500rpm Idle when in Drive.

[Z2TT]

Hi,

I've noticed that when I'm at the lights in D with the foot on the brake the car will idle at about 500RPM and is quite shaky, I'm wondering is 500RPM too low of an idle speed.

Compression is even, plugs and leads are good. I've checked for vacuum leaks and found none. At night when I have the lights on Idles even rougher when in D, if say I'm sitting at the lights idling and a passenger uses the power windows, car would become a bit more shakier.

Any suggestions, I was thinking it could be an ISCV but I thought that bad ISCV's only caused high or erratic idle?

Thanks.

[greywolf]

What's the idle like at Park and at Neutral ?

[Kyosho]

Sounds like an idle control problem.

Is your idle control valve still functioning?
Whats it idle at when in park? The switching on the trans may not be telling the ECU that you're in gear and to idle up either.

[woggin]

there is a little cap on the right side of the AFM, pull it off jam a flathead screwdriver in there and screw out (anti-clockwise) the screw is the idle bypass!!! it should increase your idle!! if not, check for codes and go from there!

[Dale]

there is a little cap on the right side of the AFM, pull it off jam a flathead screwdriver in there and screw out (anti-clockwise) the screw is the idle bypass!!! it should increase your idle!! if not, check for codes and go from there!

I think you mean the one on the throttle body... the one on the AFM is capped off for a reason

[Z2TT]

greywolf - Park the idle is about 800RPM, Neutral about the same, maybe 650.

Kyosho - Park is about 700RPM or 800, as for the idle control valve, when i turn the car on when cold, I think it does work as in it brings idle upto about 2000 RPM, then as the car warms up goes down to 1800, 1500, 1200, 1000 800 etc, so would that mean the ISCV is functioning, or could it be somehow causing a problem with too low idle, if I'm right to increase idle the iscv opens, and to decrease it closes, so is the valve closing too much thus decreasing idle too much?

Woggin - isn't that just an idle air mixture screw?, I played around with that on my old car, just about 2 turns either way and it did nothing.

Dale - I dont see any screw on my throttle body, will have a look again though.

[greywolf]

Sorry, didn't get what car you are driving.

Does your car run a MAF ? Sometimes a dirty MAF sensor screws your idle.

[Z2TT]

I have a 1g-gte, It uses a flap type AFM so that wouldn't be the cause.

[woggin]

I think you mean the one on the throttle body... the one on the AFM is capped off for a reason

no, i mean the idle mixture screw!!! as per Z2TT said below your post

[Dale]

Dale - I dont see any screw on my throttle body, will have a look again though.

http://www.toymods.net/forums/showthread.php?t=4624

Found this thread while looking for a picture of a 1ggte throttle body, judging by the first photo in that thread it looks to me like the idle adjustment screw would be under the little black cap near the TPS.

Will let someone with more knowledge of 1g's confirm/deny this

no, i mean the idle mixture screw!!! as per Z2TT said below your post

Yes but it's a mixture screw, it's not there to adjust your idle speed and generally shouldn't ever need to be adjusted.

[Kyosho]

I'd be looking for the idle bypass screw,
i never paid too much attention to my 1G to know where it is, on my R33 it is on the ISCV itself, so I'd start by looking there...

[Z2TT]

Kyosho is that screw supposed to let air enter the inlet manifold from another point other than the throttle body? The ISCV does that and is controlled electronically by the ECU I think, I had a look at the ISCV but didn't see such screw, However yes near my throttle body there is a screw.

Today I took apart my ISCV and cleaned it out, didn't help.

[JZX083]

Is the stop signal from the brake pedal getting to the ECU to say you have your foot on the brake and to unlock the lock up clutch????

[Z2TT]

Is the stop signal from the brake pedal getting to the ECU to say you have your foot on the brake and to unlock the lock up clutch????

I'd think so otherwise wouldn't I get a check engine light?

I was using my old soarer wreck to find out which wire is for the stop light signal for the ECU, couldn't quite figure it out, I cant find a wiring diagram for the GZ20 either. ECU pinouts for the 1g-gte didn't help much.

[MrStroker]

Have you tried adjusting the throttle position sensor?
You can change the difference between idle speed in P/N and in D/R.

Have a play adjusting as will take trial and error to find best position.