jonfkaminsky

After my prolonged dash warning lights...fault 1134/1234...pinging issues were apparently all cleared up by the complete replacement of the battery, dist caps, dist rotors, spark plugs, and spark plug wires, I ran superbly for almost two weeks when suddenly the engine surged or cut out for a micro-second. Then it did again a few seconds later. The next day, this happened a few more times. A few days later, I barely made it home from work, the car was stalling and bucking so hard.

Now it cannot even idle without stalling unless someone is there playing with the accelerator to keep things going.

Taking a tip from Adrian's book, I tried jumpering across pins 3 and 7 of the fuel pump/DME relay which did turn the pump on. I replaced the relay nonetheless, and the engine will start with the relay in place, but as I mention above, it will stall without intervention.

It feels like the engine is not getting fuel but that is complete conjecture at this point. I can also liken it to hitting the rev limiter.

Help!!!!

jon

History:
https://rennlist.com/forums/showthre...1&page=1&pp=15
https://rennlist.com/forums/964-forum/19013-could-this-noise-be-pinging.html
https://rennlist.com/forums/964-forum/88016-warning-lights-suddenly-come-on.html
https://rennlist.com/forums/964-forum/124200-pinging.html

Colin 90 C2

If you jumper the 3 large slots in the relay base the car will be able to run without the relay. Be careful as the jumper wire will get very hot.

Colin

Fred, Long Island

I'll bet a Becks that your ECU is fried. Identical, I mean Identical symptoms to what I had two years ago. Check my posts under 'ghost'

springer3

Have you checked for water or other contamination in the fuel? Are the filters fresh and clean?

BGLeduc

While it seems that there can be more than one cause of this issue, this is a classic symptom of an issue with the airflow meter hareness. Porsche has a TSB on the subject, 9005, dated 4/16/90.

Not sure if this applies to later years (I would doubt it), as your is a '91.

The fix is to simply reroute the harness. I had the problem, and my wrench jumped through hoops trying to fix it until he found the TSB.

Good luck.

BGL

jonfkaminsky

Thanks so far for the ideas gentlemen. Filters are fresh- both air and fuel. However, interesting note on the airflow meter harness. I had removed the airbox while replacing sparkplugs (for better access) and perhaps I jarred something or shorted something. Doesn't explain why it ran great after the new sparks and wires, and started this business two weeks later, but its worth looking into. My car was built in July 1990 which is post the february 1990 build date for this defect.

I'll get the TSB nonetheless.

many thanks
Jon

BGLeduc

I really can't say. I just went to look and my subscription seems to have lapsed. Crap!

I may have given you some bad info. I have hard copy of the TSB, and it says it replaces 9005, but I do not see the current number. It does say that the protective cover on the harness (the source of the problem) was discontinued on 2/13/90, so it would apepar that you were not effected.

If you want, I can FAX you the hard copy. The only problem will be that the disgrams will be very hard to read. If you want drop me an emial with a fax # to bleduc@comcast.net.

BGL

deep_purple

Hi,

Here's some more info. It is a small probability, but maybe the harness is problematic...

My story with hesitation/stalling

Good luck,
ST

cjaz

i had a similar situation, it was the hall sender. it was difficult to keep it started and would buck and run extremely rough. i only drove mine about 1/4 of a mile before having it towed.

DaveK

I've had "bucking" twice. Once it was the flywheel position sensor - the car bucked for about 5 miles, then when I pulled over it died and wouldn't start (turned out the flywheel sensor had fallen out!). The other time - seemed to be cured by new coils and cleaning the air flow meter. However, a few weeks later I had stalling problems - changed the air flow meter and it has been fine since (a couple of weeks).

Even if it's not the harness, it could be the tracks on the sensor. Have you tried cleaning them up?

DaveK

Yes.

You can open it up (take the black plastic lid off it) by carefully cutting around it - it's only held on with clear silicon, and you can seal it back up afterwards. Then you can clean the contacts. That didn't help with mine though, because it was only a few weeks later that I swapped the part - I didn't expect it to make a difference (since I'd cleaned mine properly) but it did.

When I did clean mine up, I could see that there seemed to be small gaps in the tracking. I hoped it would be OK because there seem to be multiple tracks so I figured there was kind of a backup track - but I guess not.

If you could get hold of a spare one to try out, it would be worth it - you could then rule that out as a problem.

jonfkaminsky

Could be the coils as well. When I replaced the spark plugs, I did notice a great deal of corrosion on top of one of the coils. I just cleaned it up. The coils are about two years old.

darth

Jon

I bet it's your coil. If you take the covers off the coils and start the engine in the dark you'll probably see a lightning storm around them. Those high voltage sparks finding their way to ground have a nasty habit of playing havoc on your sensitive low voltage electronics like the hall sensors. Before I replaced my wires my dash lights were lighting up from time to time and the hammer always reported a bad hall sensor.
Also check that the spark plug wires haven't come loose from the spark plug this could be another source of the spark finding its' way to ground and creating an arc.

Hope this helps
Bill
90C2

garrett376

As Bill said - since you did replace those wires, you may have one loose or not seated completely. It takes a decent amount of force to get them to snap in - especially on the distributor cap itself. That would certainly be a source for a lot of electrical interference.

Especially since you ran fine for a while - and now it's broken again - that makes it very possible that a plug wire wiggled loose in the past couple weeks. Go check those!!! Then let us know how it goes!

darth

The coils I believe are quite inexpensive and yes a coil is a coil is a coil - the difference being some are better quality, more windings, the way they mount , connections etc.. You can repair a coil that's been tracking (i.e. sparking) by sanding then polishing the top where the arc tracks are happening. The smoother you polish it after sanding out the carbon tracks the better - and the longer the repair will last. Dielectric grease also helps to keep moisture out and arcing from reoccuring. I think Vertex sells them inexpensively if you want new.

Hope this helps
Bill
90C2