altarchsa

I was too quick to report that the MAF wiring harness revision solved my problems, as described in my "Surges and Dies" thread. It ran great for the better part of a day, but the gremlin is back. Here's the original post:


The car starts good and runs great when cold and at higher rpm's. However, after warming up a few minutes it develops a strong surging when at idle or low rpm. It then starts missing and dies. If I keep the rpm's up (2000+), I don't have a problem. If not it surges and misses, and if rpm's let to fall low enough, it dies. When I crank to restart, it doesn't even try to start for some time (varies). I've noticed a cloud of white "smoke" from the exhaust after a few seconds of cranking, looks and smells like gas vapor from the unburned fuel being pumped through the hot exhaust system. When it finally tries to start, I've noticed depressing the accelerator slowly seems to let it eventually catch hold, then it races off like nothing ever happened. If I catch it when it first begins missing, I can usually race the engine and get it to stop missing and run properly at the higher rpm's.

At first I thought it was losing spark, but then thought it might actually be flooding out.

ISV and MAPF were recently cleaned. Fuel relay and coils replaced.



Any other ideas? Anyone????

Sire

Question did you order the piggyback allso?

james944

I'm new here myself so I don't know much about these cars, but since you're asking for ideas...

Could you have a vacuum leak that somehow opens up when the car is warm?

My 944 split a hose producing a big vacuum leak and the symptoms were similar: It would not start well and the engine would die if left to idle, but if I kept the revs up it would drive o.k..

If you've worked on the ISV maybe some vacuum hoses were disturbed? Just a thought if you've run out of other easy things to check.


Experts, does this suggestion make any sense?

choogh

I had similar problems and, there on the way back again, after almost a year without...This is what worked for me.
I removed the air cleaner. complete with the vacuum canister and electrical connector.
Cleaned the intake temp sensor with a clean cloth (actually, it was a "soft wipe")
Put my arm inside the intake barrel so I could reach the air flow senor vane and, with the soft wipe, cleaned all around the vane and housing, to be fair, not a lot of dirt or, oil was evident, but the wipe was "soiled"..
Re-assembled, cleaning the electrical contacts, cleaned and replaced the air filter..and gave her a go... ran like a dream for about 9 months or so, now it's starting to "hunt, stall etc". I think it's because I slightly "over filled" on the oil when topping up...the oil reservior vents into the air intake and, I think leaves a deposit on the sensor and vane "gumming" up the works !!!.
Give it a try, it's about 30 minutes work, with no costs involved.(nick the wipes from the wife !!)

mada1

Just because the ISV was cleaned recently doesn't mean that it is working. I had similar problems that continued after many an ISV cleaning.
I finally bought a new ISV no problems since.
Those things do have a life span.

At least try to see if you can at least borrow one somewhere and try it.
good luck.

altarchsa

Thanks guys.

I had cleaned the MAF by completely removing it. Same thing with ISV. But the MAF may have gotten some oil in it because I did overfill the oil recently. I'll re-clean it. Also, will go for th eISV if that doesn't work.

Thanks.

altarchsa

Sire, Don't know what you mean by piggyback. Please explain.

James, I'm pretty sure it's not a vacuum leak because it is intermittent, even when warm. The ISV makes most sense because it sounds like it could "go in and out" if it is going bad.

Indycam

"Sire, Don't know what you mean by piggyback. Please explain."
Google "piggyback chip" .

Sire

John from Vitesse sels the MAF with piggyback, then you are able to connect your computer at a laptop and manage all kinds off stuf by youreself.

Richard Curtis

Clean all the electrical grounds, especially between negative battery cable and the unibody; also clean the battery terminal connections. If that doesn't work, try installing a new DME relay (you should carry a spare one anyhow). If that doesn't work, see if you can get a code.

altarchsa

Recent battery, so connections at battery are good. I'll check at cable to chassis.

Changed DME relay first thing (second new one in a few months). No change in performance.