2006 5.3 cylinder 1 misfire

[Rjwarfield]

I have a 2006 with the 5.3. The check engine light came on and went to auto zone and they pulled up a cylinder 1misfire code. I replaced the plugs gap at .040, replaced plug wires, cylinder 1 coil pack, cleaned throttle body and ran locus injector cleaner through it. I still have the misfire. The car runs fine until I come to a stop and then I can feel the misfire. Any ideas?

 

[rockenthebowtie]

Check compression

 

[Rjwarfield]

I forgot to say that. I had a pressure test done most of the cylinders had 160-165, cylinder 1 had 145

 

[Rjwarfield]

06 Tahoe with 5.3 cylinder 1 misfire

Update on what I have done to try to fix this misfire. I just replaced the fuel injector on cylinder 1 and still have the problem. Does it take time for the car to learn the new injector or should it run fine right of way? Thanks for any help this misfire has drove me nuts trying to fix it.

 

[Metaldrgn]

If it's the same one that came out you shouldn't have to wait for it to recalibrate.

I would recommend a leak down check to see if a lifter is failing or something or whether it's leading from the top or bottom if it actually is bad

 

[Rjwarfield]

I had a leak test done the other day and they said it was 8%. They said the test shows it's with in gm standards.

 

[Metaldrgn]

Have you cleared the code? Did it come back?

 

[Rjwarfield]

Yes I did clear the code but after driving it it came back. I switched the coil pack from cylinder 1 to cylinder 3 to make sure it wasn't the coil pack. The code still came up saying it was a misfire on cylinder 1 so I know it's not the coil pack I put on.

 

[BigWheelinBubba]

Possibly a leaking intake gasket?

 

[Rjwarfield]

Is there a way to test that?

 

[Donut Slayer]

Possibly a leaking intake gasket?

That's where I'd put my $$$$$$. The way to test it is to use a UNLIT propane torch, with the engine running, move the tip around the intake/head area. When the leak sucks in the propane, the engine will speed up. I've heard that wd-40 will work to, but have never tried that. And the leaking intake gasket is a common problem on the 5.3 motor. The updated gaskets fix the problem.

 

[Rjwarfield]

Ok, I will give that a try tomorrow. Thanks a lot this misfire is driving me crazy. I will let you know tomorrow what I find out.

 

[Rjwarfield]

Well, I tried it with brake cleaner and I did not hear any change on the misfire. If I take the car to a chevy dealer would they have a scanner that would tell me what's going on. I know the scanners that autozone uses will just tell me the code but will the higher end scanners dealer ships use tell me any thing else

 

[Rjwarfield]

Could it be a vacuum leak? If so is there a diagram showing all the vacuum lines on the 5.3?

 

[Donut Slayer]

Is brake cleaner flammable? The vacuum leak is the gasket between the head and intake. They loose seal and will suck in air and cause a Lean condition which will cause the cylinder to misfire. Ok, so a brief internet search reveals both flammable and non-flammable brake cleaner. If you used non flammable, it wouldn't change the misfire, hence the reason I use a UNLIT propane torch.

 

[Rjwarfield]

I had a mechanic put one of them high tech scanners on it and he noticed right a way the bank2 sensor 1 02 sensor is reading all over the place. The other 2 02 sensors are reading close to one an other but the bank2 sensor is not even close to the others. He said that could be my problem. Have you heard of a bad 02 sensor causing a misfire?

 

[BigWheelinBubba]

The O2's are supposed to read "all over the place". Guy sounds like he has a fancy scanner but limited knowledge of diagnosing drivability problems.

You have a misfire on cyl. #1, correct? Did you check the wire, plug and coilpack? Try swapping coilpacks from cyl. to another cyl. to see if the misfire follows the coil from #1.

If all of this checks out you may have a carbon problem or possibly a weak or broken valve spring.

 

[Rjwarfield]

I have replaced the plugs, wires, coil pack, fuel injector and the 02 sensor. The mechanic told me that the 02 sensors should be reading close to the same #s but the one was reading a lot lower then all the others. I'm taking it to a shop next week to have them look at it. I have heard a lot of people saying it could be the intake gasket.