stumbling issues
 

ok I'm tired of throwing parts at this car hoping that it would help, i'm a poor college kid and one can only keep up the money pit gig for so long...so I'm seeking the advice of you guys who are more well versed with porsche then myself. It's an 87 944 N/A, stock besides a throttle cam.

the symptoms:

engine RPM drop and bog immediately after startup, has gotten progressively worse in the past few weeks
engine RPM drop and bog after the idle contacts of the TPS are open then immediately closed again without any additional throttle
engine RPM drop and bog after any letting off throttle when not engaged in a gear
stumbling under acceleration, gets progressively worse with load. When I put it in 4th or 5th gear, at about 2700 it starts to randomly stumble and miss pretty bad
no power whatsoever, acceleration in the mid-high end of first feels like I'm accelerating in the low end of 2nd
no large changes in fuel consumption, I get 85-100 miles to each 1/4 tank
I pulled a spark plug, looks a little lean to me, it's burning a bit of oil so the base is black. The insulator has a brown spot on the side of it reacing up to the electrode, and the ground is off-white from the tip down to the base where you can tell oil has been burning.


what's been replaced in the last few thousand miles:

Plugs, wires, cap, rotor (iridium NGK plugs, and no gap issues)
fuel/air filter
AFM (used, but tested good junkyard one)
accordian hose (intake hose)
DME temperature sensor

I've also run a few things of injector cleaner through it. I'm hoping it's the fuel pressure regulator or something since it's only $50 (i'd test it, but I don't have the tools right now), but whatever it is I want to get it fixed.

RE: stumbling issues
 

one more addition that i JUST discovered. There's a leak in the line coming off the dampner. It idled fine, until i saw a bit of residue on the top and played with the line, fuel came out and things started going south. I'll try fixing that and report my findings.

RE: stumbling issues
 

The fuel line that is leaking was a recalled hose, which is good indefinitely. Call your porsche dealer and see if the recall has been done to your vehicle. If not, that should be done for free.

Try unplugging your TPS and see how the car behaves with it unplugged.

RE: stumbling issues
 

oh sweetness, free service! I'll be calling them tomorrow about it.


One question though, is the TPS a potentiometer type, or is it simply closed/open/closed on the idle and wide open points? I'll try unplugging it, but if it's simply a switch type and it tested ok on the ohmmeter, shouldn't the problem lie elsewhere?

RE: stumbling issues
 

after giving porsche a call, they say that my car has already been serviced under the recall...maybe she got the wrong VIN number or something, because after looking over the records of the anal-retentive previous owners, I can't find anything. The hose is $140 from pelican parts, and takes a week and a half to get here.

does anybody know the thread size of the pressure dampner? I want to make a temporary fix so that I don't have to worry about my car turning into an inferno...if I can find a hose specialty shop with the correct fittings, I may even be able to make a permanent fix.