That's right.
IAC counts
Melting Slicks
Joined: Aug 2003
Posts: 3,407
Likes: 400
From: Lakeville MI
160 counts is the maximum value for 89 and later cars.
What is your target rpm and actual rpm? If rpm is always low, the IAC will open to increase idle rpm.
Likely causes:
Not enough throttle opening
Retarded ignition timing
Plugged IAC
High tps voltage.
High desired idle rpm
Also could be an electrical problem with the IAC stepper motor, connector or wiring. With the IAC disconnected, the ECM will still try and control the idle and add counts as required even though there will be no effect.
Note: By the way, I like Sweden, I've been there many times (Arvidsjuar). Isn't it about time for a Pripps or Lapin Kulta maybe? I could go for a Swedish pizza myself. Skoll!
What is your target rpm and actual rpm? If rpm is always low, the IAC will open to increase idle rpm.
Likely causes:
Not enough throttle opening
Retarded ignition timing
Plugged IAC
High tps voltage.
High desired idle rpm
Also could be an electrical problem with the IAC stepper motor, connector or wiring. With the IAC disconnected, the ECM will still try and control the idle and add counts as required even though there will be no effect.
Note: By the way, I like Sweden, I've been there many times (Arvidsjuar). Isn't it about time for a Pripps or Lapin Kulta maybe? I could go for a Swedish pizza myself. Skoll!
Last edited by tequilaboy; Jan 5, 2007 at 11:24 AM.
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 3,010
Likes: 1
From: Sweden/Stockholm
160 counts is the maximum value for 89 and later cars.
What is your target rpm and actual rpm? If rpm is always low, the IAC will open to increase idle rpm.
Likely causes:
Not enough throttle opening
Retarded ignition timing
Plugged IAC
High tps voltage.
High desired idle rpm
Also could be an electrical problem with the IAC stepper motor, connector or wiring. With the IAC disconnected, the ECM will still try and control the idle and add counts as required even though there will be no effect.
Note: By the way, I like Sweden, I've been there many times (Arvidsjuar). Isn't it about time for a Pripps or Lapin Kulta maybe? I could go for a Swedish pizza myself. Skoll!
What is your target rpm and actual rpm? If rpm is always low, the IAC will open to increase idle rpm.
Likely causes:
Not enough throttle opening
Retarded ignition timing
Plugged IAC
High tps voltage.
High desired idle rpm
Also could be an electrical problem with the IAC stepper motor, connector or wiring. With the IAC disconnected, the ECM will still try and control the idle and add counts as required even though there will be no effect.
Note: By the way, I like Sweden, I've been there many times (Arvidsjuar). Isn't it about time for a Pripps or Lapin Kulta maybe? I could go for a Swedish pizza myself. Skoll!
I guess the ECM is not getting any info/feedback from the IAC motor, and thats why the counts is always 160? I know in the 8D bin the IAC "rest" count is 160.
I dunno..
Note: Arvidsjuar you say
That is a coold place in the winter. Im from Stockholm Yeah "pripps" would be nice And "skål" to you to m8 
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 3,010
Likes: 1
From: Sweden/Stockholm
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
You need to see if it's capable of working. Try to reset it first. Lightly depress the accelerator and start it. Let it run for 10 seconds; then off for 5 and then restart to see if it's right.
Ground the diagnostic terminal and with the key on, that should fully extend it. Disconnect it and when you start it, it should be at base idle - 425 to 450 rpms (you might want to get it to operating temp before you do this). If it works, reset per above.
Otherwise get out your test light and see if it flashes on each lead with the test light to ground and the diagnostic terminal grounded. Any leads that don't flash need to be inspected. Test should be repeated on any with a steady light with the ECM disconnected - that will rule out/confirm a short to voltage. Steady light or no flash, good wiring, replace the ECM.
Check resistance between A & B and C & D - should be 20 ohms.
If it all checks out, pintle is probably stuck - you can try cleaning or just replace it.
Ground the diagnostic terminal and with the key on, that should fully extend it. Disconnect it and when you start it, it should be at base idle - 425 to 450 rpms (you might want to get it to operating temp before you do this). If it works, reset per above.
Otherwise get out your test light and see if it flashes on each lead with the test light to ground and the diagnostic terminal grounded. Any leads that don't flash need to be inspected. Test should be repeated on any with a steady light with the ECM disconnected - that will rule out/confirm a short to voltage. Steady light or no flash, good wiring, replace the ECM.
Check resistance between A & B and C & D - should be 20 ohms.
If it all checks out, pintle is probably stuck - you can try cleaning or just replace it.
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 3,010
Likes: 1
From: Sweden/Stockholm
You need to see if it's capable of working. Try to reset it first. Lightly depress the accelerator and start it. Let it run for 10 seconds; then off for 5 and then restart to see if it's right.
Ground the diagnostic terminal and with the key on, that should fully extend it. Disconnect it and when you start it, it should be at base idle - 425 to 450 rpms (you might want to get it to operating temp before you do this). If it works, reset per above.
