Question on idle adjustment for 97 Q45

[audiovisiony33]

After driving the car for sometimes on a warm day. When I'm stopped at the light with A/C running the RPM starts to increase by it self from 700 rpm to 900 rpm in drive and 1000 rpm in netural. Once the rpm locks in high in order for me to bring rpm back to defult range I have to restart the car again.Feels like there is some triggering to keep the rpm higher as the temperture gets warn after driven for a while. Just like rpm going up slight when the AC is turned on. It happens more frequent when the temperture is warm. Any one any advise ?

[maxnix]

Buy the gaskets and clean the IAC valve.

Don't adjust the throttle cables!

[Q45tech]

If the coolant goes above 195-199F the ecu starts the summer overheat protection mode and decreases ignition advance by 1 degree for every 5F of excess. Once it has taken out 3 degrees [ 210F] it starts increasing idle rpm [fan speeds] to try that as a cooling method. Once coolant reach 220F really weird things happen to try to get your attention.They should have built in a TAZER to punish driver!

Probably a weak cooling system caused by dirt in front of rad fins, bent fins, low coolant, air in system.

12 year old cooling systems are ripe for a total rebuild!!!!!!!!!!!!!!!!!

[duck3986]

Do you notice any drop in power/performance when the engine gets hot?

How many miles are on the engine and have the knock sensors been replaced?

Don

[audiovisiony33]

Do you notice any drop in power/performance when the engine gets hot?

How many miles are on the engine and have the knock sensors been replaced?

Don

Yes indeed, Feels like you have an invisible jet ski trailer hitched behind me. Hey! Sounds like U know something about this. But temperture gauge on the dash is at normal range in the center no matter what. I owned the car since 55K and now is around 185K. I did KS, valve gasket, TB, new plugs, coolant & trans flush (always dealer), whole 9yds.

When the temperature is cooler it idle below 750rpm in gear and after driven on the freeway for an hour or so come to stop waitting at the light, sudden RPM starts to go up by it self to 800 RPM while stopped in drive like I turn on the AC. Then only way for me to adjust that is to restart the car and everything goes down to normal until next light.

[audiovisiony33]

If the coolant goes above 195-199F the ecu starts the summer overheat protection mode and decreases ignition advance by 1 degree for every 5F of excess. Once it has taken out 3 degrees [ 210F] it starts increasing idle rpm [fan speeds] to try that as a cooling method. Once coolant reach 220F really weird things happen to try to get your attention.They should have built in a TAZER to punish driver!

Probably a weak cooling system caused by dirt in front of rad fins, bent fins, low coolant, air in system.

12 year old cooling systems are ripe for a total rebuild!!!!!!!!!!!!!!!!!

I was thinking about replacing the temperture sensor by the radiator but that sensor is only for the dash gauge.

Is there another temperature sensor that sends signal to ECU ?

[maxnix]

But temperture gauge on the dash is at normal range in the center no matter what.

The temperature gauge is very overdamped and not calibrated, so the information it gives you is always outdated and irrelevant except to confirm catastrophic failure.