Are my plug wires bad and if so would that cause stalling after the car is hot? - Page 12 - Alfa Romeo Bulletin Board & Forums
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post #166 of 302 (permalink) Old 04-21-2017, 01:43 PM
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post #167 of 302 (permalink) Old 04-24-2017, 07:30 AM Thread Starter
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Well, I was going to pick up the parts yesterday, but went to a wedding Saturday and everyone ended up with mild food poisoning. So I did not. Hoping over lunch today, though.

Wanted to give you a brief update. The car is running... somewhat. I've been messing with the AFM a bit - cleaned it, adjusted the little copper arms so they're on a clean track, tightened it up a bit, refit the contacts. I also removed the questionable ignition relay I installed a while back, just to eliminate it from the equation. Basically following advice from an MG guru I know - "What was the last thing you f*cked with?"

It'll warm up fine and even run smoothly if I have the idle up around 1500 or so. It WILL eventually begin to miss and stall. If I unplug the O2 sensor it'll smooth out. It's also running VERY advanced timing. It's set at the M mark on the crank and if I retard it at all it'll begin to miss and die. I confirmed TDC on #1 and the distributor mark is in the right spot, as are the cam timing marks. At this point it's running super rich - enough to burn your eyes - but that's the only way it'll run. High idle, advanced timing, no O2 sensor. I can pull/plug the retard vacuum hose and it'll jump up a few more degrees. All six injectors are firing (I can hear them clicking away using my stethoscope) and all six plugs are sparking. This has to be a mixture issue, right? Which would again come down to the AFM or ECU. There's no gas on the plugs although they're very sooty, and no gas in the cylinders after it dies. Starts easily without the CSI plugged in (I also confirmed it is NOT leaking).

Do you see a smoking gun in the clues?
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post #168 of 302 (permalink) Old 04-24-2017, 07:52 AM
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So... once it warms up, it will begin to miss and stall. Something is changing as it warms up, either electronics or otherwise. It sounds symptomatic of electronics breakdown, although I am NOT a EE.

Another thing you said, about the distributor, and the advanced timing-- if you retard it at all it begins to miss and die. That's pointing to something... not sure what, but might be another smoking gun. So, it will only run rich and advanced.

Maybe somebody else here knows, is there an air temp sensor in this Jetronic AFM, like on the Motronic systems?

I'm going back and re-read your post. Again.

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post #169 of 302 (permalink) Old 04-24-2017, 07:55 AM Thread Starter
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Yes, there is an air temp sensor in the AFM. It's in spec though, with regard to an impedance check.
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post #170 of 302 (permalink) Old 04-24-2017, 07:59 AM
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> is there an air temp sensor in this Jetronic AFM, like on the Motronic systems?

There is an air temperature sensor in the AFM - it is connected to the ECU.

(Doh. My post is a bit redundant) BTW - the undo the last thing you changed approach is unlikely to solve your problem - seems like your engine has been jinxed since day one. It seems to me that the best thing you can do is try a known good AFM and ECU to make sure they aren't the root cause of your problem.

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post #171 of 302 (permalink) Old 04-24-2017, 08:04 AM Thread Starter
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And to offer a bit of clarity, I'm adjusting idle simultaneously. I realize timing will be advanced with the engine idling high. After letting it run for a while, once I can tell the AAV is closing down, I start backing down the idle. Then move the distributor. Etc. If I even begin to approach spec - ~950-1000 RPM and/or crank mark on the R, vacuum will be tragically low and the engine will shut off.

As for the ignition relay, I didn't see the harm in putting the system back to factory. It was as simple as unplugging the brown wire from the trigger wire tot he relay and plugging it back into the back of the fusebox. Voila. I still WANT an ignition relay in place but for now I'm more comfortable with the stock setup.

I was reading on a Nissan forum that slack in the timing belt could be the culprit? But if the engine is at TDC on #1 with the distributor mark also on the spot, and both cams are aligning, AND it's running, then I'm not sure that could be my problem. My impression was that if timing slips it would be confined to a single cam. Unless it slipped on the crank, I suppose...

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post #172 of 302 (permalink) Old 04-24-2017, 08:10 AM
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Do you think maybe the distributor is off by a tooth? One tooth slow maybe? I don't know if there's enough adjustment on the body of the unit to make up for that. Maybe somebody else does...

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post #173 of 302 (permalink) Old 04-24-2017, 08:21 AM Thread Starter
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Possibly. It might've slipped? Although it was running fine for a while after the belt change, albeit with the occasional stall-when-hot, which was the ignition amp overheating (seriously, I plugged the original unit back up just to test it out and it was hot to the touch just sitting there without the car having even been turned on, so obviously an internal short).

I dug this up. It's FIAT L-Jet.
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post #174 of 302 (permalink) Old 04-24-2017, 04:09 PM Thread Starter
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Huh. Between 6 and 8 was 212 ohms, 7 and 8 was 258 ohms, and 8 and 9 was 203 ohms. Now, none were OVER the prescribed numbers in the the manual, but dang... they're really low. No real context for what I'm measuring though. Need other schematics to see that I guess.


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post #175 of 302 (permalink) Old 04-24-2017, 04:19 PM Thread Starter
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Are my plug wires bad and if so would that cause stalling after the car is hot?

Huh. So I have two spare AFMs. The first one produced similar numbers to mine. The second one, which was purported to be the best of them, produced numbers most similar to the manual, roughly 400, 800, 300.
I'm gonna try that one out.
Have two spare ECUs as well.


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post #176 of 302 (permalink) Old 04-25-2017, 10:35 PM
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fingers crossed - you need a dose of luck at this point I feel!

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post #177 of 302 (permalink) Old 04-26-2017, 07:31 AM Thread Starter
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Still haven't had an opportunity to really test this setup out. According to the L-Jet tuneup procedure, the multimeter test on the AFM is basically useless. I think the only way to really see what's what is to get it running, get is as adjusted as possible, then measure output from the O2 sensor.
Fingers still crossed.
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post #178 of 302 (permalink) Old 04-26-2017, 07:38 AM
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I think the proof's in the pudding. Just try one change at a time, to try to establish some cause-effect. I would change out the AFM, not do one thing else, plug in the connector, and start the motor. See what happens... and go on from there.

If nothing changes, then you can move on to the ECU substitute.

And I would use the second AFM... the one you got more normal readings from. I do not agree that the VOM readings basically are useless. Why would it be printed in the manual if it were useless information? Right?

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post #179 of 302 (permalink) Old 04-26-2017, 08:23 AM
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Quote:
Originally Posted by chairmankaga View Post
Still haven't had an opportunity to really test this setup out. According to the L-Jet tuneup procedure, the multimeter test on the AFM is basically useless. I think the only way to really see what's what is to get it running, get is as adjusted as possible, then measure output from the O2 sensor.
Fingers still crossed.
Have you opened the top of your AFM to inspect the tracks for the potentiometer? Perhaps they're worn in the idle area.

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post #180 of 302 (permalink) Old 04-26-2017, 08:50 AM Thread Starter
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I did, with my original one. I realigned the wiper arm a bit, moving it up a tad and bending the arm to make contact in a different spot. Cleaned the track. Added the ground strap as recommended by the BMW and Porsche guys (image below is NOT mine, just one of many examples online). Checked the solder joints. Then just cleaned the fire out of everything. Made a little difference but still experienced the eventual stall, once I got the idle down to an acceptable rate and began backing the timing down. It's just running crazy rich. Massive amounts of soot on the plugs and watering eyes, even out in the driveway.

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