Injector replacement

[sierra1500]

I am in the process of getting a tune from Blackbear performance. I was sent the flashscan and cable to get information from my stock set up. The scan read that my bank 2 trim levels were 16% higher than my bank one, but I had a miss on cyl #3. I replaced plugs and wires and PCV valve. The miss in #3 went away, but the DTC code of P0300 was still there. I am going to change all 8 injectors this weekend and hopefully that will cure the problem. But for some chance it doesn't cure it, what should I check next? Coils, fuel pressure regulator?:help2: :confused:

[joecar]

Sierra, welcome to the forum... :cheers: ...I sometimes miss a few threads, I do apologize.

If you still get unbalanced LTFT's, check for air leaks between heads and cats.

If you get misfires, do these things:
- change fuel filter and air filter;
- clean MAF (use MAF cleaner, not brake clean),
- do a CASE relearn (just in case you're seeing false misfires),
- ohm your plug wires while wiggling them around, they should all be close, reject the one(s) that differ significantly (but see next test),
- using a spark tester (looks like a spark plug with no ground electrode and has a grounding alligator jaw clip, available from AutoZone) test the output of each coil (should see bright fat spark),
- observe plugs/wires at night in pitch darkness, if you see corona glow or arcing, then you're losing spark strength and misfiring,
- measure fuel rail pressure with key on engine off (pressure should hold steady for a minute or so; if not then either injectors and/or regulator leak), then measure again with engine running (should be close to 58 psi and close to steady, if not then check fuel filter, regulator, pump) [AutoZone sells a $30-40 GM fuel rail compatible pressure gauge],
- check all your grounds (look also behind the LHS head, and on either side of block).

Cheers,
Joe
:cheers: