2002 Silverado V6 4.3 Misfire @ Iddle

[mlevario99]

Hi, I'm helping my nephew with his truck. It is a 2002 Silverado with the V6 4.3 engine. The truck was running rough so he took it to the dealer, he took it there because he is working there (he is not a mechanic, neither am I). They plug the computer and he was told it was misfiring, so they start with the spark plugs, wires, rotor cap, but this did not solve the issue. I told him to bring it home and we can try to work on it. I have HP Tuners, so I plug the computer and cylinder 2, 4, and 6 were misfiring, with #4 the most, 1, 3, and 5 were not misfiring, this was done at idle I forgot to do it at higher RPM's.

So I went to the salvage yard and found a spider and I clean the puppets with carb cleaner and air, I only replace #2, 4, and 6, thinking that those might be the problem.

I also did a fuel pressure and it was fine, I believe near 60 psi, also did a cylinder test, 140 to 150.

So I install the #2, 4 and 6 puppets on the spider and try it again, this time, I got more misfire in #2 and #6 than before, #4 was still misfiring at idle, but when you rev the engine, I got misfiring now on #1, 2, 3, 4, and 6... #5 was not misfiring.

I also spray carb cleaner around the intake and no change in idle, so I do not think there is a leak.

At idle I removed #2 spark plug and the engine did not change, I did the same with all and the engine change when I remove #1, #3, and #5, so I guess those are the ones working.

Any ideas, could it be the spider itself?

[ironroad9c1]

intake gaskets....

[mlevario99]

If it was an intake gasket, will the engine rev when I sprayed carb cleaner? I was thinking it will.

[ironroad9c1]

Not if its sucking air from the bottom of the port and that trick hardly works