Need some help figuring this one out.

1975 chassis with rebuilt 2056 D-jet, about 900 miles since build. D-jet components are matched 1974. Bowlsby harness.

Ran great last year, normal startup with high idle around 2000 cold, dropping to 850 warm. Filled it with nonethanol gas plus stabil for the winter and it sat about 6 months on a battery tender this winter.

Hasn't started right since getting it out of storage a month ago. Main symptom is that it dies repeatedly cold. It will start fine and with ZERO hesitation on the first start EVERY time cold, but will die randomly within 15 seconds. It does not stumble; it just completely cuts out. It becomes harder and harder to re-start after dying; usually will start fine again on the second try, will again die randomly after a few seconds. The third start is then really hard and it will need full throttle and a good 15 seconds of cranking before it will start; then it dies again. Every subsequent start is a hard start and it will need full throttle. If I let it sit 10 minutes, it will start easy but again dies just like before.

It always dies the same way; it completely cuts out; no miss, no stumble, RPMs just drop to zero. It will cut out at idle and will cut out with throttle; doesn't matter if its at 1000 or 3500 rpm, it randomly cuts out the same way.

It will keep doing this until it gradually warms up (might take 30 minutes to get it warm enough to stay running). When it is warm it runs 100% fine; does NOT die, stumble, miss, or cut out, and I can drive it all day like this. It will restart fine warm. It's only cold that it won't keep running.

The other weirdness is that warm-up idle is no longer working correctly. The car will not idle high cold any more. It will sit right at 800-900 fully cold, regardless of ambient temp. Last year it was idling normal cold, around 2000, gradually coming down to warm idle. Doesn't do that anymore.

I've really thought this is most likely a CHT problem but I've checked and rechecked it and CHT seems fine. I've checked it at the single spade connector and also at the ECU and the ohms match. It reads about 2800 cold and under 100 when fully warmed up. I tried adding 500 ohms to the CHT with a potentiometer and it didn't change anything.

AAR confirmed to work normally. Again, it will die at idle and with throttle. No difference.

Valves were set about 300 miles ago. It's currently timed to 26.5 degrees BTDC. I retarded it a little from the prior timing of 29 thinking maybe it was too advanced but no improvement.

I've swapped voltage regulators; unplugged and replugged all the FI connectors. Again it has a rebuilt harness.

Fuel pump is working and my inline gauge is reading 34 cold. I've tried moving the pressure up and down and it doesn't make any difference. Pressure remains above 30 after it dies so I don't think its a fuel issue. ECU knob has always needed to be almost full clockwise to idle smoothly. It's been like this since rebuilt so I've just taken it to be a characteristic of the 2056.

It's stock D-jet except for 1) Pertronix ignition 2) Odyssey PC925 AGM battery 3) that GB kit that was offered years ago which adds four fuses to the positive lead coming off the battery. All the fuses are OK. No other electrical problems and all the cabin electrics stay on when it dies.

A little weirdness with the battery in that my charger is repeatedly flashing "bad battery" if it charges for more than a few days. However, I'm getting 12.9 volts at the battery and it's turning over just fine. I've sort of assumed the harbor freight charger is the issue - but could this be the AGM battery going bad? Alternator light goes out normally when started and the center console volt gauge seems OK - fluctuating between 12-14 when cold then going to 12 when it dies. Cranks totally fine, even for protracted cranks.

No vacuum leaks that I can find. I haven't touched the MPS as the builder had it tuned for this engine.

Open to any other ideas.

Yes.

You have an electrical connection somewhere that is critical that is loose when cold and then when the connection warms is okay.

I'd start with a DVM and ping out each on the FI Harness for resistance when cold.


Also, and one of the most overlooked connection is the multispade connector under the plenum that grounds to the case. If you have never cleaned it, check all those connections. If you have a new harness should have been done then.

"AAR confirmed to work normally"

Doubt it. Check that AAR again. Its what creates the high idle when cold.

Hoping to learn something here. Jeff, would the AAR cause it to die? I know if affects idle speed, but how would it cause it to suddenly die?

Hoping to learn something here. Jeff, would the AAR cause it to die? I know it affects idle speed, but how would it cause it to suddenly die? No stumbling, just dies. That sounds electrical to me. Does a failing AAR cause shorts or somehow something electrical?

Yup, want to confirm that engine quits at all throttle positions and at all engine speeds, only when cold. Start it, rev to 2000 --> OK for a couple seconds, then dies. Start it again, rev it to 4000 --> same thing.

My AAR isn't perfect. There is some restriction with the AAR in that, when I can get it running for more than a few seconds, the idle will go way up when I pull the hose off the AAR. However I've bench tested it and it definitely is open cold and will close itself in approx. 5 min when 12V is applied. If I can get it running when the AAR is still open, I can block it off manually and see the idle drop so air is getting through.

FWIW, I've also tried backing the idle screw WAY out with no improvement. Right now the idle screw is about 3/4 of a turn out. It idles at 850-900 fully warmed up. Also should mention that I've tested the TPS and it is set correctly to close at idle.

I haven't tried actually starting it with the hose off the AAR. Maybe I should try that although it seems like it would be doing basically the same thing as revving it with the accelerator to 2500, no?

Good ideas, easy to check. thanks.

Question: when it dies and ignition is still on, green alternator light comes on and fuel pump is NOT running. Is this normal behavior or should FP keep running?

FP primes normally and pressure stays normal after it dies. My regulator is really good and it will stay above 30PSI for at least 10 minutes after shut off.

Does anyone know in the movie mad max

After the appocalips are they running carbs or f.i

Well, scifi and reality are a far stretch apart. No apocalypse yet. How many modern cars come with carbs vs FI? Why to you think that is?

