nxto

1991 S5 turbo

So my car was idling at 1500 for whatever reason, I adjusted the idle by turning the flathead screw counter clockwise for half a turn and it lowered it nicely. It also fixed the jerking problem my car has in 1st and 2nd gear. But after driving for a 10 minutes or so, it went back to it's old self...idling at 1500 and jerks like a **** in 1st and 2nd unless I'm EXTREMELY gentle with throttle...

Is this the problem with thermowax? Do I have to replace it now?

jjcobm

iTrader: (18)

did you ground the initial set coupler and made sure the car was FULLY warmed up before setting idle? If not, you did it wrong. After setting idle to 750rpm, set TPS to 1v.

nxto

no I didn't, I simply turned the flathead screw counter clockwise, what's the right procedure?

satch

iTrader: (1)

Look at pic #6 in the thread linked. There is an upside down screw that is part of the linkage. When the car is fully warmed up press down on this screw/linkage below the Thermowax piston and check to see if the idle drops or not. If it does then it is likely that your Thermowax/Fast Idle Cam is not working properly. You could pour some boiling water on top of the Thermowax when idling at 1500 and fully warmed up and see if the piston of the Thermowax extends more than it had been before the pouring of the water. If it does extend then either the coolant is not getting to the Thermowax properly. You could also tighten the screw which will help to lower the idle, but check the FSM for how it should properly work as the Fast Idle Cam should roll off the roll pin when working and set properly.