Idle Misfortune

[xtrm281gt]

Lately my car seems to have trouble when taken out of gear and the RPM tach falls. Whether it's at a traffic light or just sitting on my driveway it seems that my car will just constantly rev at about 1500 rpm's without me touching the gas at all. It seems fine and idles low when the engine is cold before it is put in gear but after then it won't drop past 1500. Should this be a problem I should be taking very seriously and if so what is wrong with my stang

All advice is greatly appreciated!

 

[BMan5150]

Could be a bad TPS. . .
Or a bad/dirty IAC valve (some guys clean this and have good results

How long have you had that BBK CAI on your car? Did you (can you) still use the stock air screen with this CAI? Might want to do a quick swap of your old intake and see if it straightens out the idle problem.

 

[GT2000JAY]

You might want to check your TPS voltage after the car is warm at idle - it can be done with a voltage/multimeter - at idle (throttle body closed - at rest) the center wire (I believe there are three vertical wires in the connector) should read .98-.99 volts - if the reading is high, the car will idle high and trip a dtc for TPS voltage too high/out of range.

It's a simple check and if the voltage is too high it can be corrected by loosening the TPS and rotating it - you may have to grind out the screw holes a bit to allow you to rotate it. Personally, my idle was off after changing the T/B, I checked the voltage and it read .88 volts, I adjusted the position of the TPS and it idles perfect.

There is also a diagnostic trouble code (dtc) for TPS voltage. Do a search on the web for Ford EEC-V trouble codes - you'll find a list.

Just an idea of where to start - simple check.

Jay