Idle confusion

[estutjaweh]

Strange one this...what would cause the idle speed to increase to 1300RPM when the engine has warmed up? When cold the idle speed is roughly 1100. Previously, when warm, it sat at 900ish. No idea whats going on but I checked the following:

CO2 = 1.8V
Fuel Pressure 3.0Bar
Throttle-pot = 34
Did an ECU reset

No change.

Could probably do with a stiffer throttle late spring as pushing this back per hand 'sometimes' helps...but surely this and/or cable couldn't affect the idle position ONLY when warm - or could it?

Engine is a 5.0l with red-top injectors, Adjustable Fuel Pressure valve, Tornado Chip, Large AFM, Twin Plenum, Induction pipes etc. Just received new plugs, leads, coolant sensor, Lamda sensors and have completely checked and resealed the plenum.

Any ideas?

Many thanks in advance.

[977]

Stepper motor.... ? Might not be able to shut as much as you need it to?

Other thing would be to check your speed sensor for the ECU is working. It only has 2 things it knows about "moving" and "not moving" if I remember correctly.

I'm sure some tunes held high idle while the car was moving so changing down was less brutal if you didn't heel and toe...