High idle

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colin22

New Member
When warm my car is idling very high at about 1500. It then starts to climb to about 1700 and will stay there. On cold start the car idles low at about 1000rpm and as it warms up, the idle speed gradually rises. The car drives very smoothly; I'm just having idle issues. I just got this car a couple days ago and the previous owner told me it was aftermarket cams but I'm not sure if I believe him. I took a quick look at the idle adjust screw and it looks to be tightened all the way down. Tomorrow I'm going to confirm that, but can anyone help me quickly diagnose this issue? Thanks.

UPDATE: I smoked the test the system and found it was leaking at 1 of the fmic couplers and fixed the leak. The car now idles at 1000rpm. I also replaced cap and new spark plug wires. The problem I'm having now is loss of power. The car builds boost really quick now, faster than before, but now it's really slow. Car doesn't go at all, feels like a honda civic. Do you guys think it's because the smoke may have messed with the MAF sensor? I'm going to try to clean maf tomorrow.
 
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BMCC

Member
On mine high idle was caused by the PCV pipes on the inlet manifold being perished, the bigger PCV off the rocker was a well. Also check that the throttle balance blanks on the inlet manifold (if you've got a standard top mount cooler you will see the one nearest the belts if you follow the top edge of the cooler, there are 4 off them make sure they are there and that they seal down properly). Also check that the throttle closes properly.
 
gtir_pimp

gtir_pimp

New Member
Cams won't effect the idle like that, the car would tick over rough depending on what cams you have almost like it's chugging if that makes sense.

ive had a few pulsars that would do the opposite and idle high when cold but settle down when warm.
 
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colin22

New Member
Changed the pcv valve and it still idles high. I noticed that 2 of the ports for the throttle adjusting screws are missing the black plugs. Could that be it?
 
johnny gtir

johnny gtir

Well-Known Member
The caps on the part where you use it to balance them or the actual screw caps ( dont think there capped) then yes it will massivly effect idle
 
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colin22

New Member
The black plugs. So i plugged off those ports with some random plugs i found and wrapped the pcv valve with some plumbers tape and the idle now idles a about 250rpm lower at about 1250. I read that you're suppose to adjust idle with the tps sensor unplugged. I'm thinking maybe thats the culprit because ive adjust idle all the way down but didnt unplug sensor. How do i unplug that sensor? Theres a whole bunch of crap in the way.
 
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colin22

New Member
Lol nevermind, I found the plug. The car idles better now. It idles at 1250 but will rise up again to 1500. Then if u let it sit for awhile it'll slowly go back down to 1250.
 
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colin22

New Member
It's hard to ignore, I'm picky lol. Is it possible to take off the iac unit without removing the intake manifold? I want to check the aac.
 
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BMCC

Member
The black plugs are the throttle balance ports which I mentioned earlier, You may also find that at the others look ok but actually sit a few mms off. 3mm hose them one to the other and they should seal up. You need to pull the TPS for the idle but if you have turned the screw all the way in on the IACV then you are not going to be able to adjust the idle. If you want to unplug the sensor then it is easier to take the top mount off and get at it this way. Also helps if you have small hands...............
 
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BMCC

Member
You adjusted the tps? To get base idle you pull the plug on the tps rather than turn the tps. There are voltage figures in the manual for what the tps should be reading when the throttle is fully open and fully closed.The manual has the procedure for checking base idle which from memory is get the car up to temp then turn off the engine pull the tps connector restart and see if the idle is about 850 rpm if not then you can turn the idle adjust screw in to lower the rpm. Pulling the tps connector should stop the ecu adjusting the ignition timing and speeding up/down the idle.
 
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colin22

New Member
So I just pulled the hose off the pcv valve on the valve cover and plugged the hose off. The pcv valve is now venting to atmosphere. The car now idles at 1000rpm. Is it ok I did it like this?
 
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BMCC

Member
There is info on here about how to delete the pcv from the engine. Personally i wouldn't vent to atmosphere. Have you checked all the pcv pipes as there are many on the inlet manifold?
 
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