Next time that it dies pull any plug & check for spark; also pull an injector (unless you have a noid lite) to confirm it's squirting.

skimming the first couple of lines, I would guess that the head temp sensor is not providing enough resistance

He stated he tested the unit and those resitance values are good George.

The car should run with the AAR plugged.

It is something else.

Ok....you don.t mention spark.

Try swapping a good dizzy in.

You're still here?

I.m still deciding on my next name.

I.ve decided on my license plate for the new Croc but it won.t be ready foe the WCR.

You.ll miss me Kent.

The pump only runs when the trigger points tell the FI that the engine is running over about 25 RPM. (125?) So if the engine dies, the pump stops running. That is a deliberate design.

The "idle screw has no effect" makes me think that you have either a very rich or very lean mixture.

--DD

Dave - just meant that it continues to cut out randomly cold whether the idle screw is in or out. RPMs do come up when idle screw is out. I don't doubt that there may be mixture problem however.

Checked for spark - NO SPARK when it is cranking after it cuts out. I get spark and it runs for a couple secs then dies, then no spark again.

Noid light on injector #2 checks out OK with injector pulses while it is cranking.

video of spark test

https://www.youtube.com/watch?v=DwxmAsUUCEk

Well there is your answer.

Get a 123 dizzy and don't look back.

Pulled the distributor and found at least 1/4 inch of axial (up/down) play. Fiber washer completely disintegrated.

Guess my builder used compufire instead of pertronix to replace the points. Followed the compufire testing procedure and found that I get a solid 12V cranking instead of the voltmeter alternating between 1 and 12V. According to the testing procedure, this would mean one of the leads isn't connecting to the coil; except, I recrimped them, reattached them, no change.

Which leads me to think the compufire unit is the main culprit. It must have an open circuit somewhere that closes when it warms up. The axial play might be causing the excess scatter I saw when I timed it last. Who knows if its contributing to the no start but it's probably not helping.

The blue coil is testing 3.6ohm on the primary and 8.6kOhm on the secondary. I have no idea if that is within spec (seems a little high on the secondary) but I kind of doubt its causing the starting problem.

Guess I have to pony up for a rebuilt dizzy. $$ for the 123 ignition is kind of steep. It's about 1/3 as much to get a Cardone, swap over parts, live with points. Is the 123 really worth it?

Yes.

SOLVED.

Bad compufire unit in the stock dizzy.

Upgraded to 123 Ignition model per 914_teener's rec. Starts great, runs great. Idle is ROCK solid. Very impressed with this product.

Also - opened up my AAR and adjusted it so that it's a little more open cold. Idles at 1600rpm now cold. Fixed my stumble problem on cold start. I don't need to give it any throttle at all on cold start now.

Found that setting "2" on the 123 Ignition dizzy caused the car to idle too high. Couldn't get it below 2000 RPM warm. Switched to "B" and it runs normally. Can't say that I really understand why it idles lower on "B" - can anyone with experience elaborate?

What cam are you running and are you running vac advance?

I had the exact same experience. Curve B (I believe) is for later 2.0 models that did away with vacuum advance. You just need to plug that hose connected to the plenum. You should only be using retard, and that's what will bring your idle back to normal (and rock solid) range. I initially had it on curve 2 and kept thinking I had a major vacuum leak somewhere.

I love the 1-2-3. Been running it since Rob (914_teener) shepherded us through that group buy more than a year ago. A couple more observations about my experience ('74 D-Jet components, 2056, stock cam): I almost can't get the idle any lower than about 950 even with idle bypass all the way in, and then the idle is pretty sensitive to fuel mixture (e.g., if I change the ECU knob setting). '

Anyway, rock on from here!

Rob is of course correct! Hi Rob!

Been there done that....both of us.

I've had the exact same experience too and have been battling a high idle problem for about 6 months after I rebuilt the engine. I kept thinking I had a vacuum leak somewhere but after spending countless hours on checking EVERYTHING, I know I don't have any leak issues. I also bought the 1-2-3 and put it on curve 2. I'll try the other curve now. Hopefully it will come down. BeatNavy, I am not sure I understand the retard statement. My 1-2-3 dizzy only has the advance function, which I hooked up as it states in the directions, can you elaborate on this?

Cheers,

Brian

The 1-2-3 comes with only one hose port, IIRC - it can either be used for retard or advance, depending on your application. Instead of hooking it up to the advance port on your throttle body, hook it up to the retard port. Cap/plug the hose on the advance port at throttle body. Use curve "B" in this scenario. If your application is like mine that will work nicely for you. Without the retard function at idle, your timing is too advanced causing the high idle.

My understanding, someone will correct me if wrong, is that late model D-Jet's did away with the vacuum advance and simply relied on mech advance. My car is a bit cobbled together: it's a '72, but it has a 2056, and the D-Jet was largely from a '74. But the dizzy wasn't right at all, and when I purchased a rebuilt throttle body it actually had the advance port plug welded (or something). At this point I believe my D-Jet is pretty much all '74 (if you count the 1-2-3 with the curve set to "B").

Thanks, that's good info. I've currently got the vacuum hooked up to advance (like with the stock distributor) but will try to put it on retard to see if that changes anything. Really it seems to be running fine as it currently is set up on the advance side. It does take longer than the old dizzy to "float" down to idle but I'm OK with that. I'm running a 2056 with a slightly more aggressive than stock Webcam.

I'm really impressed with the ignition stability with the 123 - the car just sounds better overall both at idle and in the higher revs. Build quality is excellent and it was super easy to install. Appreciate the tip.

Yeah thanks for the information! I am gonna try swapping the 1-2-3 to "B" port this weekend as suggested and reset everything. Hopefully it will cure the high idle. I'm stoked because it runs like a new car other than that!

Cheers,

Brian