2004 Suburban 1500 cruise misfire

[2004BlueBurb]

Hey everybody, got an issue that's driving me nuts....My question is this, I have a 2004 Suburban 1500, 5.3L LM7 engine, 180k miles (my personal truck). Last Saturday I replaced the knock sensors due to a code set by bad bank 2 knock sensor, still had the baffles under the intake and sure enough, rear knock sensor hole has water and was rusty. Replaced both sensors with oe sensors with the harness. While I was there I replaced the valley cover gasket, cam sensor and oil pressure sensor. All went as planned, drove fine afterwards. The next day I was driving it the highway, noticed a slight misfire at cruise only, with a very slight load. Just a little bump here and there. Hooked up my scanner (Autel), #6 has 2-6 misfires randomly under light load cruise, which is 1500-2000 rpm. Swapped coils with #4, no change. Did the same with the plugs and wires, no change. Swapped injector with #2, no change. Has 140-150 psi compression. WOT has a lot of power, smooth, sometimes pings above 4500rpm, and idle are fine. Fuel trims at idle are bouncing up and down right around zero, wot they are about +4.

 

I'm at a loss of what to do next. In all the classes I've been to, whenever there is a mechanical problem, it's usually constant under load or at idle. I don't remember hearing about anything like this. Any advice would be very very much appreciated. Thank you all.

 

Tyler

[txab]

Did you use AC Delco sensors? Many have tried Bosch only to replace them because of your issue. Knock sensors MUST be torqued properly or issue may occur. Did you replace the wiring harness? Also did you use the high quality intake gaskets and follow the torque sequence and proper values?

[2004BlueBurb]

I used AC Delco knock sensors, cam sensor, oil pressure sensor, and intake gaskets. Mostly dealer stuff. Used doorman knock sensor harness. Torqued to spec, 15ft. Lbs I believe.

[2004BlueBurb]

And yes on the proper torque sequence.