chasing this random multiple misfire problem....
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Driver School Candidate
Joined: Feb 2013
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From: nc
chasing this random multiple misfire problem....
i just got this car, (97 sc300, auto unfortunately) and it has several codes. just trying to get it to pass inspection for now. had codes for insufficient egr flow, the guy i got it from already put a new egr valve and temp sensor, so i just wired in the resistor to make the code go away. one of the o2's was dead so i replaced that today. vss code, have to order a sensor. and the random multiple misfire and misfire on cyl 1 and 6.
i thought maybe the o2 would fix the misfire. the guy had already replaced the plugs, wires, dist cap. i ran a bottle of seafoam through an i.v. bottle and made it run a little better but no change in misfire. there are no symptoms of a misfire at all, the car runs great. i was thinking next to replace the crank position sensor but i have to order it and will be several days.
what else can i check for this misfire problem??? could a stuck or clogged egr still cause this even with the resistor wired into the temp sensor? im getting very annoyed with this thing already.
i thought maybe the o2 would fix the misfire. the guy had already replaced the plugs, wires, dist cap. i ran a bottle of seafoam through an i.v. bottle and made it run a little better but no change in misfire. there are no symptoms of a misfire at all, the car runs great. i was thinking next to replace the crank position sensor but i have to order it and will be several days.
what else can i check for this misfire problem??? could a stuck or clogged egr still cause this even with the resistor wired into the temp sensor? im getting very annoyed with this thing already.
Driver School Candidate
Joined: Feb 2013
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From: Tn
couple of things I would suggest: 1. connect a computer to it and look at the readings on all the sensors one by one. If you find nothing there, you may want to look at the cars ECM. this may be the problem if the car runs fine and your just getting a bunch of false readings. let me know how it turns out.
good luck
good luck
Thread Starter
Driver School Candidate
Joined: Feb 2013
Posts: 17
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From: nc
yeah ive got a scanner where i can look at all the sensors, but dont know the specs. going to look them all up tomorrow at work and check them out. also i havnt checked the ignition timing, since the guy i got it from replaced those ignition parts i have no idea what he took off and maybe put back wrong, he said he didnt really work on cars so...who knows.
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Joined: Feb 2013
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From: nc
also going to run some more seafoam through tomorrow and some fuel additive stuff to clean it out some more. i love driving it and really dont want to park it and tear it apart just yet. will go ahead and order the crank sensor since i know that can be a culprit in random misfires and get the vss squared away.
Thread Starter
Driver School Candidate
Joined: Feb 2013
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From: nc
just checked a couple things. long term fuel trim is positive and staying there so its definitely running lean which can cause the random misfire. maf is working correctly at .50. ign timing is around 18 degrees at operating temp so that is def. not right. supposed to be around 10? or should be set at 10? o2's are working correctly now. i dont have any tools with me at the moment so i cant reset the ign timing. when i got the car it was noticeably pinging at initial rev so i retarded the ign timing a little until it stopped, i dont know how much i did, but just did it to drive safely until i can check it.
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