Oddjob

Two years ago, 89 Turbo had an episode of dying/stalling while moving. Car would feel like it lost all power (throttle response - not electrical power) while moving and would slowly die. It did this 3-4 times over the course of a couple days. It restarted while still rolling, all but one time. That one time it died, would restart and run a little, then died completely. Left me on the side of the road. It smelled like gas and it had also backfired, so I thought it was running too rich. Tail pipe and bumper were black/sooty – more than usual. Swapped the DME relay (which normally kills the fuel pump) and I checked for spark, which was visible (pulling a plug and cranking it over). Thinking that it was getting more gas than air – I disconnected the TPS, with the quick thought that it was incorrectly telling the DME that the throttle was wide open (I don’t think this is correct logic because the AFM should be telling the DME the air flow and indirectly controlling the fuel delivery – but I was on the side of the road and running out of options, spares, and tools). The car started, drove it home, replaced the TPS and the problem was gone – at least for 2 years.

However, this past weekend, the problem seems to have returned. Someone else was driving the car, so I did not witness the symptom first hand, but their description matches what I experienced two years ago, including the gas smell. It would intermittently lose power and chug while driving then it died two different times. One time it restarted immediately, the other time it would not, but did start and make it home several minutes later.

So the car either temporarily loses spark (or weak spark) and dies, or its getting too much gas and dies from running too rich? Either way it restarts after the excess fuel evaporates?

Possible a coil going out or bad coil wire connection? Problem with the DME? Reference Sensors? AFM?

Any input appreciated.

hally

Hi Jim,
I have experienced the following engine dying scenarios:
DME relay - from memory there was 1 backfire then no more firing.
reference sensors - intermittent, rich, black smoke, backfiring etc
AFM - intermittent, rich, as above.
TPS - failed when highway cruising, changing accelerator position would get it working again, moving the TPS off the failing spot.

Currently i have another undiagnosed intermittent engine dying problem, maybe someone also has ideas what this could be. The car idles and cruises great, correct a/f ratio dithering around 14.7, but sometimes when i give it some gas the engine dies quietly after a few seconds, no backfiring or black smoke. The best way i have been able to make it fail is revving to 5k rpm in first gear on an uphill road. As usual i have started out thinking it might be fuel related, tried my spare DME relay, that wasn't it. Did the fuel pump flow test from the manual and i got 1litre in 30 seconds. manual says 850cc with the 2.5bar fpr, though i am running a 3bar.. any ideas on this one appreciated also.

smokey

Have you checked the spark plugs? I once had similar symptoms from a defective plug.

R.B.

I had a similar dying, intermittant start problem, that finally left me at the side of the road. I resoldered my DME and haven't had a problem since. About 1 year now. If you acn borrow another DME, try swapping it and see if it runs OK.

R.B.

Oddjob

Thanks guys for the input.

I will look into the plugs. Other than the described problem, the car runs absolutely normal/fine - no missing or rough idle. And the plug wires are new. So I had not thought of the plugs causing a problem, but they are easy to check/replace, so will do.

I can easily swap out the DME (I have a spare), but of course (with all intermittent problems) it is running fine now. So I can swap parts and not know if the problem was solved or just in hybernation for another 6 months....

So the other option is to swap out everything, DME, reference sensors, AFM, coil, etc and call it a day (the only parts I dont have on hand are the reference sensors). What Im wondering is if, from my described symptoms, if I can rule any of those items out, and not worry about swapping or replacing. Can both reference and speed sensors lead to this symptom, or just one or the other?

R.B.

Yes reference sensors can cause intermittent start issues.

R.B.

hally

had any luck with your problem Jim?
Pretty sure i've fixed mine (hard to be 100% with intermittent issues), i realized that engine was cutting out on throttle lift off, checked my TPS and sure enough, only sometimes did the idle switch 'click' on throttle close. Adjusted it a fraction and no more problems to date. Have a vague understanding that the TPS closed switch is needed to switch the injectors back on once the RPMs drop down when you lift off the throttle, so that adds up.

Oddjob

Havent had time to play with it since and the problem, of course, is currently hiding....