D-Jet 2.0 Runs and then Doesn't - Troubleshooting, Trying to get my car to stay started Options

[Cessnaporsche01]

Hi all,

I've had this 914 for over 12 years now - bought by myself and my grandfather ( @JDW914 ) as a project back in 2011 - and used it regularly for a decade before a fire damaged a lot of the car's wiring and paint. It was re-restored 2 years ago, and hasn't run since, as we've had a lot of trouble getting it to stay running. I've finally taken full custody of the car and have been digging into trying to figure out this problem in earnest.

Where I stand:

The car is fully restored, and appears to be in strong working order. This is a nearly all-stock 1974 2.0 with an Original Customs 2056 upgrade. No other major changes.

- Compression checked at around an incredible 180# on all cylinders.
- Valve lash is at nominal on all valves.
- All fuel and vapor lines replaced with new.
- Fuel pump wiring replaced with 12AWG for more sturdiness, less resistance.
- Fuel pressure regulator replaced with new, added analog fuel pressure gauge in engine compartment.
- Fuel injectors (cause of the fire) were replaced with SMP FJ67s.
- Distributor cleaned and rebuilt, checked for responsiveness on ignition and FI points.
- All engine bay wiring has been replaced with brand new harnesses (and then meticulously rebuilt and checked for any issues after continued problems).
- Transmission ground replaced with brand new braided strap.
- The ECU (Type-044) (though somewhat charred) was tested by Specialized ECU Repair last year and given a clean bill of health.
- The MPS was replaced with a rebuilt unit correct for the car from a reputable community member.
- All minor engine sensors have been replaced with new and tested for correct responses.
- Throttle body and TPS rebuilt with new board, tested correct.
- Relay board was de-resin-ed, cleaned, and all joints were soldered, with all paths testing under 8Ω (seems a little high, but I guess that's just what solid copper gets you)

No matter what we've done, the car seems to die as soon as it's off the starter. It runs incredibly up until that point, then dies, but not immediately. Sprk continues, and it kind of sputters out. If spark is fairly retarded, it will sputter on for maybe 20 seconds before dying, which indicates spark is not an issue. And indeed, spark from a pulled wire stays strong to the very end.

However, it doesn't really respond any differently if starter fluid is sprayed into the intake manifold. This makes me think air mix might be an issue, but increasing air bleed seems to make it less eager to run rather than more. Additionally, The fuel pump is running, and the main injectors are most definitely firing, as the engine fires up every time, and the cold-start injector has been unplugged throughout my troubleshooting. The ECU has power on both pins 16 and 24.

2 other things do lead me to suspect some kind of fuel delivery issue, though: 1) The engine will run and stay running (BADLY and SMOKILY) with the CHT unplugged and open, and the spark VERY advanced. 2) When I move the throttle with the ignition on and engine off, I neither hear nor feel the injectors pulse.

Buuut, on the other hand, working the pedal while attempting to start the car normally will generally keep it alive longer, up to maybe 30 seconds, and pushing the car with ignition on, in gear gets a kick immediately upon spark, without running the starter circuit.

I intend to test the injectors by unplugging them and actuating the throttle to verify pulsing.

Does anyone have any advice on further tests to perform or ideas on failure modes this might be indicative of? Any sort of advice will be very, very appreciated.

This has been stumping myself, my grandpa, and every mechanic I've spoken with or had look at it for years, but I intend to figure it out.

[BeatNavy]

Wow, a lot of info. Ok, here's the obligatory link for obligatory reading: https://members.rennlist.com/pbanders/ (assuming you haven't already seen that).

It does sound like a fuel mixture issue. My first thought was bad CHT or break in CHT wire, but it's strange that the car will run AT ALL with CHT unplugged. The components that have the biggest impact on fuel mixture and can enrichen it to the point of flooding are the CHT (again, unplugged, bad sensor, break in wire, etc.), the MPS (blown diaphragm, unplugged connector), and cold start valve (leaking). Focus on troubleshooting those components and their continuity back to the ECU. Somewhere in that link above is a pinout of the ECU so you can test continuity on the wiring harness to all the critical components.

Once the car starts and runs (briefly), will it do it again or do you have to wait for a while? Or is there any other evidence that you're flooding the engine (e.g., wet plugs, smell)? What's your fuel pressure reading?

You're not going to hear the injectors "pulse" or click with the ignition on and moving the throttle. They are triggered by, well, the trigger points connected to the back of the dizzy. What you should hear are clicks from the throttle position sensor as you move the throttle, but that's not critical. The car will run with the TPS, just not as well.

