High idling when in neutral fully warmed up

[Mercedez]

I have had the IAC cleaned, PCV replaced, ACT sensor replaced, water coolant temp sensor replaced. Problem is intermittent but usually happens after driving 20 miles and might be connected to weather changes.

Any ideas how to solve this?

 

[HISSIN50]

If you shut the car off and restart it, does it idle normally again for a little bit?

 

[Mercedez]

If you shut the car off and restart it, does it idle normally again for a little bit?

No it doesn't.

 

[hotcobra03]

What does it do ?go to 1200rpms and stick or up down up down or stay low stay good?

 

[HISSIN50]

And to be very clear, this happens with the car totally stopped? Otherwise, the rolling-idle strategy keeps the RPMs at about 1200-1400.

 

[Mercedez]

And to be very clear, this happens with the car totally stopped? Otherwise, the rolling-idle strategy keeps the RPMs at about 1200-1400.

No once the idle is up it stays that way whether in neutral at a stop or moving on the freeway.

 

[drpgtcoupe]

could be ur temp sending unit. could be telling it its cold so its giving it more fuel. which usually means difficulty starting when its cold. throtal positioning sensore too. also could be ur maf sensor (mass air flow) or ur map(mass air pressure) sensore depending on the year or set up on the car.

 

[hotcobra03]

Question 2.. When idle goes high is it a steady high or a rolling idle. From cell phone i cant your info about ur car?

 

[2000xp8]

I'd check the tps.

 

[Mercedez]

Question 2.. When idle goes high is it a steady high or a rolling idle. From cell phone i cant your info about ur car?

It is a steady idle about 1,400 rpms.

 

[Mercedez]

could be ur temp sending unit. could be telling it its cold so its giving it more fuel. which usually means difficulty starting when its cold. throtal positioning sensore too. also could be ur maf sensor (mass air flow) or ur map(mass air pressure) sensore depending on the year or set up on the car.

Do you have a picture of what this sending unit looks like? the MAF was already replaced. It's factory set up.

 

[hotcobra03]

Question 3 is engine lite on or was on ,checked and cleared.and any codes to work with or lite is on/off and you are just changing parts as most do?

 

[HISSIN50]

The water temp sender had no connection to the EEC. It's only for the gauge. Otherwise, mention of the temp sensor was noted (one would assume this is the ECT) in the opening post. The ECT is a sensor and the gauge uses a sender.

 

[backfocus]

+1

I would check codes. An if you haven't done so check the useful tech treads, it is a sticky at the top of this forum. There is a Surging Idle check list that I would go through as many of the same things can cause a high idle. Or here is a direct link to it.

http://forums.stangnet.com/698148-help-me-create-surging-idle-checklist.html

 

[Mercedez]

+1

I would check codes. An if you haven't done so check the useful tech treads, it is a sticky at the top of this forum. There is a Surging Idle check list that I would go through as many of the same things can cause a high idle. Or here is a direct link to it.

http://forums.stangnet.com/698148-help-me-create-surging-idle-checklist.html

Thanks

 

[drpgtcoupe]

The coolant temperature sending unit (not "sensor") is on the driver side of the intake manifold, and it's screwed directly into the manifold. (The ECT sensor is screwed into the heater core feed pipe which is then screwed into the manifold.) It has a single-wire lead that is pushed onto the stud coming out of the top if the sending unit.

http://www.allfordmustangs.com/foru...temperature-sensor-act-my-new-car-015-act.jpg

this sensor tells the computer the motor is cold. therefore acting like a choke it gives the motor more fuel to warm up faster and run right when u dont let it warm up properly. just like a carburated motor with a choke. usually when they go out its a reverse effect when its saying its hot its cold and when its cold its hot. seen it thousand of time especially on 80 model chevy. not saying that ur problem but may be. usually cleaning wont help.

 

[Mercedez]

The coolant temperature sending unit (not "sensor") is on the driver side of the intake manifold, and it's screwed directly into the manifold. (The ECT sensor is screwed into the heater core feed pipe which is then screwed into the manifold.) It has a single-wire lead that is pushed onto the stud coming out of the top if the sending unit.

http://www.allfordmustangs.com/foru...temperature-sensor-act-my-new-car-015-act.jpg

this sensor tells the computer the motor is cold. therefore acting like a choke it gives the motor more fuel to warm up faster and run right when u dont let it warm up properly. just like a carburated motor with a choke. usually when they go out its a reverse effect when its saying its hot its cold and when its cold its hot. seen it thousand of time especially on 80 model chevy. not saying that ur problem but may be. usually cleaning wont help.

The coolant temp sending unit as described was replaced along with the ECT sensor both new parts but still getting this problem. It seems to appear when weather changes.

 

[drpgtcoupe]

after the car has sat over night, and the motor is cold is it hard to start in the morning? like does it turn over a few times befor it fires off or is it pretty short? and do u have to give it gas to keep it running till it is warm?

 

[drpgtcoupe]

also just cause ur parts are new dont mean there good. a wiring problem or something could cause it to mess up making it bad.

 

[Mercedez]

after the car has sat over night, and the motor is cold is it hard to start in the morning? like does it turn over a few times befor it fires off or is it pretty short? and do u have to give it gas to keep it running till it is warm?

Car has no problems starting up and the idle problem happens after car is fully warmed up.