Bog/Misfire in closed loop
06-04-2012, 10:26 PM
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Bog/Misfire in closed loop Ok fellas need some help. Driving home from work the other day the car suddenly developed a stumble/mis at low rpm and then seemed fine from about 2500 up. The longer it ran and hotter it got the more prominant the mis was. So far I've changed the o2 sensors checked plugs and wires and eliminated the MAF. Car runs fine in open loop and then once in closed loop progressively runs like more and more doodoo. Some boards say ECT. I did notice when datalogging that the ECT was reading about 40 degrees different than the gauge. My IAC counts are a little off as well. This thing has me stumped. Any help would be appreciated.
06-06-2012, 08:30 PM
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Still stumped. Changed fuel filter and ECT no help what so ever. Going to try and get my hands on a fuel pressure test gauge tomorrow. Just driving me crazy that it runs great until it's up to operating temp and then goes down hill.
06-07-2012, 07:59 AM
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Im having the exact same issue with loss of power bogging down etc. I've got a two year old built engine with less than 5000k on it. It has a new opti and ignition. After logging I was told mine is running really lean which could be an issue.
06-08-2012, 07:35 AM
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Dunno if you made any progress wih yours, I did a datalog found my map pressure is way up there meaning there's a vac leak. I'm suspecting the egr valve is stuck open.
06-08-2012, 08:24 AM
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I don't have egr any more. Did a fuel pressure test and ruled it out as it help 42 at idle and stepped to 43-44 WOT. Did find a melted 02 sensor wire. Fixed it and now I'm just waiting for good weather to put a known good sensor in and redata log.
