High idle TB42E

[zmaster]

As the title suggests, my Gq TB42E auto, has a high idle, was at 1100rpm in neutral, using the screw in the back of the manifold, i've dropped it down to 950rpm. Should I keep winding the screw until it drops further, I've wound a fair bit, or should I be looking at something else? Looking at the ecu talk readings would tell me something if I knew what they're suppose to read!

[Bloodyaussie]

What screw?? I use the TPS to adjust mine and it sits at about 850-900rpm...

[Parksy]

Make sure your tps is adjusted properly. Should be at about .4 to .45 volts at idle. Then adjust the screw on the back of the manifold until idle is about 650.

[Bloodyaussie]

650?????????? never come close to that with out it stalling??? would love to get that???

[Parksy]

Check your fuel pressure and give the fuel system a good clean, bloody Aussie. Mine had a horrible idle, would stall and hunt, but these 2 were the main culprit. Also cleaning the manifold and aac valve assembly will benefit. And replacing all the vacuum tubes with new ones. All of these helped my case.

[Bloodyaussie]

I have run a injector cleaner and just done a head reconditioning treatment last week but on petrol it runs like shit, this has only happened recently.

Plugs have been checked but down low it has nothing but above 3000rpm runs as smooth as and pulls hard???

Driving me nuts as most work has been done by a shop.... will get fuel pressure checked plus a couple of other things then if it keeps up its time to change mechanics??

[Alitis007]

I have run a injector cleaner and just done a head reconditioning treatment last week but on petrol it runs like shit, this has only happened recently.

Plugs have been checked but down low it has nothing but above 3000rpm runs as smooth as and pulls hard???

Driving me nuts as most work has been done by a shop.... will get fuel pressure checked plus a couple of other things then if it keeps up its time to change mechanics??

Sure you dont have blocked injectors mate ?? Have you got an electric dizzy or points?

[Alitis007]

As the title suggests, my Gq TB42E auto, has a high idle, was at 1100rpm in neutral, using the screw in the back of the manifold, i've dropped it down to 950rpm. Should I keep winding the screw until it drops further, I've wound a fair bit, or should I be looking at something else? Looking at the ecu talk readings would tell me something if I knew what they're suppose to read!

Has the idle just gone up all of a sudden or has it always been high ? I would be looking at vacuum leaks or a blown manifold gasket sucking air

[zmaster]

idle has always been high. Vacuum is good, will chech TPS, remember reading about Temp sender could be cause?

[Alitis007]

Coolant temp sensors will only affect fuel from cold till operating temperature, then the oxygen sensor takes over and the computer stops reading resistances from the coolant temp sensor.

TPS is a good start but like i said before i'd also be looking at the vacuum hoses for cracks and splits and the condition of the inlet manifold gasket and injector "O" rings for sucking air, then i'd start looking at the AFM. Generally tho high idle is from sucking air.

On your ECU is there a dial the reads test and idle ?? EFI RB30's have one and sometimes they need to be adjusted to set the idle.

[saw13]

When i had my TB42e i had problems with the idle as well, nd i played around with it a fair bit, there is a special way to do the idle adjustment if i can remember correctly, defenitly set the TPS to 0.4-0.45 first cause that rectifies the smooth change of the auto,
then u have to disconnect the plugs on the idle control valve, its where that black screw is, aswell as the TPS plugs ,should be 2 plugs on either one,
start the engine, adjust the idle up, by whinding the screw out i think, turn the engine off connect all plugs, start it up again, the revs should drop, so just keep playing around with the idle followin thos steps, im not saying that its the problem but its worth a try,
another thing it might be it the MAF sensor, disconnect while the engine is running if no change it could possibly be it aswell, if a vacum leak grab a tin of WD40, while its running spray all over hoses, down beside the inlet manifold, just hope its not a manifold gasket lol, pain in the a**
Hope u figure it out mate
Scott

[zmaster]

Thanks for the brilliant response, I was also thinking temp sender,will measure the TPS and IAC, have ECU Talk, and laptop, temp seems to be reading fine, not sure how high it should climb, can't remember the TPS sensor reading, but the oxy sensor seemed lazy, so I'll change it out for a new one. Other issue I forgot, on stabbing the acc pedal, revs jump up to say 1500rpm, then lazily drop down to 1100rpm, before eventually dropping back to 950rpm.

[Alitis007]

Thanks for the brilliant response, I was also thinking temp sender,will measure the TPS and IAC, have ECU Talk, and laptop, temp seems to be reading fine, not sure how high it should climb, can't remember the TPS sensor reading, but the oxy sensor seemed lazy, so I'll change it out for a new one. Other issue I forgot, on stabbing the acc pedal, revs jump up to say 1500rpm, then lazily drop down to 1100rpm, before eventually dropping back to 950rpm.

From my experience that is definitely a vacuum leak so the motor is sucking air from some where, oxy sensor will make it run lean or rich @ NOT

[zmaster]

I'm thinking the same!