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Sticky idle / Idle a bit high.


fuldhat

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Hi again

 

Old Thread: http://www.mkivsupra.net/vbb/showthread.php?243750-Sticky-idle-when-driving.

 

(1993 TT6 j-spec)

 

Just been testing and checking it this weekend and this is the sitiuation:

 

Start from cold is fine and the revs will not hold and drop down normaly as the engine warms up to around 7-800 rpm.

 

When driving, and the engine is warm, then once you press the clutch, then the revs will hold anywhere between 1300-1900 rpm, until a quick blip on the throttle and the revs drop down til just under 1000 rpm.

 

It is 100% not the cable, and it will also hold the revs, when you are just standing still and keep the revs at 1500 and release the throttle.

 

I have checked the O2 sensor and got a reading around +0.8 - 0.9 v, so it running a bit rich, so I have ordered a new O2 sensor, but could that be cause?

 

I am going to clean the Idle control valve one of the next days also, but if a quick blip on the throttle can "fix" it, then it would be strange, that the ICV could be cause.. I am right?

 

Any input would be great:search:

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I have not checked this, but as written in the first post, at quick blip on the throttle, and the revs drop down to just under 1000 rpm. So if the TPS was incorrect, it should show all the time correct?

 

Is your TPS set correctly?

 

An incorrectly set TPS can cause high idle when in neutral or the clutch disengaged.

 

Id also recommend checking your throttle valve isnt sticking aswell.

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I have not checked this, but as written in the first post, at quick blip on the throttle, and the revs drop down to just under 1000 rpm. So if the TPS was incorrect, it should show all the time correct?

 

Incorrectly set TPS would, sticky or faulty TPS would show the issues you have.

 

I used to have this with my MR2, it was the throttle valve for me. Think I used some brake cleaner or something like that. It will be oil/carbon buildup making the flap a bit gungy when closing (hence why a blip can clear it).

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Incorrectly set TPS would, sticky or faulty TPS would show the issues you have.

 

I used to have this with my MR2, it was the throttle valve for me. Think I used some brake cleaner or something like that. It will be oil/carbon buildup making the flap a bit gungy when closing (hence why a blip can clear it).

 

Aha, okay well I just searched for how to adjust the TPS. Will get that done.

 

I am going now to buy some brake cleaner, and then I will clean out the valve, to see if that helps

 

Thanks so far. I will report back with results

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Aha, okay well I just searched for how to adjust the TPS. Will get that done.

 

I am going now to buy some brake cleaner, and then I will clean out the valve, to see if that helps

 

Thanks so far. I will report back with results

 

Bit of crossed wires there. I don't think it will be an ill adjusted TPS as it would be a constant issue rather than an on and off one (I was agreeing with you that it wouldn't be the adjustment). It would point to it either being faulty, sticky or the throttle valve being sticky. My money would be on the throttle valve to be honest. The TPS is pretty strong and when it breaks it usually just goes completely tits up from what I understand.

 

Run your car easy for 10 mins after using the break cleaner. I wouldn't be surprised if you saw some flames lol.

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You'd be surprised. TPS was one of the problems when mine would hold high revs and drop up and down on idle.

 

Surely that was a gubbed TPS though? Rather than one set wrong? It's a resistance value, if the resistance value is wrong the angle of the valve is wrong and will lead to higher or lower revs. If it has a bit of play in it you could get idling issues, but I can't see how a setting would be variable... it is afterall a setting :D

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Okay, Well my first point during easter, will be to clean everything around the TPS, and the TPS valve/intake and then I change the O2 sensor. Then I will have to see, if that helped.

 

It has slowly gotten worse, so it could be just dirt/sludge causing it.(hoping so)

 

I will report back

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