My 944 studders when "cold".

[andytheturtle]

Update #3: no it was/is not.

Update #2: it was/is the TPS.

Update: it is now dead, I am almost sure it is the DME.

For about 3 weeks now, when I start my 944 after leving it over night it studders and has very bad throttle response, once warmed up it runs fine for the rest of the day. my Dad is a former VW, Ford and BMW mechanic (different dealerships) told me to add carbon cleaner to the fuel, nothing, add injector cleaner, nothing, and finally replace the air filter, zero difference. it is not a cracked head gasket (nothing in the oil) I think it is a vaccum leak, but what else could it be.

P.S. Yes I searched the forum before posting but want to cheak my preticular case.

[thekidd]

Mine does this too. Havent driven mine yet, INsoection troubles, but it stops the studdering at about half way through the first box on the temp. guage. Thanks for posting this, Ill keep a good eye on this.
Maybee a bad fuel pump, filter, injectors clogged, spark plugs bad?? Idk. I trouble starting my car before i changed my plugs. Before when I started it, it would crank a few times for about 3-5 seconds, start up and run fine. Witht the new plugs, she starts right up.

[aj951]

Check your DME temperature sensor. This sensor monitors your engine temperature and the DME adjusts the fuel/air mixture accordingly. If the sensor or connections to the sensor are bad, it fools the DME into giving the wrong mixture. Search on DME temperature sensor and check out Clark's Garage on how to troubleshoot.

A.J.

[jmd_forest]

Had the exact same or very similar problem. Turned out to be the TPS "idle switch" wasn't closing because the PO had adjusted the idle using the throttle cable. I adjusted the throttle cable to allow the TPS switch to close and all was better. Even if the throttle cable hasn't been jacked with, the TPS could still be bad or mis adjusted. clarks-garage.com has a test procedure using a DVM (I also used 2 wire pigtails to make the switch easier to reach) I also replaced several vacuum hoses (ISV, oil seperator, and venturi) a few weeks later and it runs much better now.

jmd_forest

[corby]

Did you ever find out what was wrong? my car has the same problem.

[andytheturtle]

Update: NO, it is still broke.

Yes, it was/is the TPS.
http://www.clarks-garage.com/pdf-manual/fuel-06.pdf

[andytheturtle]

Update. I replaced the TPS and it is still shuttering. what else could it be?

[Techno Duck]

Have you checked fuel pressure yet? Shuddering after sitting over night, could be leaking injector.. takes a minute for the fuel to burn off in the cylinder and your car will run rough during that period. It sounds weird but take a whiff of your dip stick to see if it smells like gasoline, not a tell tale sign but it does happen. Other issues could be a shot fuel pressure regulator. Check your fuel pressure before replacing anything though.