Misfire 3rd Cylinder

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MatthewDavid

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ok I got all the water out of my spark plug wells... totally bone dry... and all my coils are working... would the IAC valve cause a misfire?... I scanned it and it says misfire on cyl 3... but it works if you change it it fires just the same... but it makes my engine shake a lot... how would the IAC affect this?... could it be the spark plug?... but they're new... maybe gapped wrong?... the store said .54 but you guys say more around .4...
 
Shoulda put this in your other thread so it's easier to see what's been done.

After scanning it did you clear the codes? If so, did it come back or is this code the old stored one?
 
No, the IAC would not cause a mis-fire on a certain cylinder, the vehicle would just run rough.

This is a Gen 2, right? How are the connectors to the cops, are they wet? Did you actually remove the entire cop and boot? Since changing cops around results in #3 still mis-firing, I suppose the cops are ok.
 
Yeah it's a gen two... and I have changed them around a few times... I got all new boots... everything's dry... took it to a shop to have them check it too... they couldn't figure out what's wrong.... you pull it and then it works fine... you put it back in and it'll run perfect for like an hour then it starts running really rough again... I might put one of the new COPs I got in that cylinder and see if it moves again...
 
Only thing I would say is make sure the electrical connector for the COP is seated right, no bent pins, etc.
 
Alright went through and made sure everything's good... I swapped the coil out for a new one that I had in a different cylinder... still runs kinda rough... I'm sure all the coils are good... there's a spark comming from it for sure you can hear it and if I disconnect it while it runs it changes a lot... but what would cause it to run so rough... it's baffling cause like a week ago it was running perfect... haven't got the new codes yet... haven't gotten a chance to drive it far enough ... it snowed last night so I don't know... could the wires have anything to do with it? if so how hard are they to change?
 
You are doing everything right, but getting the codes pulled is something that should of been done first. Once the codes are pulled, you can get a better understanding what is the issue and what needs to be done. I believe you can rent the scanner at any auto store. If you have a second car just take a trip and borrow the scanner.
 
I already scanned it twice... both times it came up misfire on cylinder 3 so I'm wondering what all can cause a misfire?... it's running ok... got good power... it just doesn't all the time... it chugs at stops and then runs ok... doesn't make sense
 
They're all new plugs... Autolite platinums... but I did wonder about the gap... they told me .54 and on here everyone recommends .4... doubt that would do it though.
 
Sounds like it could be a 'duff' plug. Have you tried switching the plug with one from another cylinder? I would give that a try next.
 
Hehe... Im thinking (hoping) you meant 0.054'' right? Heck, would it even be possible to open a plug to over 1/2''?
 
you wouldnt be able to gap a plug to .54 so dont worry about it. thats not it.

you swapped the coil to another cyl and the miss is still on cyl 3 so that rules out the plug. bad plug is a possibility. ive seen a few cars come into the shop with fresh autolites and a misfire due to the plugs (though bosch and champion are far more common to be bad) when you swapped the coils and the miss stayed on 3 you should have swapped the plug to a different cyl. that would let you know. if it still stays on 3 you either have an injector problem or base engine concern.
 
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