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2007 Chevrolet impala ls 3.5l v6
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Discussion Starter · #1 ·
I have the good ol 3.5 and I'm Getting heavy missfire counts from cylinder 5 and 6 and a couple from 1 and 4. I've changed all the injectors and put new plugs on 5 and 6 to see if it fixed the problem.. it didnt. All wires are new. Intake manifold gaskets are new......I'm at a loss here. It doesn't feel like a dead miss.
 

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Can you explain?
ICM is probably integrated with the coils unit. So not something that can be changed separately. Makes it expensive to use the "shot gunning" approach. Maybe get one from a junkyard to try and see if it changes the misfire behavior. Once upon a time all these components were separate. Even the coil pairs could be swapped out separately.

You mentioned P1174. Check that the fuel pressure regulator is not leaking fuel through the vacuum port directly into the intake manifold. Pull the vacuum line from the FPR. If wet with fuel, replace FPR.
 

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2007 Chevrolet impala ls 3.5l v6
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Discussion Starter · #7 ·
I've got a 3.5 I think you're describing the 3800 style impala. I compared spark plugs and cylinder 5 was actually the wrong one it was shorter. But my question is can that make cylinder 6 missfire too
 

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I've got a 3.5 I think you're describing the 3800 style impala. I compared spark plugs and cylinder 5 was actually the wrong one it was shorter. But my question is can that make cylinder 6 missfire too
Believe they all have coils, ICM and FPR. The configuration may vary but those are some likely candidates for your symptoms that should be checked.

As for wrong #5 plug making #6 misfire. Probably not unless it messes up the ICM somehow.
 
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