(IMG:style_emoticons/default/welcome.png) I'm sure the collective wisdom here will help you figure this out.

[ctc911ctc]

".......as soon as it is off the starter........"

Do you mean it starts and THEN when you release the KEY out of the STARTER-ENGAGE position it dies?

If so, in 1974 I had a 1970 1.7 that had this problem - ignition wire in the ignition switch was the culprit.

Hi all,

I've had this 914 for over 12 years now - bought by myself and my grandfather ( @JDW914 ) as a project back in 2011 - and used it regularly for a decade before a fire damaged a lot of the car's wiring and paint. It was re-restored 2 years ago, and hasn't run since, as we've had a lot of trouble getting it to stay running. I've finally taken full custody of the car and have been digging into trying to figure out this problem in earnest.

Where I stand:

The car is fully restored, and appears to be in strong working order. This is a nearly all-stock 1974 2.0 with an Original Customs 2056 upgrade. No other major changes.

- Compression checked at around an incredible 180# on all cylinders.
- Valve lash is at nominal on all valves.
- All fuel and vapor lines replaced with new.
- Fuel pump wiring replaced with 12AWG for more sturdiness, less resistance.
- Fuel pressure regulator replaced with new, added analog fuel pressure gauge in engine compartment.
- Fuel injectors (cause of the fire) were replaced with SMP FJ67s.
- Distributor cleaned and rebuilt, checked for responsiveness on ignition and FI points.
- All engine bay wiring has been replaced with brand new harnesses (and then meticulously rebuilt and checked for any issues after continued problems).
- Transmission ground replaced with brand new braided strap.
- The ECU (Type-044) (though somewhat charred) was tested by Specialized ECU Repair last year and given a clean bill of health.
- The MPS was replaced with a rebuilt unit correct for the car from a reputable community member.
- All minor engine sensors have been replaced with new and tested for correct responses.
- Throttle body and TPS rebuilt with new board, tested correct.
- Relay board was de-resin-ed, cleaned, and all joints were soldered, with all paths testing under 8Ω (seems a little high, but I guess that's just what solid copper gets you)

No matter what we've done, the car seems to die as soon as it's off the starter. It runs incredibly up until that point, then dies, but not immediately. Sprk continues, and it kind of sputters out. If spark is fairly retarded, it will sputter on for maybe 20 seconds before dying, which indicates spark is not an issue. And indeed, spark from a pulled wire stays strong to the very end.

However, it doesn't really respond any differently if starter fluid is sprayed into the intake manifold. This makes me think air mix might be an issue, but increasing air bleed seems to make it less eager to run rather than more. Additionally, The fuel pump is running, and the main injectors are most definitely firing, as the engine fires up every time, and the cold-start injector has been unplugged throughout my troubleshooting. The ECU has power on both pins 16 and 24.

2 other things do lead me to suspect some kind of fuel delivery issue, though: 1) The engine will run and stay running (BADLY and SMOKILY) with the CHT unplugged and open, and the spark VERY advanced. 2) When I move the throttle with the ignition on and engine off, I neither hear nor feel the injectors pulse.

Buuut, on the other hand, working the pedal while attempting to start the car normally will generally keep it alive longer, up to maybe 30 seconds, and pushing the car with ignition on, in gear gets a kick immediately upon spark, without running the starter circuit.

I intend to test the injectors by unplugging them and actuating the throttle to verify pulsing.

Does anyone have any advice on further tests to perform or ideas on failure modes this might be indicative of? Any sort of advice will be very, very appreciated.

This has been stumping myself, my grandpa, and every mechanic I've spoken with or had look at it for years, but I intend to figure it out.

[Cessnaporsche01]

Wow, a lot of info. Ok, here's the obligatory link for obligatory reading: https://members.rennlist.com/pbanders/ (assuming you haven't already seen that).

It does sound like a fuel mixture issue. My first thought was bad CHT or break in CHT wire, but it's strange that the car will run AT ALL with CHT unplugged. The components that have the biggest impact on fuel mixture and can enrichen it to the point of flooding are the CHT (again, unplugged, bad sensor, break in wire, etc.), the MPS (blown diaphragm, unplugged connector), and cold start valve (leaking). Focus on troubleshooting those components and their continuity back to the ECU. Somewhere in that link above is a pinout of the ECU so you can test continuity on the wiring harness to all the critical components.

Once the car starts and runs (briefly), will it do it again or do you have to wait for a while? Or is there any other evidence that you're flooding the engine (e.g., wet plugs, smell)? What's your fuel pressure reading?

