dagger1982

Have a #7 dead cylinder. Swapped plug, wire, coil pack and injector. Compression good at 150 psi. Spark is blueish, noid light has good flash on injector. Light shut off when it threw the code but came back on after a few seconds. #2 and 4 have a few misfires also for context. Throws #7 misfire code almost immediately. I have had both heads worked and new intake. Lifters and rods are new and appear to travel normally. 2012 Suburban 5.3. I am at a lose here, ready for any suggestion.

Wavelength

Maybe fuel not getting to cylinder. Have you pulled the plug and sniffed for gas?

oilcanhenry

He needs to put a OBD II scan-tool on it, IMO. He's got misfires in other cylinders as well.

dagger1982

Have gas but didn’t sniff test it. I’m using the torque pro app. Only thing I couldn’t test was a good connection to the injector. So I ordered a set of connectors. After that? Going to use my bore scope on the intake. Who knows? Maybe I sucked a rag in. Real weird one.

dagger1982

Found the problem. Both rockers were not moving with the engine at idle cover off. Pulled the head and inspected. Rods are perfect, lifter guide is good (new). Took video of cam while hand cranking and the lobes look good. The original lifters were Melling and the spring does not rotate. The new lifters are Sealed Power and the springs do rotate freely along with the internals, roller stays firm. Can’t find any reference to this online so I don’t know if this is bad or normal. Guess I will order a couple Melling lifters and see what happens. Very curious about them spinning if anyone knows.