Idle Problems -Computer indicates no problems


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Idle Problems -Computer indicates no problems

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TangledUpNBigBlue
New User

Jul 24, 2008, 10:20 AM

Post #1 of 3 (1754 views)

Idle Problems -Computer indicates no problems	Sign In

I own a 2000 Galant which until recently has been a very dependable car. Last September the original battery died & I had to have it replaced. The guy at the service center took over an hour to replace it and in the meantime of course the radio shut down and the engine computers all reset upon connection of the new battery. Since that time I have had numerous problems with the car’s idle and performance. As a result I have had to replace the idle control monitor & in the last two months the car has been in the repair shop some four times including 3 times at my local Mitsubishi dealer who is unable to determine the problem as the computer indicates the car is working properly even though the idle increases & decreases markedly on its own & the car stalls and dies frequently. Now the tachometer needles bounces like a superball, the car stalls and dies frequently. Please help!

autojoe
User

Jul 25, 2008, 7:53 AM

Post #2 of 3 (1741 views)

Re: Idle Problems -Computer indicates no problems	Sign In

the dealer should have the tools to isolate problem.There is probably a short somewhere.The person that changed the battery might have disturbed some wiring somewhere.Check wiring near battery.There is a procedure called an idle relearn that is done after replacement of idle air control motor.The tach bouncing all around....may be a problem with the crankshaft position sensor or circuit.Would need to hook up scan tool and look at rpm on scan tool.If varying bad would have to trouble-shoot that circuit with labscope.The crankshaft position sensor if this is a dis vehicle tells computer the rpm signal so computer can calculate spark timing and also fuel injector pulses.The tach needle bouncing and stalling is a good indicator to check this out.What did the dealer say about the tach needle bouncing all around?

dave284
Enthusiast

Jul 25, 2008, 8:27 AM

Post #3 of 3 (1740 views)

Re: Idle Problems -Computer indicates no problems	Sign In

I have ran into such problems as what you have posted, airflow meter was one and the other, idle air control unit.....and most times when the tach starts jumping, I would be checking out the speed sensor. Also check for vacuum leaks were the unit was replaced....that is one of those things that can be easily overlooked.

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