You're not going to hear the injectors "pulse" or click with the ignition on and moving the throttle. They are triggered by, well, the trigger points connected to the back of the dizzy. What you should hear are clicks from the throttle position sensor as you move the throttle, but that's not critical. The car will run with the TPS, just not as well.

(IMG:style_emoticons/default/welcome.png) I'm sure the collective wisdom here will help you figure this out.

Thanks! I'm intimately familiar with Brad's awesome write-up.

I agree that it seems like mixture related, and the CHT situation is strange. I just went out and re-verified as it's been a while since I did it that the car will run with the CHT unplugged. Not only does it run, but it runs pretty well, if rich enough to send some visible brown fumes out. Very little responsiveness to throttle in that state, though, just sputtering when I try to rev it.

The ECU harness has been very thoroughly checked, but I think I'll be reevaluating the MPS. Failing that, I'm a bit untrusting of the injectors.

The car will start and die as many times as I ask it to. The plugs look hot, but wet, and pretty normal for how this car's plugs have always looked after use. It doesn't smell too fuel-y. Fuel pressure is 28psi on the dot, but I've taken it as high as 40psi trying to test if it would respond to more fuel and the behavior didn't change.

Good to know on the injector/TPS front - I think I'd been mislead in my understanding of some old posts here.

".......as soon as it is off the starter........"

Do you mean it starts and THEN when you release the KEY out of the STARTER-ENGAGE position it dies?

If so, in 1974 I had a 1970 1.7 that had this problem - ignition wire in the ignition switch was the culprit.

Yes, but not so immediately, and spark does continue. I did think this could be the case for a while, but I've tested all the wires in the key/ignition circuit, and replaced the ignition switch with a brand new one with no change. While I was troubleshooting this, I also verified that the seatbelt relay bypass was still solid and not the source of my problems.

[BeatNavy]

Good to know on the injector/TPS front - I think I'd been mislead in my understanding of some old posts here.

My mistake, been too long on Microsquirt. That IS the sound of the injector clicking. You were correct.

Were the injectors new when you purchased them? Have you flow tested them or checked for leaks? Wet plugs sounds like way too rich.

[mgphoto]

Distributor is 180* out, been there done that, several times.

[r_towle]

Key in run position, does fuel pump run for 1.5 seconds?
Key in run position, is there 12 vdc at the positive terminal of the coil?

If yes, yes, run a jumper wire from battery to coil, positive side.
Will car now stay running?

Have you checked and validated the relay board? Those get bad.

[r_towle]

Distributor is 180* out, been there done that, several times.

I’m pretty sure if the distributor drive gear is installed correctly, it’s impossible to install the distributor off 180 degrees because the keyway is offset from center to prevent this on a type4

[r_towle]

Another test I would do to rule out ignition (spark)
Jumper to coil, positive side.
Hand held starter button, so I can do it while reaching in the engine bay
Starter fluid ether.

While key is on.
Jumper on coil
You are now fuel…continuos spray into throttle body the starting fluid
Short test, keep it running with no starter.
If that works….you are onto the fuel system.

[r_towle]

Fuel injector test
Get 4 small baby food glass jars (because they fit for this test)
Remove the 10mm nut on each injector
Pull the injectors out as a pair, place the ends into baby food jars so the jars will hold fuel (takes a little positioning, but it works fine)

Remove center wire on coil (remove from car, we don’t want a chance of a spark)

Turn over engine for 30-45 seconds
Go inspect each jar to observe the exact same amount of fuel

[porschetub]

Fuel injector test
Get 4 small baby food glass jars (because they fit for this test)
Remove the 10mm nut on each injector
Pull the injectors out as a pair, place the ends into baby food jars so the jars will hold fuel (takes a little positioning, but it works fine)

Remove center wire on coil (remove from car, we don’t want a chance of a spark)

Turn over engine for 30-45 seconds
Go inspect each jar to observe the exact same amount of fuel

Excellent advise,certainly starved for fuel .

[JeffBowlsby]

You’ve been through so much and apparently either overlooked something or it is intermittent. I would start from zero, trust no previous assumptions and be methodical. I have a couple djet test procedure lists on my Classics webpage, Tech Notebook tab, specifically the Kjell Nelin document. Go through that and you should find the issue.

[bobboinski]

I would check ignition timing. And even if it is correct bump it to 5 degrees more advance, just to see what happens. The distributor on one of my cars is worn and when it dropped back to full retard it would barely run. I had to adjust the stop (actually bend it) to keep enough advance at idle that it would run well.
Just a thought.

[emerygt350]

A very easy, no work first test could be whether the mps holds vacuum.

[mgphoto]

Distributor is 180* out, been there done that, several times.

