misfire help please
Burning Brakes
Joined: Jun 2016
Posts: 761
Likes: 66
From: Fitzwilliam New Hampshire
Try to keep wires away from each other and away from any grounding metal with plastic wire looms and wireties, so wires do not touch each other or ground out on motor or exhaust manifolds.
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Intermediate
Joined: May 2017
Posts: 26
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From: Hendersonville North Carolina
that has already been done. i used the original wire looms in the car and zip tied them from being near any metal or hot surfaces. Thanks for the explanation.
Le Mans Master
Joined: Jul 2004
Posts: 6,215
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From: Clifton Park, NY ............Clearwater, FL ... 85 Original Owner
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Intermediate
Joined: May 2017
Posts: 26
Likes: 0
From: Hendersonville North Carolina
Le Mans Master
Joined: Jul 2004
Posts: 6,215
Likes: 694
From: Clifton Park, NY ............Clearwater, FL ... 85 Original Owner
Le Mans Master
Joined: Aug 2015
Posts: 6,082
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From: St. Charles MO
I know you said you recently replaced the plugs, and they were pre-gapped. I would suggest going back and gapping them yourself at 0.035" instead of the larger specific gap. That is plenty of gap to ignite the mixture, and will make it easier for the spark to arc across that gap instead of where you don't want it to arc.
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Thread Starter
Intermediate
Joined: May 2017
Posts: 26
Likes: 0
From: Hendersonville North Carolina
I know you said you recently replaced the plugs, and they were pre-gapped. I would suggest going back and gapping them yourself at 0.035" instead of the larger specific gap. That is plenty of gap to ignite the mixture, and will make it easier for the spark to arc across that gap instead of where you don't want it to arc.
Thread Starter
Intermediate
Joined: May 2017
Posts: 26
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From: Hendersonville North Carolina
good idea, since I'm pulling the plugs anyway might as well check to see. I wouldn't think it's that because it so subtle but it's always good to eliminate that from the equation. Waiting on some parts and will update in a couple days
Instructor
Joined: Feb 2015
Posts: 234
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From: Stuart Florida
I was just thinking of the mechanism of gas getting into oil. Through the rings is a prime candidate. I would think this would give you low compression or at least it would show up on leak-down test. Of course there are other causes of bad compression test, such as bad valves. This may have nothing to do with the miss. It's just that gas in the oil can wipe out parts such as bearings so you will want to track this down if it persists.
Race Director
Joined: Apr 2002
Posts: 10,036
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From: Anaheim CA
I think you have a ruptured fuel pressure regulator diaphragm. That will allow fuel to go into the plenum. It then runs down the runners and into the cylinders. From there it works it's way around the rings and into the oil.
Thread Starter
Intermediate
Joined: May 2017
Posts: 26
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From: Hendersonville North Carolina
that has already been changed. Thanks for the siggestion
Thread Starter
Intermediate
Joined: May 2017
Posts: 26
Likes: 0
From: Hendersonville North Carolina
UPDATE. Changed plugs and wires again. check gap on old plugs all but one was .5 the other being .6. thought that might of been the issue but miss is still there. Compression check was done also and everything was within specs. lowest reading was 190 the highest being 207. all other were around 205. barely within specs but still within 10%. i could not get a check on cylinder 8 (passenger back plug). I went with Taylor wires this time.
so this is where i stand. still with a slight stumble/misfire. i drove it over the weekend and going to check over everything today. what about the PCV? would this cause these issues also?
so this is where i stand. still with a slight stumble/misfire. i drove it over the weekend and going to check over everything today. what about the PCV? would this cause these issues also?