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Hello, Ive got a problem with a USDM 85 AW11. The car doesnt seem to idle when cold. it hunts when hot. it was like this after timing belt replacement, I confirmed the timing was correct. I can keep the car running by blipping the throttle when cold. but it then chokes at around 500-600rpm. when its hot its hunting around 800, the shop replaced the afm, tps, coolant temp sensor, the auxiliary air valve is working properly. Ignition timing is correct. Im stumped guys.
 

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... it was like this after timing belt replacement..

... I confirmed the timing was correct...

... I can keep the car running by blipping the throttle when cold. but it then chokes at around 500-600rpm..

...when its hot its hunting around 800...

... the auxiliary air valve is working properly..
Who did the replacement? You or a shop?

Did you check the valve timing as well as the ignition timing? One of the gears a tooth off would be a primary suspect.

Not sure what you mean by this. The engine won't go above 600rpm?

Not sure what you mean by this either. 800rpm is the correct hot idle. Maybe you could be more specific.

I don't see how you would determine this if the car doesn't idle cold.
 

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it doesnt idle cold, if you dont give it gas itll cough at 500rpm or so and then die a few seconds later
I checked the cam and ignition timing. shop did the replacement because Im lazy as hell.
It hunts when hot. not sure how that is confusing, its 800 +/-200rpm or so.
 

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When the shop "shotgunned" all those parts, they may have cause more problems than they fixed. Each sensor can be tested. I hope you kept the old parts.

Did they replace the water pump when they did the timing belt? If so, I'll guess air in the coolant, or a vacuum leak.
Since you are "lazy as hell", perhaps bring it to a different shop?

good luck
 

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If all it needs to run is more air, then it sounds like the auxiliary air valve is not actually working. All that does is supply more air when cold. Does the car drive ok?
 

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I would guess that rmeller is on the right track with the AAV. Remove the AAV and try cleaning it with carb cleaner. They can gum up, so let it soak for 5 to 10 minutes. Then flush it several times. Also verify that the water ports on the AAV and lines are not restricted. davew
 

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With my 89 SC I had a similar issue, I don't know if this would apply to the NA MR2s.

The issue with mine was caused by the ground for the cold start injector timing switch. The fix was simply cleaning up the surface that the timing switch bolts onto with some emery cloth.
 
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