Scantool?

[thedave1164]

Have you done lower intake gaskets on that yet? If you get ahold of a scan too look at your long term and short term fuel trims(I forget which one it is) the lower intake gaskets are extremely common on that and cuse it to run lean. Easy repair too

yeah, the Gaskets were done shortly after we bought the truck, and we tested for it twice now.

the one time I had someone scan the system, it was having misfires on 1 and 8, he determined from that and others diags that it was most likely the fuel injectors, I ordered a set and put them in.

the P0300 code cleared after, until my wife was driving home yesterday, then it popped up along with running rough, then ran smooth again before she got home.

So I need to be able to look at what cylinders are misfiring now to determine the next course of action.

[SouthPaw]

Coils, plugs and wires good? I think that year of GM had individual coils per cylinder.

I had a 2005 Silverado 1500 with the 5.3L that had an intermittent misfire. Changed the coil on the one cylinder and all new wires, never had another issue at 130K when I sold the truck.

[thedave1164]

Coils, plugs and wires good? I think that year of GM had individual coils per cylinder.

I had a 2005 Silverado 1500 with the 5.3L that had an intermittent misfire. Changed the coil on the one cylinder and all new wires, never had another issue at 130K when I sold the truck.

Checked the coils, they appear to be good, wires are newish as are the plugs

[SouthPaw]

How many miles on the old girl? Not to scare you off but we used to see random miss fires on small head gasket leaks. Some shops have a ‘sniffer’ that can sniff out exhaust gases in the coolant system.

[thedave1164]

How many miles on the old girl? Not to scare you off but we used to see random miss fires on small head gasket leaks. Some shops have a ‘sniffer’ that can sniff out exhaust gases in the coolant system.

About 120k