Idle problems

[Steve]

My car's idle has been pretty poor. Revs quite high when cold, and hunts continually when hot and when cold - even worse when the air con is switched on. It used to idle fine, this happened all of a sudden.

I have a power fc fitted, but it seems to be working properly. I thought it might be the O2 sensor as it doesn't have a constant voltage output, but ruled that out as the hunting will cause the O2 to fluctuate???

The car runs fine at cruise, and under power.

Has anyone had similar problems, or have any ideas as to what may be the cause.

PLEASE HELP

[GTS-t VSPEC]

Steve,

The best way to diagnose the problem is on a dyno, I know it cost's money but compared to the hassle of going through all the possibilities it will be worth it.

Other than that it could be plugs, injectors, O2 sensor, temperature sensor, fuel pump etc. The list of possibilities is quite long, a dyno will narrow that down very quickly and then you can have a happy car again.

See'ya

[fatz]

i found that power fc's dont like light flywheels

causing a hunting as you said

changed to standar and it came goood

[blind_elk]

Clean the AAC valve.

[Steve]

Thanks heaps for your replies:)

GTS-t VSPEC:

I will be dyno tuning the car again soon, just waiting for the Z32 AFM. Can you recommend anyone in Perth?

fatz:

don't have a lightened flywheel YET - thanks for the tip though as this is a future planned mod.

blind_elk:

What and where is the AAC valve, and is there a specific way to clean it?

[GTS-t VSPEC]

Steve,

There are quite a few good tuners in Perth, I tend to use either Steve at SST or Barry from Barries Dyno. How much is the Z32 AFM costing? I run a map sensor, therefore no restriction from the AFM, does the PowerFC have map sensor capability? There is also a VPC (vane pressure converter) from HKS or someone that provides the equivalent electrical signal without the restriction. It's just for the cost of the Z32 AFM I think there are better alternatives, but that's my opinion.

I would have thought the hunting is a fuel related problem. Good luck with the retune.

See'ya:burnout:

[RAIDER]

i beleiev your air flow meter is the issue

fix taht up and enjoy the ride

[Steve]

GTS-t VSPEC:

Thanks again, the Z32 is costing $270Aus which isn't a bad price. The reason I don't want to go map is that it seems to raise some problems with fuel usage at idle and cruise and from what I heard takes a bit to set up properly, with the added advantage that upgrading the turbo doesn't require a complete retune. I may be way off the mark, but I was under the impression that MAF is alot more street friendly than MAP. The Power FC has an option for a Z32, so its a pretty easy install and then a dyno tune, and I believe not compatible with MAP?

RAIDER:

Cheers for the input, I'll give it a go and see what happens. Fingers crossed

[GTS-t VSPEC]

At that price for the Z32 you'd be crazy not to buy it. Yes in general I would agree with most of the fuel issues relating to the MAP, but most decent tuners can set it up no problems. It depends how far you want to go with your setup, as even the Z32 will run out of range with a decent turbo.

Seeing as the power fc takes the Z32 directly then it is a good choice, I hope it turns out well once you've had it retuned.

See'ya :burnout:

[Steve]

Thanks heaps for all your replies.

I took the AFM off and it was black with god knows what (perhaps running a K&N pod didn't help as they are oiled). Hit it with some brake cleaner and presto - problem solved:D

Raider - nice call and thanks again

[GTS-t VSPEC]

Steve,

The pods with the oil will tend to give your AFM the shits, but they are great at filtering out fine dust. Either regularly service your AFM, or move to a non-oil based pod.

Glad to hear your problem is fixed.

See'ya:burnout: