Typical IAC count Cammed Z28
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Registered User
Joined: Jan 2002
Posts: 302
From: Rapid City, SD, USA
Typical IAC count Cammed Z28
I've got a CC306 in my Z28. After setting idle to around 1k RPM while in drive with car warmed up the IAC count is maxed out at 160. I tinkered around with the Idle screw on the throttle body to try and get it down. Unfortunately all that did was make the engine rev up to around 1.5k rpm w/ no change in IAC count.
I'm trying to determine if my IAC is toast. Could some people tell me if these numbers sound in order? Once moving from park (900rpm idle speed) to drive the engine drops to about 600rpm and slowly moves up to the 1k rpm drive idle speed.
Thanks for the help!
I'm trying to determine if my IAC is toast. Could some people tell me if these numbers sound in order? Once moving from park (900rpm idle speed) to drive the engine drops to about 600rpm and slowly moves up to the 1k rpm drive idle speed.
Thanks for the help!
Registered User
Joined: Dec 2000
Posts: 766
From: GARDNERS,PA
Re: Typical IAC count Cammed Z28
I try to run my CC306 car between 60 and 90 counts when warmed up. Close the throttle blades to increase counts, open the blades to decrease counts. I adjust my screw while scanning until I hit the window. If this does not work then your IAC may be toast.
Steve
Steve
Registered User
Joined: Dec 2000
Posts: 766
From: GARDNERS,PA
Re: Typical IAC count Cammed Z28
Yep,
You'll definately need to rescale the MAF table. With the stock tables, the PCM will pull fuel like crazy at the lower RPM's and Air Flows. At the higher RPM and AFGS the PCM will add fuel due to better volumetric efficiency. Work to get the MAF tables in good order.
Probably have to bump up idle speed table a bit.
Adding about 4 degrees of closed throttle timing in and around the idle range seems to help clean up idle a little
You may have to pull some timing out of the main table in the cruise range to prevent surging.
Oh Yea,
Make sure you have ZERO exhaust leaks upstream from the O2's or all your tuning will be wasted.
You'll definately need to rescale the MAF table. With the stock tables, the PCM will pull fuel like crazy at the lower RPM's and Air Flows. At the higher RPM and AFGS the PCM will add fuel due to better volumetric efficiency. Work to get the MAF tables in good order.
Probably have to bump up idle speed table a bit.
Adding about 4 degrees of closed throttle timing in and around the idle range seems to help clean up idle a little
You may have to pull some timing out of the main table in the cruise range to prevent surging.
Oh Yea,
Make sure you have ZERO exhaust leaks upstream from the O2's or all your tuning will be wasted.
Thread Starter
Registered User
Joined: Jan 2002
Posts: 302
From: Rapid City, SD, USA
Re: Typical IAC count Cammed Z28
Originally Posted by SABLT194
Yep,
You'll definately need to rescale the MAF table. With the stock tables, the PCM will pull fuel like crazy at the lower RPM's and Air Flows. At the higher RPM and AFGS the PCM will add fuel due to better volumetric efficiency. Work to get the MAF tables in good order.
Probably have to bump up idle speed table a bit.
Adding about 4 degrees of closed throttle timing in and around the idle range seems to help clean up idle a little
You may have to pull some timing out of the main table in the cruise range to prevent surging.
Oh Yea,
Make sure you have ZERO exhaust leaks upstream from the O2's or all your tuning will be wasted.
You'll definately need to rescale the MAF table. With the stock tables, the PCM will pull fuel like crazy at the lower RPM's and Air Flows. At the higher RPM and AFGS the PCM will add fuel due to better volumetric efficiency. Work to get the MAF tables in good order.
Probably have to bump up idle speed table a bit.
Adding about 4 degrees of closed throttle timing in and around the idle range seems to help clean up idle a little
You may have to pull some timing out of the main table in the cruise range to prevent surging.
Oh Yea,
Make sure you have ZERO exhaust leaks upstream from the O2's or all your tuning will be wasted.
Thread Starter
Registered User
Joined: Jan 2002
Posts: 302
From: Rapid City, SD, USA
Re: Typical IAC count Cammed Z28
I got myself some new 1.6:1 roller rockers and started back into tuning the IAC. I can get the counts within good range. However, when I start the car it revs up to about 1500 rpm then slowly drops down to 1k rpm (new idle i set the car at)... how do I fix it so it doesn't do that?
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