I’m pretty sure if the distributor drive gear is installed correctly, it’s impossible to install the distributor off 180 degrees because the keyway is offset from center to prevent this on a type4

Haha

[rjames]

The MPS was replaced with a rebuilt unit correct for the car from a reputable community member.

If air fuel mixture is off- too rich or too lean to keep the car running, the MPS might the culprit.

[r_towle]

I’m not perfectly sure, but when I searched for a vacuum leak one time I removed every hose from the plenum and the car runs and idles fine.

Not sure if you need the MPs for idle….or start

[Cessnaporsche01]

Lot of responses, so I'll make my way down the list.

Distributor is 180* out, been there done that, several times.

I’m pretty sure if the distributor drive gear is installed correctly, it’s impossible to install the distributor off 180 degrees because the keyway is offset from center to prevent this on a type4

Yeah, I've double and triple checked the timing and made sure the timing gear was aligned correctly, as that was my first assumption based on the weird behavior.

Key in run position, does fuel pump run for 1.5 seconds?
Key in run position, is there 12 vdc at the positive terminal of the coil?

If yes, yes, run a jumper wire from battery to coil, positive side.
Will car now stay running?

Have you checked and validated the relay board? Those get bad.

Fuel pump does prime, and there is 12V at the coil when the ignition is on. I did still try running a jumper wire, but no effect on the engine behavior, so I'm still thinking it's not spark.

I did just go through the relay board last week - full rebuild and 100% check (as mentioned in the OP).

Another test I would do to rule out ignition (spark)
Jumper to coil, positive side.
Hand held starter button, so I can do it while reaching in the engine bay
Starter fluid ether.

While key is on.
Jumper on coil
You are now fuel…continuos spray into throttle body the starting fluid
Short test, keep it running with no starter.
If that works….you are onto the fuel system.

This does work. So reinforcing almost certainly fuel delivery is the issue.

Fuel injector test
Get 4 small baby food glass jars (because they fit for this test)
Remove the 10mm nut on each injector
Pull the injectors out as a pair, place the ends into baby food jars so the jars will hold fuel (takes a little positioning, but it works fine)

Remove center wire on coil (remove from car, we don’t want a chance of a spark)

Turn over engine for 30-45 seconds
Go inspect each jar to observe the exact same amount of fuel

Excellent advise,certainly starved for fuel .

Working on this one. Will update when I've got results.

You’ve been through so much and apparently either overlooked something or it is intermittent. I would start from zero, trust no previous assumptions and be methodical. I have a couple djet test procedure lists on my Classics webpage, Tech Notebook tab, specifically the Kjell Nelin document. Go through that and you should find the issue.

Thank, Jeff. That's more or less what I'm in the process of at the moment. I'll definitely read through the Nelin PDF.

I would check ignition timing. And even if it is correct bump it to 5 degrees more advance, just to see what happens. The distributor on one of my cars is worn and when it dropped back to full retard it would barely run. I had to adjust the stop (actually bend it) to keep enough advance at idle that it would run well.
Just a thought.

I've played with this quite a lot, and timing does improve the run time, but nowhere in the entire ~70 degree sweep I can access does it keep the car running, which is a stark contrast to how easily it will run at most any timing under ordinary circumstances.

The MPS was replaced with a rebuilt unit correct for the car from a reputable community member.

If air fuel mixture is off- too rich or too lean to keep the car running, the MPS might the culprit.

I'm starting to lean strongly in this direction. I'm definitely going to try to test the MPS next - make sure it holds vacuum and if I can get readings on it. The car had run twice with all the current parts, before starting this behavior, but I wonder if the MPS could have failed.

[r_towle]

MPs, FI trigger points, CHT, tps

They all determine when and how much fuel.

First test is to make sure all injectors fire ( baby food jars)
That eliminate FI trigger points and wiring
CHT is easy, use a meter
TPS is also a meter and visual.

MPs, initial test is remove hose, suck on end, will it stick to your tongue
If you must use a tool , very little vacuum or you will break the MPs

If you want, I will ship you the inline djet tester to help you sort it out….but a volt/ohm meter will get you there too

[BeatNavy]

If you are certain that ignition is not the issue then it has to be fuel delivery. You need to determine if it's fuel starvation or flooding, and then go from there. It can be surprisingly difficult to do that, I get it, but the suspects are different depending on the situation. Without a broad idea of what's going on you can't focus on likeliest of causes.

I'd consider doing the injectors-in-jars test to see if you're getting fuel delivery reliably and roughly equally at each injector. EDIT: Rich beat me to it.