Whitesands

How many revs is the normal when stating from cold? My 88 S4 Auto jumps to 2000 and slowly starts dropping, after 3 minutes its still at 1000, when fully warm its steady at 700, it makes for a big jolt when selecting a gear
What should I be checking?

worf928

Temp-II sensor
Idle Stabilizer Valve
Intake Leaks (when the engine's cold)
Vacuum leaks
Idle reduction for engaging tranny
Mass-Air Sensor

The LH/EZK troubleshooting guide on Jim's CDs has step-by-step procedures for checking these (although checking for intake leaks is more art than science.)

rmr25

When my engine did much as you described, I found the source to be a faulty wire between the throttle position switch and the EZK brain idle control. It took a lot to trace this down, including removing the intake. While I was in there I checked/replaced the usual suspects: ISV, hoses, connections, etc.. The engine now starts from cold and idles at precisely 650 rpms. During troubleshooting I got a lot of help from John Speake, Bill Ball and others here on this Forum.

Brett Matthews

My '87 does somewhat the same, except the jump is only up to about 1400 R's, and it fairly quickly falls off to about 900 R's. When fully warm, the tach sits at @ 750R's.... And this has been going on since the full under intake redo.

Whitesands

Thanks all,

Seems it was the first item on your list Dave....Temp-II sensor or I should say corrosion the terminals/connecters, now starts and idles ok.

worf928

Good for you!

Giovanni

Hmm, not sure how I missed your post Ivan. When I had the car I had to pull the pedal a bit when starting the car. It quit doing that for a while but I guess it resurfaced again. After you start it again (when warm) it starts and idles fine. I guess its a weak throttle linkage?

Bill Ball

This points to a vacuum leak. The vacuum modulator on the tranny not getting vacuum would account for the jolt.