Occasional misfiring spark plugs during acceleration

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  #1  
Old 02-18-04, 07:55 PM
Spursfan
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Thumbs down Occasional misfiring spark plugs during acceleration

My Mitsubishi Galant 95 LS has had misfiring spark plugs for a short while now. These are new NGK plugs and work just fine. The plugs used to accumulate carbon but the most recent ones now show normal combustion. The car has been used mainly for short trips and I know this is a factor for the misfiring. However, since the carbon fouling stopped, the misfire only occurs when I am accelerating, and especially up a small hill near my house(it has misfired up that same hill three times now)...the car does not lose power, just misfires and the CEL comes on during acceleration. I wanted to know what you think about my remedy.
I am going to get an injector cleaner, and take the car out on a long road trip (300 miles) afterwards. The longest trip it has had in the last 4 months is 40 miles, also it is not driven often...3 or 4 times a month(Love my other car...Honda!!!). I know the carbon fouling does not happen any more...just a slight misfire up that same hill (and only at that hill, nowhere else...lol).
Billy, I see you on here....let me know if my remedy is fine and suggest anything else I should do. Thanks.
 
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  #2  
Old 02-19-04, 04:07 AM
billys68ss's Avatar
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Youve got me.... I have never heard of a misfire being partial to a particular hill... LOL. The fuel injector cleaner you speak of, is it the typr you pour in the tank? Is this the steepest hill you climb on your route? Are you sure it is a misfire and not a trans shudder or downshift? How long have the plugs been in there? Cap? Rotor? Wires?
The previous misfires, were they random or a particular cylinder? This could help narrow the problem.
Sorry I didnt get to you last night. I havent been on much lately... Lots of stuff going on here. I just buzzed through to check things out before heading to bed.
Billy
 
  #3  
Old 02-19-04, 05:04 AM
carguyinva's Avatar
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load related misfire...

...relates to secondary ignition problems. you don't mention how many miles on it or anything about previous repair history. it may well be time for a set of plug wires...or even a coil. unless you have a way of reproducing the miss at will AND something that indicates a successful ignition event, you're stuck with trial and error (parts replacement)...if the plugs are new, as you seem to indicate, stick a set of wires on it and go from there. your description doesn't sound really like an injector related misfire, altho lots of sitting and stale gas is an invitation to gummed up injectors. if the fuels smells funny, it's probably gone bad and should be run out...and since you don't drive it much, you might consider a fuel stabilizer. don't do the injector cleaner thing more than once...if a little is good, alot is NOT better in this case. let us know what you find...
 
  #4  
Old 02-19-04, 05:10 AM
Desi501's Avatar
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Re: load related misfire...

Originally posted by carguyinva
...relates to secondary ignition problems. you don't mention how many miles on it or anything about previous repair history. it may well be time for a set of plug wires...or even a coil. unless you have a way of reproducing the miss at will AND something that indicates a successful ignition event, you're stuck with trial and error (parts replacement)...if the plugs are new, as you seem to indicate, stick a set of wires on it and go from there.
I think that's right on.
 
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