Otherwise get out your test light and see if it flashes on each lead with the test light to ground and the diagnostic terminal grounded. Any leads that don't flash need to be inspected. Test should be repeated on any with a steady light with the ECM disconnected - that will rule out/confirm a short to voltage. Steady light or no flash, good wiring, replace the ECM.
Check resistance between A & B and C & D - should be 20 ohms.
If it all checks out, pintle is probably stuck - you can try cleaning or just replace it.
Ground the diagnostic terminal and with the key on, that should fully extend it. Disconnect it and when you start it, it should be at base idle - 425 to 450 rpms (you might want to get it to operating temp before you do this). If it works, reset per above.
Otherwise get out your test light and see if it flashes on each lead with the test light to ground and the diagnostic terminal grounded. Any leads that don't flash need to be inspected. Test should be repeated on any with a steady light with the ECM disconnected - that will rule out/confirm a short to voltage. Steady light or no flash, good wiring, replace the ECM.
Check resistance between A & B and C & D - should be 20 ohms.
If it all checks out, pintle is probably stuck - you can try cleaning or just replace it.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
Melting Slicks
Joined: Aug 2003
Posts: 3,407
Likes: 400
From: Lakeville MI
Here are a few more simple tests you can perform:
With ign on and engine off, disconnect the IAC, it should be fully open (160 counts). Start car and note idle rpm. It should be rather high, 400-600 rpm above normal. Maybe 1200 rpm or so.
Turn off ign and reconnect IAC
Turn ign back on without starting engine, hold throttle open to WOT and unplug the IAC, it should be fully closed now. Start car and note idle rpm again.
It should be 500-600 rpm or so depending upon the min air adjustment.
If you see a significant rpm difference, the IAC is working properly.
Edited;
On second thought, I don't think this approach will work. Opening the throttle to WOT will not close the IAC. I don't know what I was thinking when I posted this.
You can get the IAC to fully close by grounding the ALDL.
With ign on and engine off, disconnect the IAC, it should be fully open (160 counts). Start car and note idle rpm. It should be rather high, 400-600 rpm above normal. Maybe 1200 rpm or so.
Turn off ign and reconnect IAC
Turn ign back on without starting engine, hold throttle open to WOT and unplug the IAC, it should be fully closed now. Start car and note idle rpm again.
It should be 500-600 rpm or so depending upon the min air adjustment.
If you see a significant rpm difference, the IAC is working properly.
Edited;
On second thought, I don't think this approach will work. Opening the throttle to WOT will not close the IAC. I don't know what I was thinking when I posted this.
You can get the IAC to fully close by grounding the ALDL.
Last edited by tequilaboy; Jan 7, 2007 at 03:13 PM.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
If you haven't fixed it, just send roundtrip tickets - I'll bring my scanner and spare IAC. (Note - Roundtrip Los Angeles to Heathrow is advertised at $350 US - Stockhom can't be much more right?).
- 1986 Original Owner -
Joined: Apr 1999
Posts: 3,193
Likes: 139
From: North Yorkshire, England
Cruise-In I Veteran
Cruise-In II Veteran
Cruise-In III Veteran
Cruise-In IV Veteran
Cruise-In VII Veteran
Damn Sun, Where'd you find that? I'm planning on a trip back for the CI and am looking for a cheap flight from Heathrow to Philly.
Thread Starter
Melting Slicks
Joined: Oct 2000
Posts: 3,010
Likes: 1
From: Sweden/Stockholm
But you are most welcome..
Last edited by devilfish; Jan 10, 2007 at 06:41 AM.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
"Damn Sun, Where'd you find that? I'm planning on a trip back for the CI and am looking for a cheap flight from Heathrow to Philly."
British Airways - over the Pole from LAX - they originally had it from San Diego, but they couldn't put on enough fuel (our runway is too damn short) so they went over to Phoenix to top off and then went non-stop from there. Could never get enough people to fly it - from the price, looks like they still can't. United and American supposedly are matching it. I might just fly over for a day two (at that price).
British Airways - over the Pole from LAX - they originally had it from San Diego, but they couldn't put on enough fuel (our runway is too damn short) so they went over to Phoenix to top off and then went non-stop from there. Could never get enough people to fly it - from the price, looks like they still can't. United and American supposedly are matching it. I might just fly over for a day two (at that price).
- 1986 Original Owner -
Joined: Apr 1999
Posts: 3,193
Likes: 139
From: North Yorkshire, England
Cruise-In I Veteran
Cruise-In II Veteran
Cruise-In III Veteran
Cruise-In IV Veteran
Cruise-In VII Veteran
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Ray - went to the British Airways site - they're quoting $199 each way now Monday through Wednesday from LAX. The kicker is a $158 tax (and damn I've got to drive to LA!). Still might be worth a quick jaunt, even if it is winter. Stockholm is a bit more.
