- Hex wrench.
- Exhaust gaz analyser.
1. With the engine off: check the throttle body butterfly gap.
It have 0.002" gap with a feeler gauge at the bottom of the
butterfly. Stick a 0.002" gauge in the open throttle plate,
let the plate close with the gauge down at the bottom and see how
much drag you get removing it. Set the gap with the throttle stop
2. Warm up the car then shut it off.
3. Disconnect the O2 sensor at the connection. (round black connector).
4. Restart the car and before the catalytic converter gets hot (which
it won't with the car just idling) insert the gas analyser in the
5. Adjust the AFF screw the the allowable tolerances, from 0.2 to
1.2. Bill's car is setup to 0.9 to 1.0 and it seems to give a better
idle. It also helps get ride of a slight hesitation when accelerating.
The AFM can be turned over to locate the screw then you can turn
it back a little bit. (If you turn it completely, you won't be able
to insert the hex wrench).
The screw controls how much air bypasses the flapper on the afm.
By screwing it in, less air bypasses and it forces the flapper to
move further sending a different signal to the dme. Turn the screw
in to richen the mixture and out to lean it..
If you plan on doing it without a gaz analyser:
Gradually turn the adjusting screw in very small increments and
wait about 30 seconds after wach adjustment to see what it does
to the idle. Don't adjust it more than one
turn in either direction.