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#1
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not the cam sonsor
I changed the cam sensor, the crank sensor, the throttle position sensor,the plugs and the mass air flow sensor. The fuel pump has good pressure. I checked the coils (cop) and cleaned every connector I could find (12). There are no fault codes at the odometer, but this SOB still has a hard hitting miss between 1000 and 2000 rpms. I've been reading about the PCM, ECM, TCM and all the other letters I could find and their prices. Any ideas about where to look next would be greatly appreciated.
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#2
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what type of vehicle are you dealing with?
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#3
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It's a 2002 Chrysler Sebring LX, with a 2.7L DOHC. It has 122,000 miles on it. Other than the miss, of course, it runs and drives great.
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#4
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Have you checked the compression? Sounds like valve related.
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#5
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I didn't check the compression, but it runs good below 1000 rpm and runs good above 2000 rpm. I will check compression and I may buy a scan tool to see if I can narrow it down. I'll let ya' know what I find. Thank you.
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#6
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I was thinking maybe funky lifter.
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#7
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put a mark on crank pulley and block and use a timing light to see if engine timing is advancing or retarding when miss starts check to see if strobe light flashes steady on light . if it flashes steady and timing advances I would rule out the electrical system .does it have a egr valve?
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#8
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Just a thought
At just under 170K I did the timing chain and guides on my 2.7 thinking that was my issue, while in there I also did a water pump. I found the timing chain wasn't the problem but that the silicone gaskets under the upper plenum had deteriorated from the engine heat and there was a vacuum leak that at engine speeds like you describe would cause a miss and stutter.
I was also fortunate and did not have one of those sludged up motors that seem to be so common and now it runs like a top again. |
#9
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I put a vacuum pump on the engine a couple different places and it held a vacuum for several minutes. The miss is hard hitting and random or sporadic. At 50 mph on a level road it feels like the firing order is getting mixed up somehow, but it's not backfiring. It's more noticeable driving, but even in PARK, it does it slightly above 2000 rpm. I'm worried that it might be the PCM.
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#10
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Another thing to check is the voltage. If the voltage regulation in the ecm is off or the alternator is going, the ignition system might suffer.
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