0 iac reading?
0 iac reading? im having problems getting my car to idle i sticks at around 2000 and at times drops my tps was broke so i replaced it did a tps reset and my iac keeps reading 0 so i replaced that after trying to set the tb screw like a million times the iac starts at 135 and drops fast down to 0 when i start it when i give it gas the iac goes up but my rpms are at 3500 to get 60 on the iac any one have anyclue what else could be wrong
TECH Fanatic
Joined: Feb 2004
Posts: 1,259
Likes: 0
From: Lexington, KY
Usually that just means the actual airflow is above desired airflow at idle because either the hole in the tb blade is too big or the adjustment screw is adjusted to high. With the motor fully warmed up, the fans NOT running and AC off, back off the idle adjust screw until IAC counts are 50 - 60 at idle. It may be reading higher when you first start it for a variety of reasons but should be adjusted only when the motor is warmed up and nothing else is influencing the IAC valve such as the fans or AC. Also, if you change timing at idle it will change your IAC counts as well.
Trending Topics
IAC is only "push", the "reading" is whatever the
PCM thinks it wants. It wants no more, probably
less, than it's getting.
If your TB stop-screw is really jacking the blade
then you may not even be idling as far as the PCM
is concerned. There is a max TPS position for idle
routines (such as adaptive airflow and spark) to
be active.
The PCM has probably had some bad learning and
will have to unlearn if you un-jack the blade. It
may work out for you to do this a bit at a time,
so it doesn't get all confused and go sulk.
A whack VE table low end can result in the PCM
thinking it has way more air than it does, fuel it
accordingly, then see a pig rich mixture that wants
even more air than it should. Also making unstable
the RPM control loop, if you should happen to be
in closed loop idle operation, for constant crash.
PCM thinks it wants. It wants no more, probably
less, than it's getting.
If your TB stop-screw is really jacking the blade
then you may not even be idling as far as the PCM
is concerned. There is a max TPS position for idle
routines (such as adaptive airflow and spark) to
be active.
The PCM has probably had some bad learning and
will have to unlearn if you un-jack the blade. It
may work out for you to do this a bit at a time,
so it doesn't get all confused and go sulk.
A whack VE table low end can result in the PCM
thinking it has way more air than it does, fuel it
accordingly, then see a pig rich mixture that wants
even more air than it should. Also making unstable
the RPM control loop, if you should happen to be
in closed loop idle operation, for constant crash.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
that sounds like how mine behaves sometimes...it will sit and idle for a minute or so then the rpms drop to nearly nothing and it revs itself up to above 1k rpm then it dips back and forth until it finally catches and will idle again
also does this when going from drive to park or neutral a lot of the time but not always
also does this when going from drive to park or neutral a lot of the time but not always
Idle Air Control.
To the OP, I agree with the others, You're getting too much airflow so the IAC will not want any counts. It's shut as far as it can go in an attempt to get the airflow down. You're getting your air from somewhere else, which is what's raising your idle. Check the adjustment screw on the TB and make sure that your TB blade is closing as it should to put the motor at idle.
To the OP, I agree with the others, You're getting too much airflow so the IAC will not want any counts. It's shut as far as it can go in an attempt to get the airflow down. You're getting your air from somewhere else, which is what's raising your idle. Check the adjustment screw on the TB and make sure that your TB blade is closing as it should to put the motor at idle.
