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High idle GTR

Dash

By Dash,
in General Maintenance

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Dash Enthusiast

Dash

Posted
Posted

Since last week my car has started idling high

It used to sit on 950 rpm

Now its up around 1400rpm

Doesnt appear to have any cold start correction either just stays, high hot or cold?

Runs fine but the high idle is starting to shit me.

Anyone know what could be wrong?

Any suggestions before I take to a mechanic?

Thanks

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Chris32 Veteran

Chris32

Posted
Posted

My GTSt used to do this,

I found 2 vacuum leaks, and it fixed the problem

Check on your boost gauge at idle, with no vacuum leaks it should read around -0.5bar

Hope this helps

P.S - my leaks where on the vacuum line going to the stock boost gauge and one on the fuel pressure regulator line

Chris

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Dash Enthusiast

Dash

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mine idles that high all the time, stalls if i give it a bit and back off if the idle is any lower, maybe it thinks the aircon is activated?? does turning the AC on or off effect it??

Nah Ive checked both AC switch and power steer switch (pulled them out no change)

Engine temp sensor raises idle when taken out so not that.

Chris32

You could be right as I was out driving one night and after giving it a bit I noticed

the revs werent dropping down.Finding a leak is the problem.

Nothing is easy to get to in the engine bay.wanted to pull out the AAC valve to check but that means off with manifold,throttle ,linkages etc.

Im sure the designers of these things were the size of Leggo men with hands to match!

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Dash Enthusiast

Dash

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adjust the throttle position sensor. Remember to mark in exactly where it was b4 just in case so you know where it was b4. When i say mark it in, mark it in properly cuz like 1 mm will affect.

Thanks but I dont think that'll work as idle remains unchanged when TPS is disconected.

AAC valve screw is turned all the way in.

Took it apart and it was pretty clean,gave it a blast with cleaner anyway no difference!

Anyone know if the solenoid is suppose to rattle when shaken?

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Godzilla32 Veteran

Godzilla32

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Posted

My R32 GTR is idling high too but thats after i took the whole intake collector off..a way to see if you have leaks is by spraying aero start. It will make the revs pick up when and if there is a leak around your mannifold etc..Mine hasen't shown any sign of that when i tried it but it can get as high as 1900rpm after driving...i took off my AAC valve and cleaned it out i will get a new gasket for it but i dont think thats the problem..Also since this happened i lost all boost..I thought a vacuum line could be the problem..seems more like the wastegates arent closing to build boost than a turbo failure...So i need help with this too..how can i test the stock boost control solinoid...?? Any ideas? i have a completley stock GTR. Thanks

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Syphon Rising Star

Syphon

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Posted

I havent worked on these motors before but if they are anything like the RB30, then you should have an air regulator which controls your cold start. If the air reg jams open, it bypasses more air into the inlet thus ending up with a wildly high idle once the motor has warmed up.

Sounds very similiar to what an RB30 does with a jammed air reg. Mine tended to rise the warmer it got until it was idling at 1200rpm...

If there is infact an air reg, warm the motor to operating temperature, pop the hose off the top of the air reg and check to see if it has closed completely. If its still open, there is your problem most likely.

Otherwise as suggested a vac leak somewhere along the lines.

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ylwgtr2 Grand Master

ylwgtr2

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carefully pick out all the epoxy from the aac valve(you will see a epoxy patch about the size of a 5 cent coin)...underneath this you will see a screw and behind the screw is a spring...if you aac valve rattles then this has lost its tension....pull it apart clean it out and stretch the spring or turn the screw down further(i do both) then re epoxy the screw head....

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  • 3 weeks later...
Godzilla32 Veteran

Godzilla32

Posted
Posted

Can anyone confirm that there is infact meant to be a slight build up around the butterflies int he throttle bodies? I thought it was just carbon build up so i got rid of it to improve flow hehehe and now its idling high. The mechanic told me its mean't to be there...Anyone?

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NA_R33 Grand Master

NA_R33

Posted
Posted

your mechanic is correct, cars are designed to run with certain amounts of carbon deposits around the place, the trick in the old cars used to be to poor water down the intakes to clear excess build up.

edit: shouldnt really dramatically effect your idle though unless it was making up for worn butterflys??

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