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Discussion Starter · #1 ·
Like the title says Im having trouble with a random missfire of cylinder 3. Since its the middle cylinder on the rear bank I'd like some input on some solutions before i rip everything apart. It's my daily driver and i'll be ripping the plenum off tomorrow to inspect the plug and wire. I'm not real sure what to look for in the cap and rotor. The plugs and stuff were all replaced about 30K miles ago btw.

Anyway the symptoms are bogging down while accelerating under 50% throttle. It seems like it's only doing it when i get back into the throttle after coasting around a turn on down a hill. Maybe you guys can point me in the right direction.
 

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could be a sticking injector, when you coast the injectors are essentially off and closed. it seems like it clears itself up after a couple of seconds when you come off of the coast?

as for the cap and rotor you'll know when you look at the new one next to the old one.
 

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Yeah, I'd just replace the cap and rotor and not worry about knowing what they look like...they're cheap and really should be included in your tune up. Have you taken the car to have the codes read...that should always be your first step before tearing in to things...
 

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Discussion Starter · #4 ·
Yeah, I'd just replace the cap and rotor and not worry about knowing what they look like...they're cheap and really should be included in your tune up. Have you taken the car to have the codes read...that should always be your first step before tearing in to things...
yea i have a code reader. Bitter brings up a good possible link to my problem due to the missfire mainly occuring after coasting for an extended period. You guys think i should run some injector cleaner through it first before tearing the plenum off? and any suggested brands to go with
 

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the stuff you pour in the tank is pretty weaksauce. find a shop with an injector cleaning machine that can be ran on the car or (and this is the better way to do it) pull the injectors and send them out to be cleaned, flow tested, and balanced. i guarantee after either of those your car will feel different...as for curing the misfire...i dont know about that. it still could be a spark issue, its hard to tell when that cylinder is all the way back there.
 

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the stuff you pour in the tank is pretty weaksauce. find a shop with an injector cleaning machine that can be ran on the car or (and this is the better way to do it) pull the injectors and send them out to be cleaned, flow tested, and balanced. i guarantee after either of those your car will feel different...as for curing the misfire...i dont know about that. it still could be a spark issue, its hard to tell when that cylinder is all the way back there.
:agreed:

yea i have a code reader. Bitter brings up a good possible link to my problem due to the missfire mainly occuring after coasting for an extended period. You guys think i should run some injector cleaner through it first before tearing the plenum off? and any suggested brands to go with
Well, I take it you've used the code reader to determine you have the random misfire on cylinder #3, but posting the actual code(s) you get helps as well...:ugh2:
 

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V8 > 3G
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Discussion Starter · #7 ·
retail code readers dont give you codes for missfire. it reads this "missfire cylinder 3" and thats all. well im gonna try some fuel injector cleaner and ill let you guys know how it works
 

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retail code readers dont give you codes for missfire. it reads this "missfire cylinder 3" and thats all. well im gonna try some fuel injector cleaner and ill let you guys know how it works
It might be worth your time to run by Autozone and have them read it then just to be on the safe side...:ugh2:
 

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Discussion Starter · #9 ·
i have the same code reader as them but anyhow quick update. picked up a $3 bottle of Gumout fuel injector cleaner and just dumped it into my full tank. 20 miles later the light SES light just turned off. *knock on wood* it seems that it did the trick but i'll keep you guys posted on the results.

on a side note there seems to be an increase in throttle response and the car pulls harder up top. we'll see what happens after i run the whole tank through the car
 
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Things to look for in your cap and rotor

1. Carbon Tracking (heavy dull black lines) inside of cap
2. Burnt contacts
3. Carbon Button. check and see if its worn (should have a nice round surface)
4. Take some baby powder (idk why no one really does this anymore) and rub in on the outside/inside of your cap. It will fill in and show you any cracks on the cap. If they're severe or in mass amounts then replace the cap. IF you put the cap back on make sure to clean it.
 

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4. Take some baby powder (idk why no one really does this anymore) and rub in on the outside/inside of your cap. It will fill in and show you any cracks on the cap. If they're severe or in mass amounts then replace the cap. IF you put the cap back on make sure to clean it.
No one probably does that anymore because it's just as easy and fairly inexpensive to just replace the cap...:ugh2:
 

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I got the same problem except it was cylinder 1 misfire. I checked all the wires and changed the plugs, but nothing. good idea for the fuel injection cleaner, imma try that asap. but one quick question...did ur SES light come back on yet??
 
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