Will adjusting TPS change IAC sensor?
Thread Starter
Drifting
Joined: Dec 2012
Posts: 1,504
Likes: 73
From: Georgetown TX
Will adjusting TPS change IAC sensor?
I’m getting ready to adjust my minimum idle adjustment using a different method then I normally use. This time I am going to try the method of adjusting my AIC to read around 20 steps at idle and then adjust TPIS to .54 volts at idle. My question is once I set my .54 volts on TPIS, will this Change my IAC to some other value? Will I then have to re-adjust back and forth trying to get as close to 20 steps and .54 volts as I can, or do I just make the adjustments the first time and leave it.
Le Mans Master
Joined: Aug 2017
Posts: 6,944
Likes: 1,490
From: New Jersey
I am not 100% sure but it may only until it gets a drive cycle. Adjusting the TPS will make it think the throttle position has changed but once it does a relearn it should go back I would think?
Le Mans Master
Joined: Sep 2013
Posts: 6,192
Likes: 750
From: near the thumb in the mitten
It can of TPS value gets too high. Earlier throttle body TPS is adjustable. So minimum air rate or idle is set then TPS value is set. The later throttle body with non adjustable TPS the value is more of a range. If the minimum air rate or IAC counts depending how you're doing it has TPS value too high; you will need to look for cause. Retarded timing for example could require more throttle opening to reach correct idle speed.
Aftermarket Throttle Body gets tricky and may require tuning as the added air isn't calculated in fuel map.
Aftermarket Throttle Body gets tricky and may require tuning as the added air isn't calculated in fuel map.
Melting Slicks
Joined: Aug 2003
Posts: 3,409
Likes: 400
From: Lakeville MI
Remember to check both in gear and in park/neutral if auto trans and choose the minimum of the 2 conditions and set accordingly.
This is also best done at the lowest ambient temperature that the car will operate in, or the idle will likely hang high at low temperature with zero IAC counts. Or just plan on re-adjusting all the time for changing conditions.
Also you want the car to be capable of idling at 6° advance so that you can set the timing in the future, so you may want to unplug the est connector while setting min air in order to be sure it will still run.
This is also best done at the lowest ambient temperature that the car will operate in, or the idle will likely hang high at low temperature with zero IAC counts. Or just plan on re-adjusting all the time for changing conditions.
Also you want the car to be capable of idling at 6° advance so that you can set the timing in the future, so you may want to unplug the est connector while setting min air in order to be sure it will still run.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
TPS measure RATE of change, for "accel pump shot". I've never seen the TPS affect IAC other than while there is TPS movement and for a few seconds after that. In my observations, you can run the ups all the way up to "WOT"...once you're done moving to WOT, the engine resumes a normal idle.
IAC should be commanded by the ECM to achieve programmed idle speed regardless of TPS position.
Team Owner
Joined: Jul 2004
Posts: 28,499
Likes: 3,298
From: Hartford WI
Set the IAC to 20. When you change the TPS, the idle speed and IAC will change, because the ECM is responding to a change in TPS voltage since the last engine start, but set TPS to your desired value. Turn off the key, wait a few seconds and restart. The IAC should now be your 20. The ECM "relearns" closed throttle voltage at every key=on.
Team Owner
Joined: Jul 2004
Posts: 28,499
Likes: 3,298
From: Hartford WI
Remember to check both in gear and in park/neutral if auto trans and choose the minimum of the 2 conditions and set accordingly.
This is also best done at the lowest ambient temperature that the car will operate in, or the idle will likely hang high at low temperature with zero IAC counts. Or just plan on re-adjusting all the time for changing conditions.
Also you want the car to be capable of idling at 6° advance so that you can set the timing in the future, so you may want to unplug the est connector while setting min air in order to be sure it will still run.
This is also best done at the lowest ambient temperature that the car will operate in, or the idle will likely hang high at low temperature with zero IAC counts. Or just plan on re-adjusting all the time for changing conditions.
Also you want the car to be capable of idling at 6° advance so that you can set the timing in the future, so you may want to unplug the est connector while setting min air in order to be sure it will still run.
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