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Q: Rough starts and engine dies at idle

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My van has had trouble starting. When it starts, there's a rough idle, and while that's happening, the van usually dies if you try to put it in gear. Once you're moving, the problems disappear. Our van has a little over 100,000 miles on it, and has been pretty reliable. This starting issue only happens once a month or less. When it decides to have problems, they go away after one round of rough starts. I was thinking it might be the outside temperature at first, but there's no pattern. Tried changing to different grades of gas, but that didn't work either. This all started before the 100,000 mile mark, though we did have the normal things done at that time - timing belt and spark plugs. We've also changed the battery and tried using fuel additive to clean out the engine. No change. The rough starts feel like when you're missing a cylinder. When it happens, I can gun the engine without any issues, but when it drops back to idle, it dies. The biggest challenge is keeping it running long enough to get it moving. Since it isn't happening while the engine is warm or cold, I'm not sure what what else to do. Do I need to change my spark plugs and fuel filters? Anything else I should look at?

If the idle air control valve or mass air sensor is having problems. If the idle valve is sticking closed it can cause the engine to idle very low and rough, and will run fine if the throttle is held open.

The valve may come unstuck after the engine is ran for a minute. Try to have the throttle body and idle air valve cleaned out to see if the problem goes away. Also try and have the mass air sensor valve cleaned at the same time. This should fix the idle problem you are having. Otherwise a mechanic would need to verify the problem and if it only happens at first start and once a month then verifying the problem would be unlikely. Have the vehicle looked at by a qualified mechanic, who can diagnose your cars symptoms first hand and pinpoint what exactly is causing your car to die after startup.

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