AE101 GT issues

[RS13]

Just purchased an AE101 GT sedan, solid car but its' idling very low/stalling when cold (almost sounds like its' running on three just before it dies), once warm its' perfectly fine. Ideas? Is there a ICV or something I should be looking at? Hadn't been driven in a couple of months.

[whynot]

I wouldnt be supprised to find the ICV all gunked up and non operational. It seems pretty common on the older 20 valves. give it a good soaking with brake/carbie cleaner and it may come right

[RS13]

Awesome, thanks mate, will try it. Looks like someone may have been playing around with the screw on the AFM, I can't recall what its' for, idle mixture or something? Is there a reset position for this?

[whynot]

I don't know about a reset position for the screw but i had a play with my old one as it had been tampered with and didn't notice much difference.

My ICV valve was so bad I had to run it through a ultrasonic cleaner a few times before it would even move. You can pull the electrics off it and manually open and close it to help dislodge the gunk but mark on it exactly where it came off as it's adjustable

[sergei]

Awesome, thanks mate, will try it. Looks like someone may have been playing around with the screw on the AFM, I can't recall what its' for, idle mixture or something? Is there a reset position for this?

Only way to reset it at home is to adjust it until VF signal is at 2.5V continuously. Providing your Oxygen sensor is ok you will be able to read VF and see which way you are going. VF signal is read between earth (E1) and VF pin on the diagnostic tab. VF signal only have 5 steps (0V 1.25V 2.5V 3.75V and 5V).

0V ECU is compensating lean condition (when Oxygen sensor is dead or some other fault occurs it will be at that level) At this level ECU adds ~ 20% more fuel.

1.25 is compensating slightly lean condition

2.5 Ideal running condition.

3.75 ECU compensates slight rich condition

5V ECU compensates very rich condition. At this level ECU will reduce fuel by up to 20%.

Remember VF will go to 0V at near WOT or WOT, also when engine is not warmed up or for any other reason ECU is in open loop mode (fault detected).

The compensation is relative to either base map or on later models long term fuel trim.

If you unscrew the adjusting screw it will adjust idle mix towards lean, if you screw it in - mix will go toward rich. It idles best at slightly rich.

[RS13]

Awesome, thanks mate, will try it. Looks like someone may have been playing around with the screw on the AFM, I can't recall what its' for, idle mixture or something? Is there a reset position for this?

Only way to reset it at home is to adjust it until VF signal is at 2.5V continuously. Providing your Oxygen sensor is ok you will be able to read VF and see which way you are going. VF signal is read between earth (E1) and VF pin on the diagnostic tab. VF signal only have 5 steps (0V 1.25V 2.5V 3.75V and 5V).

0V ECU is compensating lean condition (when Oxygen sensor is dead or some other fault occurs it will be at that level) At this level ECU adds ~ 20% more fuel.

1.25 is compensating slightly lean condition

2.5 Ideal running condition.

3.75 ECU compensates slight rich condition

5V ECU compensates very rich condition. At this level ECU will reduce fuel by up to 20%.

Remember VF will go to 0V at near WOT or WOT, also when engine is not warmed up or for any other reason ECU is in open loop mode (fault detected).

The compensation is relative to either base map or on later models long term fuel trim.

If you unscrew the adjusting screw it will adjust idle mix towards lean, if you screw it in - mix will go toward rich. It idles best at slightly rich.

Thanks for that Sergei. I cleaned the ICV, no change, so gave the screw a turn anti-clockwise, and the idle has come right, hunts a little bit but doesn't stall like it did, I'll check the voltages tomorrow.

[Mr Revhead]

Isn't there a number stamped on the casting that denotes the stock setting?
Ie an 11 means 11mm from the top?

[RS13]

Hmm. Having a few other issues with the car now, thank f**k for the CGA!