Old Soldier

Wife drives p-car to school at night. She drives about 20 miles part stop and go plus freeway. It's over 100 degrees outside. Car starts surgging just before she gets to school. Does not quit running but runs rough. Same thing on way home she makes it almost all the way. Ive changed fuel pump, fuel filter, damper and relay valve and all injecters. Any ideas my wife wants to just drop it off at the repair shop and tell them to fix it! All I can see is $$$$ signs.

Peckster

Gotta be cheaper to get an expert diagnosis. Are the injectors new? I'd wonder about vapor lock, but I don't think that can happen while the car's running.

SoCal Driver

You didn't change the fuel pressure regulator?

Old Soldier

Yes I changed the regulator also. The reason I'm concerned about taking it to the shop is that when I got it back last month after having the timing belts done was that they said I had a head gasket leak. (They told me this after all the work was done) and my head gasket seems fine. No water in oil, over heating or white smoke and I'm not loosing water.

SoCal Driver

Does not do this when the outside temp is mild or cold.

Posibilities:

Electrical connections. At the battery and from the battery to the ground on the firewall and at the engine. Have the battery and alternator tested.

DME temp sender in block. The one closest to the radiator. Has a plug on it much like the injector connectors.

Air flow sensor air temp sender.

emilysgranny

Check alt output and bat connectios and grounds as socal said. Suspect alt or bat is bad or the conection which is draining bat to the point it can't sustain ignition.

KLR

I think that you have largely ruled out a fuel issue at this point. Is there a reason why you originally assumed that it was fuel and not spark related? In any case, I third the suggestion that the temperature relationship suggests the usual electrical issues: dirty grounds, bad connection, and/or bad sensor somewhere.

Old Soldier

Thank you guys for answering my questions. I'm planning on turning it over to the garage tomorrow. As I had stated before the garage told me last month that I had a bad head gasket. The mechcanic tried to explain this to me but I didn't believe him because it didn't make any sense as related to my own experiance with chevies over the past 50 years. Could I be wrong? I still can't see any thing with my car to direct me towards a head gasket leak. Are these Porsche's different in some way?

kyle robert moore

where are you located? is there another porsche specialist in your area?


kyle

Manning

When does it run rough? Highway speeds? In stop and go? I had a similar heat related problem that I had assumed was because of the bogus alternator I was using. Never happened in cooler/cold weather but always when it is hot out while sitting in traffic. Know what it was? Vacuum leak. Mike1982 and I just replaced all of my vac hoses and the problem went away. The one that I know was leaky was the one on top of the oil mist separator. Can't get to it easily without pulling the manifold off, so while I was in there I replace all of them, and the O-rings on the separator.