CyCloNe!

Hey guys I'm having a rough time with my 944 Turbo... When I turn the car on it idles really rough but tries to stay at the 800-900rpm range. It sound like its try to maintain but then it will drop in idle and cut off... The AFM is reading good, has a new DME temp sensor, new bosch fuel pump and bosch plugs.

I'm thinking it's the ISV but I'm not sure.

When I accelerate it usually does good, some times it will stumble some but not that bad. Any ideas?

Rogue_Ant

ISV is possibly bad. But first check the TPS - it can cause problems as well.

CyCloNe!

Ya if I drive it I have to push on the accelerator and keep the rmp higher like 1500rpm so it won't shut off

Rogue_Ant

TPS checking

User 52121

Clark's Garage has a procedure that shows you how to disable the ISV by jumping 2 pins on the diagnostic connector. Should tell you pretty quickly if it's the ISV intervening or not. I'd also make sure you hear the "click" when the throttle is closed at the TPS. Another thing to look for would be a vacuum leak.

Adonay

After you said that i am almost convinced its the ISV.
My car was like that however i had other issues as well such as car died every time i stopped after hard acceleration and every time i wanted to stop at a red light etc.

The TPS may also have issues have it checked.

CyCloNe!

Hey guys I tried the trick with the Jumper wire to disengage the ISV... I didn't have the car fully warmed up only a few minutes, I installed the jumper and the car stablized a lot but still had a mind surge.. it was putt putt putt putting, lol. Then I decided to remove the jumper wire and when I did that the car went stable and sounded normal.

So I'm guessing it is the ISV? All Agreed? Opposed?

CyCloNe!

Hey guys I ordered a new ISV and will probably order a new TPS on the safe side. But I have some new issues. I was tried the jumper trick for the ISV and it didn't work the car continued to surge and would even cut off. I tried driving the car and when it got to idle it would sometimes cut off and would have a hard time starting and finally once time it didn't start. I then let the car sit for an hour and it cut on. I'm kind of confused....

Tomorrow I'm taking of the intake manifold and looking at the ISV and the vacum lines... but I question whether the ISV is the problem now...

I'm wondering if its a reference sensor now

onspeed

fuel pressure regulator maybe?

CyCloNe!

Nope, just bought a new one 5 months ago and also had a fuel pressure test and it all checked out... I really feel its a sensor. It maybe the TPS or reference sensors, but I dunno... I swear this car drives me nuts, I fix it drive for a week and then I replace something again.

onspeed

Lol, welcome to owning a 21-25 year old car.

CyCloNe!

lol, tell that to my wife.

Hey guys has anyone ever decided to relocate the ISV? I was going to remove the intake manifold and then I found out I don't have a 6m Allen head only a 5,7,and8m, so I was going to try and remove it with the manifold installed. After looking at it I should be able to, the hard part is getting the ISV holding braket lose.

But I was thinking of installing a larger hose and relocating it so it's not has hard to remove next time.

ehall

CyCloNe, check your RW pm's. Also, you can easily check the TPS by just unplugging it.

onspeed

you wouldn't happen to have the tool set that came with the car? there's a nice long 6mm in there... but you'd have to get one to torque the intake back down.

and good luck getting that ISV out without removing the intake.

CyCloNe!

Well i checked the Reference sensors and they're still good....