I'm Going Hunting

[Mulkers]

I have a hcr32 gtst typem

rb20det with cooler, exhaust, locker, teins and a hicas lock.

My car has begun hunting, and after running the diagnostic tool, (which showed little,) cleaning the afm, tps and aac valve, and resetting the ecu, i am beggining to become confused and i am after suggestions as to why this could occur.

Does anyone know a 'normal' voltage or resistance for the AAC Valve? (as i beleive this is the source of the problem).

Also, when the fan (ie ac) is turned on, the idle drops from 1900 (way too high, but high enough for it not to hunt,) to about 1100 rpm. This is what leads me to beleive that it is the AAC Valve.

I have adjusted the idle, both at the AAC valve and the ecu, and it still idles way too high/ hunts.

Short of replacing all involved components (and my life savings at a local nissan dealership) what other suggestions do you have?

BTW, I have already searched, and the most common problems (TPS, AFM, AAC Valve etc) were dealt with

Edited October 25, 2006 by Mulkers

[Mulkers]

So no one knows what could be going on?

[BHDave]

unplug the aac valve and see if the idle stabilizes. If it stalls adjust the idle screw until it will idle. Check for vacuum leaks (insert usual atmo bov/loose spring question here).

You could just have a faulty aac valve. By disconnecting power it cannot increase or reduce the amount of air the engine can breath. If the idle still hunts then it's something else, if it stabilizes then it's the valve.

[paulr33]

theres a thread in the tutorial section on how to debug idle hunt and the aac valve. i dont think it has a voltage, its a mechanical valve/flange

[Mulkers]

thanks paul. I'll check it out.

[Sumo]

On the R33 the Idle speed controller is a stepper motor.... Winds in and out like the commodores.

How would it know to idle up for air con?

Cheers

Sumo

[Mulkers]

Stepper motors can have over 200 different positions... but O.T.

This is about the AAC Valve (I think,) I had a good look at that thread, and most inoformation was useful, but didn't solve the problem. What other reasons coudl there be for a unusually high idle?

[N I B]

All Nissan's use PWM 2 wire idle valves not stepper motors.

RB20s often size the cold idle valve open (Bimetal spring controled) and idle fast causing the over run fuel cut to hunt.Block this of and see if it stops the problem.This is not the idle speed valve remember but the warmup valve.

[Sumo]

Ahh, sorry for the misinformation.

Sumo

[Mulkers]

Yes, it does not hunt when cold. Or when the AC is on.