advance plates. You've been through that. Or have you? The gunk between the advance plates can cause intermittent sticking. Might need to take it all apart, clean, relube, and try try again. (I've been through that and can share pics and tips if you go there.)
Seriously at this point, just get a 123 dizzy. Even if it doesn't solve your problem, it's an upgrade you'll be happy with. You won't regret that expense even if it only rules out problems.
Rebuilt the distributor trying to fix this issue. A 123 dist is in my future but need to figure this out this first.
Will try looking for vac leaks if I can keep it running long enough.
Although I don’t see how it could be a vac leak if the rpms are low and it won’t stay running. Idle should be HIGH with a vac leak, no?
Posted by: rjames Jun 22 2019, 09:59 PM
Any chance this is a compression issue?
Posted by: Rand Jun 23 2019, 01:17 AM
Any chance this is a compression issue?
It ran fine. No. Unless there are unspilled beans.
Posted by: rjames Jul 5 2019, 07:21 PM
Updates and new info:
Installed new coil and 123 ignition distributor. Install was cake thanks to posts by others here.
Homemade smoke machine revealed 2 vacuum leaks which have been taken care of.
Current situation: I am able to get the car to idle at a steady 1200/1300 rpms. AFR is ~13.
The only way I can get the idle lower is if I move the TPS counter clockwise, but as soon as I do that, the idle drops to almost 0 and maybe comes back up a bit once or twice and then the engine dies as the rpms drop again. Calibrating the TPS puts the idle at 1200/1300.
The ECU knob will change the enrichment when the tps is adjusted to iallow a steady idle at 1200rpm.
When it’s at 1200 rpm the throttle body idle screw won’t bring the rpms down any further.
No vacuum leaks under the butterfly. If I take the air cleaner off and cap all lines, I can easily get the car to die by closing the bleed screw, indicating no vacuum leaks.
So could my TPS be bad? Is there a condition by which it could not allow a correct idle? Was thinking maybe I tweaked one of the contact arms when I cleaned the board. Looks ok though and the board is in good shape.
Or am I in MPS adjustment territory now?
Posted by: BeatNavy Jul 6 2019, 04:36 AM
Just to be clear, I believe there's only one setting (not adjustment) for TPS - it's either calibrated correctly or it is not. It is easiest to do it by removing it, but I have done it while still mounted on TB/plenum. I don't think that's your issue.
What curve are you using for the 1-2-3, and are you using advance or retard on the port?
FWIW, once I installed the 1-2-3 I noticed that the idle speed was very sensitive to fuel mixture compared to the other dizzy that came with this engine (which was not correct, it turns out). With the 1-2-3 it does idle rock steady, but no matter what I do I really can't get idle below 1000 even with bypass screw all the way in. I try to run idle A/F around 13.5 to 14.5 to keep it steady around 1000. If I go richer than that I get idle closer to 1100/1200, IIRC. Much leaner and it will start to hunt. I also chased vacuum leaks for a long time, to the point of swapping out plenums and trying to spray carb cleaner everywhere, but I never found anything.
I can't recall, is this stock 2.0 or 2056? If stock, and the MPS holds a pretty steady vacuum and is correct for your ECU, then that shouldn't be the issue.
Posted by: rjames Jul 6 2019, 08:59 AM
Stock 2.0 liter with correct/matching FI parts. MPS holds vacuum.
113 dizzy is set to ‘B’ to retard the timing at idle (like my stock setup).
If vacuum leaks are gone, seems like that only leaves adjusting the MPS? Before my old MPS went bad, the car idled at 900 rpms.
Posted by: rjames Jul 14 2019, 07:42 PM
Beyond frustrated now.
Started again from the beginning- timing.
My fan only has a single mark- a red one, notched at 7.5 degrees from TDC. I can’t find any other evidence of another fan like mine.
I guess maybe I’ve been tuning it from the wrong mark for the last 10 years (?!) as back then I used pelican’s template to find the 27 advance mark off of the 7.5 mark.
Verified where TDC and 27 BTDC actually was. Car now starts and idles high when cold (too high) and then when it warms up it dies and won’t start again.
WTF? Before I could get it to idle, albeit high, now it won’t run after it warms up.
Setting the timing to where it was doesn’t change anything. I feel like it’s flooding when trying to restart. Engine seems hot- distributor gets too hot to touch after several attempts to restart it. Fuch this thing. Getting ready to push the car off a cliff.
Posted by: 914_teener Jul 15 2019, 10:06 AM
Stock 2.0 liter with correct/matching FI parts. MPS holds vacuum.
113 dizzy is set to ‘B’ to retard the timing at idle (like my stock setup).
If vacuum leaks are gone, seems like that only leaves adjusting the MPS? Before my old MPS went bad, the car idled at 900 rpms.
Send us a picture how you have routed your vaccum lines to the 123.
My quess is that you are using manifold vacumm instead of ported vacuum.
Post a pic.
Posted by: rjames Jul 17 2019, 12:27 AM
Stock 2.0 liter with correct/matching FI parts. MPS holds vacuum.
113 dizzy is set to ‘B’ to retard the timing at idle (like my stock setup).
If vacuum leaks are gone, seems like that only leaves adjusting the MPS? Before my old MPS went bad, the car idled at 900 rpms.
