CG77VETTE

No help needed after all, I found my answers in tech tips.

rick lambert

Here's the procedure..Insert a clip, or jump the A&B terminal in the ALDL...turn the key to the ON, but don't start...the fan will probably turn on..don't worry.Wait about 30 seconds, then disconnect the IAC. The 30 seconds will allow the pintle to fully extend giving the ECM a new base zero to calculate and adjust IAC counts. Turn the ignition off, IAC still disconnected, remove the jumper from A&B.Start the engine and let it warm up,it may be a little difficult to keep it running, but should idle nicely after it warms up...140* should be fine. Reconnect the IAC and drive it, it's supposed to reset it after 30-35 mile at 30/40 MPH.

Da Mail Man

.....any involvement of the est wire with this proceedure?....does not the tps need to be adjusted also?...i have read similar posts and 1 says to disconect the est while setting idle, another says not...etc?..

rick lambert

No need to worry about the EST while setting the IAC. It's always a good idea to check the TPS, it's simple and also one of our most important sensors, this is done with the engine off..key on.

CFI-EFI

There is no idle adjustment on these cars. The idle speed is burned into the chip. It appears you are confusing rick lambert's explanation of re-acclimating the IAC after servicing or replacement, with the minimum air adjustment procedure. Disconnecting the EST is only necessary for setting the timing, and for the minimum air adjustment for some, specified years, consult YOUR FSM. If the minimum air adjustment isn't changed, then the TPS adjustment isn't affected. However, as rick lambert says, "It's always a good idea to check the TPS".

RACE ON!!!

Steel Breeze

I haven't heard of this part of the procedure. Perhaps, that's part of the procedure I am neglecting... Thanks...

Da Mail Man

...i made a bad choice of words....(idle)....

Da Mail Man

........ ........i know, i gotcha'

CFI-EFI

OK. But the rest, after the first two sentences, still applys.

RACE ON!!!

CG77VETTE

Thanks for all the help guys. I guess the tech tip is a little misleading. The tip instructs you to extend the pintel using a jumper with the IAC connected then remove jumper disconnect IAC and set idle to 400 in drive after warm up. I couldn't get the idle below 1,000 with the IAC disconnected. I'm going to reset the IAC per Rick's method tomorrow and post my results. Thanks again

CFI-EFI

You are somewhat changing horses in midstream. The title to the thread is, "'86 L98 IAC Adjustment Help Please". Now you are talking about the minimum air adjustment, which has re-acclimation of the IAC ("IAC Adjustment") as the last steps. I haven't read the tech tip you referred to, but briefly:

1. Warm up the engine.
2. With engine off, key off, jump terminals "A" and "B" on your ALDL.
3. Switch the key to "On". So not start the engine.
4. After 30 seconds, key still "On" and the jumper still in place, unplug the wire connector from the IAC valve.
5. Turn the ignition to "Off" and remove the jumper wire on the ALDL.
6. Check YOUR FSM to see if your car should have the EST disconnected.
7. Start your engine and adjust the throttle stop screw, if necessary, to obtain the specified or desired (400-450 rpm) minimum air, engine speed. This is NOT the idle speed adjustment, but it IS the same operation as if it were.
8. Shut off the engine, and reconnect the IAC wiring connector.
9. Switch the key to "On", engine "Off", and adjust the TPS.
10. Re-acclimate the IAC as this whole thread has described. MY FSM simply says to drive the warmed up car at a speed of over 35 - 40 mph.

Your post, quoted above, had some of the operations out of sequence which would explain why you couldn't get the engine slowed enough down to make the adjustment. With the ignition on and the ALDL jumped, the IAC pintle extends and closes off the IAC passages. THEN you disconnect the IAC, with the pintle extended before you remove the jumper. Otherwise the pintle retracts, and the engine will have more than just the throttle blades as a source of air.

RACE ON!!!

redrose

dunno what anybody else is lookin at, but my 86 FSM, page 6E3-C2-11 sez

! IMPORTANT
Disconnect the distributor set-timing connector.

CFI-EFI

If the throttle arm doesn't touch the minimum air adjustment stop screw, one needs to check why the throttle is hung up. It won't idle down until throttle is nearly closed against the stop screw. If the IAC has been properly disconnected the engine speed will be the minimum air adjustment speed, regardless of the TPS setting.


Don't let the throttle plates fully close. They could stick in the throttle bores and that can be dangerous. The proper adjustment of the minimum air prevents that. The throttle plates don't move when the ignition is turned off. They will remain as adjusted for the minimum air with the engine running or not.


Imagine that!

RACE ON!!!

rick lambert

You are correct about disconnecting the EST for Minimum Idle speed adjustment.

CFI-EFI

And mine does not. That is why I said, "6. Check YOUR FSM to see if your car should have the EST disconnected.".

RACE ON!!!

rick lambert

You are 100% correct CFI-EFI, it's alway important to check the FSMs...year specific. Even the 86s have minor differences from the 87s, and I suppose the 85s do too, obviously the 84 CFI has major differences.

CFI-EFI

You got THAT right. According to the FSM, you have to synchronize (balance) the TBs, with a manometer, before you make the minimum air adjustment. Can I borrow your manometer?

RACE ON!!!