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Discussion Starter #1
My R33 gtr idle is arround 1050rpm so not that bad but when I slowly test drive the car on my driveway the idle wil go to 2000rpm stick there when I blip throttle it comes back to 1050 rpm

I also see throttle sensor at idle 0.40V at 2000rpm 0.51v so could this be throttle position sensor problem or anything else ?

thnx
 

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To be honest sounds bit strange to me but I am not an expert But on any case the TPS should be at 0.4v at idle if my memory doesnt fail.

Have you checked the IAC valve?
 

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Discussion Starter #3
The TPS is at 0.4V at idle but I think it also could be a throttle cable problem , it looks lik the throttle cable or bodies get stuk just before full closing but this is only when car is running when car isn't running I can push the throttle as many times as I want it Always goes to 0.4V so full close .
Does the TPS only read or can it also adjust throttle , what I mean is can itself open or close the throttle bodies ?.
 

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I believe it is just a sensor, doesn't control the throttle. Have you tried some WD40 on the spring under where the throttle cable attaches to? Have you changed anything on the ITB's lately?
 

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Discussion Starter #5
the itb got complete clean and reseal .
problem is the car is idling fine it just looks like the throttle is getting stuck a little bit and when I blip the throttle its back fine .
Thats what I noticed on the sensor reading idle is 0.4v than when I push the throttle 20 times when car is not running it Always returns to 0.4v but when the car is running it idle fine at 0.4v running few meters and it reads 0.51v than just little tap to the throttle pedal and it drops back to 0.4v and normal idle So Its posseblie something that gets stuck a but only when car runs and thats weird
 

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I haven't resealed mine yet (currently overhauling the ITB's with Reimax seals) when I took one of them apart it wouldn't always close 100% as one of the butterflies was the wrong way up. Only a tiny difference, but it wouldn't always close fully. It did if you gave it a little push. I'm not saying that's what happened with yours, could it be a little too much throttle coat making it stick? As you say, the different TPS reading suggests it isn't closing 100%.

Have you driven the car since? Does it do it after driving, or only when idling? :unsure:
 

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Discussion Starter #7
Thats what I also was thinking but the weird thing is it always fully closes when the car isn't running thats the weird thing .
its a full rebuild engine etc with apexi power fc rest zo idle relearning etc
I only have driven the car here for 10 meters up and down the driveway .
Also when I rev the car when standing stil it sets Always back to normal idle its only when I let the car run few meters its doeing the high idle so therefore I thought when the engine gets little load the air fuel , ignition is not good so it would run lean or rich and the tps was giving more air or fuel .
 

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That is strange :unsure: Could it be the cold start valve? (I think that is what it is called) does it do it when the engine is up to temperature?
 

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Has the aac valve been stripped and cleaned ?. did mine years ago , idle has been perfect ever since .

Lee.
 

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If your TPS is defective it can cause idle RPM to race up like that, usually idle base engine timing is not advanced for peak power but quite a bit lower to allow for controlling the idle with ignition timing.
 

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Discussion Starter #11
That is strange :unsure: Could it be the cold start valve? (I think that is what it is called) does it do it when the engine is up to temperature?
Yes it does it when engine is up to temp
Has the aac valve been stripped and cleaned ?. did mine years ago , idle has been perfect ever since .

Lee.
Yes cleaned it all out

Did find a leak in my fuel line so maybee the engine loses fuel pressure, starts running lean and therefore it maybee goes up on rpm
really need to have a look today if the TPS can add throttle itself or not going to see howm uch the TPS voltage is when engien startup and is cold then the rpm is little higher so I look what TPS voltage readings I got
 

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Discussion Starter #12
replaced fuel line , looked at tps sensor all sooms to be ok
I think it got something to do with the throttle bodies and vacuum pressure maybee
is it normal you can push the throttle verry easy when car is not running and when it runs the throttle feels much harder ?
 
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