Idle problem on start
05-01-2014, 11:12 AM
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Idle problem on start
I have an ap1 and at times when i start the car and the car is warm the rpms drop really low to about 300 rpms making the car to shake almost like its gonna stall and back up to normal revs. can anyone help me with this? thanks!
05-01-2014, 12:10 PM
#2
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Our cars have a learning ECU, and at times, need to adjust things idle control based on changing climate conditions (temp, humidity, etc).
Possibility 1 is that something has changed, and the ECU needs a few days or a week to re-learn how to properly maintain idle. When this happens, do not give the car gas. Let it raise the idle itself. If it doesn't raise the idle after a bit, or stalls, then that's probably not the issue. If it takes more than a couple days to re-lean the idle, that's probably not the issue. Some people have luck re-setting the ECU, then letting it idle for 5-10 minutes, so you could try that..
Possibility 2 is that your map sensor is blocked. The map sensor sits on top of the throttle body. There is a very small air channel that runs between the TB and the intake manifold that feeds the map sensor. This air channel gets clogged and the sensor gets bad readings, and idle is affected. You can unbolt the throttle body and clean out the channel.. quick and simple, and you probably won't even need to use any solvents (This happened to me. I opened it up, and cleaned it with a rag, and it's been 100% fine for 30k miles).
Possibility 3 is that your idle air control valve is dirty, and not opening/closing properly. IAC is located on the side of the intake manifold. It has an electrical connection and two coolant connections. You need to remove it completely to access the internals of the valve. There is a DIY writeup somewhere on here that I would follow so you don't harm anything in the valve.
I'd place a hefty wager that one, or a combination of these things, is the problem.
Possibility 1 is that something has changed, and the ECU needs a few days or a week to re-learn how to properly maintain idle. When this happens, do not give the car gas. Let it raise the idle itself. If it doesn't raise the idle after a bit, or stalls, then that's probably not the issue. If it takes more than a couple days to re-lean the idle, that's probably not the issue. Some people have luck re-setting the ECU, then letting it idle for 5-10 minutes, so you could try that..
Possibility 2 is that your map sensor is blocked. The map sensor sits on top of the throttle body. There is a very small air channel that runs between the TB and the intake manifold that feeds the map sensor. This air channel gets clogged and the sensor gets bad readings, and idle is affected. You can unbolt the throttle body and clean out the channel.. quick and simple, and you probably won't even need to use any solvents (This happened to me. I opened it up, and cleaned it with a rag, and it's been 100% fine for 30k miles).
Possibility 3 is that your idle air control valve is dirty, and not opening/closing properly. IAC is located on the side of the intake manifold. It has an electrical connection and two coolant connections. You need to remove it completely to access the internals of the valve. There is a DIY writeup somewhere on here that I would follow so you don't harm anything in the valve.
I'd place a hefty wager that one, or a combination of these things, is the problem.
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