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Discussion Starter · #1 ·
Just got my first car its a 2000 GT 5 speed with 110k miles. The previous owner had bought the car knowing there was a loud knocking thinking it needed new rod bearings. Other than that the car had run perfect. But the owner ended up just letting it sit outside for about 2-3 years without fixing the problem. I've always wanted one of these cars and he ended up giving me a killer deal on it so i had to buy it. When it comes into my possession, the car now has a check engine light and a very bad idling problem where it skips and every few seconds it dips down to 300-400 rpm. And of course it still has this knocking sound when it revs over 2000 rpm. Anyone have any idea what could be causing these problems. I've already checked the coil packs and spark plugs they are all fine. Added new gas to the car thinking it had something to do with bad fuel since it was sitting for so long but that also wasn't the issue. Don't know much about these cars so if anyone could help me that'd be great. Keep in mind the car has been sitting for 2-3 years. If worst comes to worst might just swap the motor.
 

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You may very well have to swap the engine to get rid of the knocking noise.
Read the trouble codes. That will hopefully give you an indication of what may be causing the idle problem.
 

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is the knock very hard to hear at idle then gets much louder at a steady rpm? a rod knock will come from the lower end of the motor and it will be heard the loudest at a certain steady rpm and the noise is very rythomatic the sound only changes with the rpms of the motor and is usually heard best around the 2000 rpm range. a rough idle could be a misfire or vacuum leak. a misfire will throw a check engine light
 

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yeah the rough idle and check engine light could definitely be because of a misfire. a lot auto parts places will read them for free unless you have or know someone with a scanner
 

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IAC goes bad on these too all the time between 70k-120k miles...from what Ive read/experienced the symptoms associated with the IAC can be all over the board. Mine didnt run right until I got a Motorcraft OEM unit, parts store units are garbage. Also COPs seem to cause a multitude of issues on these, had Accel on mine from the previous owner, I got a used set of OEM COPS and rebuilt them with new springs and boots, this solved the rest of my idle issues.

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Discussion Starter · #9 ·
looked for vacuum leak today and couldn't find anything. started my car up for the heck of it and all of a sudden the check engine light disappeared but the car still isn't idling correctly and there are no more codes don't know where to go from there.
 
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