Send us a picture how you have routed your vaccum lines to the 123.
My quess is that you are using manifold vacumm instead of ported vacuum.
Post a pic.
123 retard is connected to the retard port on the throttle body. There is no advance port on the throttle body on the later cars. That said, issue is the same even if the hose is disconnected from the distributor left unplugged.
Posted by: rjames Aug 17 2019, 06:55 PM
Issues fixed. Had multiple things going on. Distributor vacuum canister leaked. Replaced with the 123 distributor.
Tiny vacuum leak ended up being a worn throttle body linkage shaft (at least that’s what I’m calling it). Was a very minor leak, but a leak just the same. It didn’t show up on the smoke test I did, but it did show up when I tried pressurizing the system. Replaced with a NOS throtyle body I found on ebay (got lucky there, price was reasonable, too). It doesn’t have the safety spring like the later models, but I doubled up on the TB return spring for piece of mind.
Engidlebidles at a perfect 950rpm.
Next step was to tune the air fuel mixture. The rebuilt MPS I got from Jeff had been reset to factory default settings, but was way too lean for my car as I had originally thought. I adjusted the MPS using Chris/Tangerine Racing MPS adjustment tools in conjunction with the Plex wideband sensor I installed last year.
My AFR is now 13.5 at partial load, and 12.5 at WOT. Idle is at 12.2. I may try bringing the idle mixture up a bit with the ECU knob.
The car drives fantastic. Having a steady idle after 12+ years of ownership is a thing of beauty. And just in time to enter the car into the Edmonds car show in Sept 8th!
What a journey! Although extremely frustrating at times, I sure learned a lot through the process.
Thanks for all the input/help from everyone!
Posted by: 914werke Aug 17 2019, 08:18 PM
Great news! Come on out tommorow for lunch at the Diamond Knot!
...with the car
Posted by: Tdskip Aug 17 2019, 09:22 PM
Excellent news
Posted by: rjames Aug 17 2019, 10:49 PM
Great news! Come on out tommorow for lunch at the Diamond Knot!
...with the car ������
Wish I could join you. Already had plans for a family gathering. I know these get together aren’t easy to make happen, but hopefully there will be another one soon.
Posted by: falcor75 Aug 18 2019, 05:01 AM
Congrats on solving it.
Posted by: BeatNavy Aug 18 2019, 05:25 AM
In addition to having a solid running car you now know a boat load more about it, particularly D-Jet. Hardest problems to solve are the compound ones, where multiple issues send mixed signals making the troubleshooting process a bear.
Way to stick with it, and congrats!
Posted by: 76-914 Aug 18 2019, 08:55 AM
Issues fixed. Had multiple things going on. Distributor vacuum canister leaked. Replaced with the 123 distributor.
Tiny vacuum leak ended up being a worn throttle body linkage shaft (at least that’s what I’m calling it). Was a very minor leak, but a leak just the same. It didn’t show up on the smoke test I did, but it did show up when I tried pressurizing the system. Replaced with a NOS throtyle body I found on ebay (got lucky there, price was reasonable, too). It doesn’t have the safety spring like the later models, but I doubled up on the TB return spring for piece of mind.
Engidlebidles at a perfect 950rpm.
Next step was to tune the air fuel mixture. The rebuilt MPS I got from Jeff had been reset to factory default settings, but was way too lean for my car as I had originally thought. I adjusted the MPS using Chris/Tangerine Racing MPS adjustment tools in conjunction with the Plex wideband sensor I installed last year.
My AFR is now 13.5 at partial load, and 12.5 at WOT. Idle is at 12.2. I may try bringing the idle mixture up a bit with the ECU knob.
The car drives fantastic. Having a steady idle after 12+ years of ownership is a thing of beauty. And just in time to enter the car into the Edmonds car show in Sept 8th!
What a journey! Although extremely frustrating at times, I sure learned a lot through the process.
Thanks for all the input/help from everyone!
A huge congratulations to you. I like your approach; check everything and repair it. Newbies take note: these are 50 year old cars. You cannot rely upon any 50 year old part. Looks like your good for another 50 now!
Posted by: Jett Aug 18 2019, 09:33 AM
Great persistence. My car is at Chris’s German auto and the more they touch it the worse it gets... I’ll have Chris call you to get this fixed 
Posted by: DRPHIL914 Aug 18 2019, 09:39 AM
Way to go!! Good for you for hanging in there. As usual
With d-jet it’s always related to the distributor, vac function and leaks, and the MPS. I have yet to see a MPS that once “set to factory specs” that has not been too lean and needed to be adjusted less lean. Sounds like you nailed it and those are good numbers!
Posted by: Rand Aug 18 2019, 04:11 PM
Thanks for sharing the solutions. Often people don't.
Posted by: ssuperflyoldguy Aug 18 2019, 11:03 PM
appreciate the write ups, diagnosis & help from everyone. So many threads on the internet never have closure (like what finally solved it) - Bonus, I have a 75, removing smog too but it's a 2.0 with Bus Heads - this thread will help me get mine back running (I hope, parked it a few years ago because it was running rough and I smelled fuel) have it up on jackstands finally and will install my stainless steel fuel lines soon!
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