p300

[tommypvt]

I having a bunch of misfires with my 5.3 swap. I need to get this taken care of. I am getting the most on cyl 8 and less on 5 and sometime 1 and 6. number 8 will trip the flashing ses light.

I have replaced all intake manifold gaskets. I have taken the injectors out and tested them and moved them around. Coils are moved and it still sticks to the certain cylinders. Compression is fine in the misfiring cylinders. Had someone do a hptuners crank relearn today but nothing changed.

I am not sure what is going on. It actually doesn't seem like it is missing at all. Anything else I should try? Crank Pos sensor? I am getting tired of throwing parts at this

 

[Justin S]

could be a computer tuning issue.

 

[tommypvt]

could be a computer tuning issue.

Yeah, looks like I am going to have to pick up Hptuners and dig deeper.

 

[tommypvt]

It is a Crank relearn issue. Tried to get it to relearn with hptuners but it wouldn't work. Also tried the latest snap-on scanner and it couldn't get it done ether. kept looking for full throttle. I am going to track down a tech 2 today.

 

[RichLo]

you have probably already done this but I didn't see new spark plugs in your list? Just thinking simple.

 

[tommypvt]

Yea plugs/wires are new. It needed the crank relearn. Took it to my local shop and we tried with their snap-on. It was the latest and greatest. It kept failing during the relearn. It couldn't detect full throttle for some reason.

Had to take it to a GM dealer. Much hilarity ensued but finally I was able to sit next to the second tech while he did the relearn with their tech 2 and all the fake misfires are gone. It never threw a crank relearn code but needed it.