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Discussion Starter #1
So I've been recently having issues with my 2006 mitsubishi eclipse 4 cylinder car. It happened out of nowhere that I started getting a rough idle. Which showed up as a misfire on cylinder 2 when I plugged in my obd2 reader. I've tried fuel injector cleaner. Higher grade gasoline, replacing the spark plug, replacing the spark plug cylinder gaskets, and valve cover gasket, I've swapped coils (stayed as misfire on cylinder 2)

Then replaced the fuel injector with a remanufactured denso. Which only seems to have made it run worse. It's not leaking fuel, and the rom jumps up and down, and it only has a rough time while sitting. (It also seems to be bucking when I drive with the new injector) so I'm really stumped. Im assuming it can only be a vacuum leak at this point, though I can't find anything. So any advice would be very appreciated.
 

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Discussion Starter #5
It was what the guys at auto zone said would work. I'll check the box for the exact branding and label. Though the spark plug didn't make it better or worse, the fuel injector is what made it worse.
 

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It was what the guys at auto zone said would work. I'll check the box for the exact branding and label. Though the spark plug didn't make it better or worse, the fuel injector is what made it worse.
Did you get a new o ring on the injector?
 

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So after clearing the codes, drive it, see what codes come back

Using live data on any generic OBD2 scanner, get the long term fuel trims
 

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Discussion Starter #9
So an update, First, the spark plug was an auto lite xp iridium. 2nd, I've disassembled everything and reinstalled the new injector making all the O rings were fine, and that everything was in place, I got everything back together, and its running a ton better. The only issue is that theres still a slight shaking at idle, and I still have a pending P0302 code.
 

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So an update, First, the spark plug was an auto lite xp iridium. 2nd, I've disassembled everything and reinstalled the new injector making all the O rings were fine, and that everything was in place, I got everything back together, and its running a ton better. The only issue is that theres still a slight shaking at idle, and I still have a pending P0302 code.
Get that autolite out of there and use the ones I mentioned
 

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Discussion Starter #11
So I replaced the spark plug with the suggested one, and its still idling a bit rough. The tail pipe makes a puttering noise from the misfire, It gets worse when coming to a stop and going in reverse.
 

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So I replaced the spark plug with the suggested one, and its still idling a bit rough. The tail pipe makes a puttering noise from the misfire, It gets worse when coming to a stop and going in reverse.
You seriously just did the 1? come on dude, you need all 4 brand new NGK Laser Iridium 3656 LZFR6AI's
 

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Discussion Starter #13
You seriously just did the 1? come on dude, you need all 4 brand new NGK Laser Iridium 3656 LZFR6AI's
Sorry took it a little to literal, my autozone carries next to nothing, so I've gotta wait for the rest to be delivered to the store. I'll get the rest swapped out and post an update.
 

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Sorry took it a little to literal, my autozone carries next to nothing, so I've gotta wait for the rest to be delivered to the store. I'll get the rest swapped out and post an update.
You never just do 1 spark plug, you do them all
Also, try swapping the coil on plug with another one to see if your misfire changes cylinders
 

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Discussion Starter #15
You never just do 1 spark plug, you do them all
Also, try swapping the coil on plug with another one to see if your misfire changes cylinders
I already tried swapping coils, cleared the code, drove around, same issues, and still P0302/ misfire cylinder 2
 

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Active, cleared and came back. And just got the rest of the spark plugs replaced. While the car itself runs better. Its still misfiring and idling rough.
Idk maybe your engine computer is blown now from the issue with the spark plug before
Maybe there’s an intake manifold leak allowing that cylinder to run lean
I really don’t know
 

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Discussion Starter #19
Idk maybe your engine computer is blown now from the issue with the spark plug before
Maybe there’s an intake manifold leak allowing that cylinder to run lean
I really don’t know
I know that theres apparently some issue from before that makes the 2006 run lean. Giving it a P0431/P0421 or something like that, that's a firmware issue that the dealership has to update, though it never caused an issue before. My next thought is maybe the EGR valve or something, considering my last options are the timing, EGR, or something failing to cause compression.
 

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I know that theres apparently some issue from before that makes the 2006 run lean. Giving it a P0431/P0421 or something like that, that's a firmware issue that the dealership has to update, though it never caused an issue before. My next thought is maybe the EGR valve or something, considering my last options are the timing, EGR, or something failing to cause compression.
The issue was the 2006 GT stock tune ran too “rich”, and it prematurely clogged the cats
 
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