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Discussion Starter #1
I began to have problems with my car since I had the dual exhaust installed. Whenever I have the car in park for longer than 2 minutes the RPM drop to 500 for a second then return to 750, it continues to do so for as longer as the car is on. The same thing happens when I come to stop when I am driving. I had the battery, alternator, spark plugs, and the air intake checked and none of these seem to cause the problems. I had auto zone run the test on the computer an no codes came up. I am thinking it might be the oxygen sensor.
 

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yeah, i think the welder got a little too close to the O2 sensor and one may be burnt out. I would just either take it to autozone to tell them which one is bad, or just buy a new set and replace the pair yourself.
 

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I kinda doubt its your 02 sensors. When they trip, it trips a CEL.
I would test them with a multimeter, or have someone test them for you.
Did you ever get a check engine light. You could haev an exhaust leak somewhere.. or even a vacumm leak.
 

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they dont always throw a code. if there is a small short that sometimes works and sometimes doesnt, it wont throw a code. he is saying that it works for about 2min before it kinda flucuates for a second. that split second wouldnt be long enough for the CEL to go on.

vacuum leak would hold the idle high. trust me, ive had about 5 of them, and can be in excess of 1000-1500rpm at idle
 

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It might be the O2 sensor but it might be the Idle sensor causing the fluctuation. But Monkey is right O2 sensors can be intermitten and unless they come on the computer will not store a code.
 

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Discussion Starter #7
I took it the muffler shop a day after I got it installed and they said there wasn't any leaks. I recondition Mac filter about a month before the mufflers were installed. I quess I'll have the oxygen sensor checked.
 

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Discussion Starter #11
I took everyones advice on what was causing the problem, but nothing helped. My engine light doesn't turn on so I don't think it's the O2 sensor. I don't know if you have the same problem, but when I press on the brake I notice the rpm drop. Check out the discussion on the same subject:


http://www.v6stangs.com/forum/viewtopic.php?t=2616
 

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this has been discussed a thousand times. mine does the same thing with the stock exhaust. my guess is it's a coincidence with the exhaust and the real cause is the fuel delivery system. you didn't say what year car you had, but many people have this problem with 99 and newer cars.
 

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Discussion Starter #14
I have a 2000 and I have pretty much given up. When I have enough money I'll take it to ford and hopefully they'll find the problem.
 

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Discussion Starter #16
I went back to the muffler shop the day after I had the exhaust installed and they found nothing wrong. If anyones finds a solution please let me know.
 

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Discussion Starter #18
No I haven't tested them because no codes come up and the engine light doesn't turn on.
 
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