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The mkiv Supra Owners Club

Low idle problem


Robert

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Hi guys,

i'm having a problem with the idle on my car since i got the car back from the bodyshop. The problem is when i start the car it will idle at around 1000 rpm for about a 30 seconds then it will slowly drop all the way to abut 500-550rpm. It sounds like the car is going to die, and twice has. I have a brand new battery and i've done a mini service by changing all the fluids and oil filter. I've also reset the ECU and still no good.

Any idea's? i dont feel comfortable driving the car with the way it is currently thats why i cant get to a garage.

 

:thanks:

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Has the car been stood a long time?

 

Whilst mine was garaged, it did the same thing. Kept cutting out every so often without warning. Doing like yours too high idle when starting which would then drop. Thats probably a automatic choke though.

 

My cutting out problem completly stopped when i put a fresh tank of fuel in the car. I therefore put it down to my petrol going off while stood.

 

Give it a try if your car has been stood, if not i have no idea im affraid

 

Hope you sort it :thumbs:

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Yup the car has been standing for about 4 months, When i collected the car it was empty so i had to get a 10 litre can an fill the car with that but apart from that i haven't added any more petrol.

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its just getting to a petrol station that is the problem. I just took the car for a quick drive(about 200 meters) and parked it back now its revving at 450rpm in P. The revs stayed at 550 for about 3 mins then went down to 450rpm, i decided to park it back at home before it drops any lower.

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i thought it might have something to do with the IACV because when i got the car back the engine bay was a complete mess,covered with all sorts of rubbish and dust from the bodyshop. Ive cleaned it up the best i can, but still the same problem.

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You'd be suprised. Check especially the MAP sensor hose and anything t'd off it.

 

If you need to get to a petrol station, try taking the PAS valve bypass hose off the intake plenum (its the hose nearest the PAS reservoir) so that some air bypasses the throttle and raises the idle. (note - doesn't work with MAF based cars).

 

-Ian

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ok, i've got an update on things, it seems as though the intercooler hoses weren't fitted properly and were loose so ive sorted the upper parts of the hoses out,i will check the lower parts of the hoses tomorrow when i take the battery out and change the rusty connectors. The main thing that confused me was that when i turned on the AC the revs didnt go up, the AC works fine but usually the revs would go up, maybe thats a clue to the problems im having?

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ok, i've got an update on things, it seems as though the intercooler hoses weren't fitted properly and were loose so ive sorted the upper parts of the hoses out,i will check the lower parts of the hoses tomorrow when i take the battery out and change the rusty connectors. The main thing that confused me was that when i turned on the AC the revs didnt go up, the AC works fine but usually the revs would go up, maybe thats a clue to the problems im having?

 

 

Dude it really sounds like you need to get the car checked out properly , you seem to be having a lot of little problems , maybe theres a bigger one lurking .

 

Dude :littled:

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ok, i've got an update on things, it seems as though the intercooler hoses weren't fitted properly and were loose so ive sorted the upper parts of the hoses out,i will check the lower parts of the hoses tomorrow when i take the battery out and change the rusty connectors. The main thing that confused me was that when i turned on the AC the revs didnt go up, the AC works fine but usually the revs would go up, maybe thats a clue to the problems im having?

 

Normally the idle control valve cracks open a bit and lets on more air to up the idle. If you've got a mirror you can take the air feed hose off the ICV and use the mirror to watch the plunger. If it moves and the idle changes, it's working. If you have taken it off, don't forget to check the state of the one way valve it feeds in the intake manifold.

 

If it's MAP based, btw, loose intercooler hoses wouldn't make jack all difference to the idle speed :( The MAP sensor measures the air in the manifold itself so air leaks increase the speed of the engine as it bypasses the throttle plate, feeds the engine more air and it gets metered and fed with the right amount of fuel. It's MAF based cars that underfuel and end up with a rough idle with air leaks.

 

-Ian

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