|This Is a write-up that will hopefully help Digi-Fart around the world
for 8valve Golfs and Jettas built from 1988 - 1992
Here was my problem:
My car's Idle would bounce anywhere from 400-1200 rpm. The car would eventually stall if I didnt babysit it.
My car would also Buck when I let off the gas and when i would coast.
A quick checklist of things i had checked while attempting to fix my bad idle/bucking
-a clean isv
-a good o2 sensor
-a good coolant temp sensor (CTS)
-no vaccum leaks
-good intake boot
-good fuel pumps
-good MAF sensor.
-good Idle screw O-ring
-proer ignition and cam timing.
-good ground wires to the ECU
The cure? -
There is a switch on the bottom of the throttle body , It looks exactly like the Full Throttle switch, but on the bottom side of the Throttle body
This switch is the Idle Switch, it gets pressed in at closed throttle and switches the ECU into its Idle circuit, (minimizes fuel flow etc.)
As time passes this switch gets moved a little and the linkage cant switch it on anymore so it now has to be adjusted
How do you know if this problem applies to you? a quick guess is to see if your car stalls when you unplug the CTS :
The more certain way to check this is :
1- by listening for the switch to click ( same noise that the full throttle switch makes except you should hear it click as soon as you open the throttle with your hand instead of WOT. ) the engine should be off for you to be able to hear it .
2- by unplugging the 2 wire harness on the throttle body , ignition on, hook up a continuity tester to the 2 prongs and there should
be continuity at closed throttle,
if its not clicking or theres no continuity:
there are 2 tiny TORX head T-20 screws that you need to loosen so you can adjust the switch to the point where it will be actuated when you let off the throttle.....