Well, bought this truck, running wonderfully with about 123k miles, decided to do a routine tune-up.
Installed ACDelco iridium plugs, gapped to .60 but later found out they were factory gapped to .40, so fixed that. Installed new air filter, fuel filter, autolite wires.
Roughly a week later my engine light came on, and went off, then a week more and it stays on. First it was bank 1, then both days later. Same 2 codes every time 171, 174 lean both banks.
Since the code has appeared, we have inspected vacuum lines, ran fuel pressure checks, 54-55psi key on, 55-60 under load, drops momentarily below 54 from dead throttle drop. cleaned and inspected most sensors, installed a new intake gasket torqued per GM specs, inspected FPR, clean, Pulled EGR, cleaned surfaces, inspected operation, replaced gasket. Replaced MAF with rebuilt. Scantools show the MAF and O2's working correctly.
I can clear the codes, and the pendings pop up roughly 3 minutes into an idle, with the light comming on soon after.
Not long after the codes stuck, I started noticing a miss under load, usually after the truck was warm and driving steady around 30 minutes. pulled plugs, found a crack in the upper porcelain of cylinder 2, replaced with old plug I removed, week later it cracked also. Crack begins about 1/16" down from the top of insulator and stops about 1/4" from the bottom. The old plug I re-installed cracked twice, same spot, about a mm away from the 1st crack.
It's no doubt that this crack is what's causing the miss, but what's causing it to crack?
Also, any ideas on where I can go with the lean codes. I want to take it to a dealer, but if I can try something myself that I haven't already, I will.
I am driving myself crazy working on this thing. It's still new to me, so I have to get it back to working correctly. Any suggestions are appreciated!
Installed ACDelco iridium plugs, gapped to .60 but later found out they were factory gapped to .40, so fixed that. Installed new air filter, fuel filter, autolite wires.
Roughly a week later my engine light came on, and went off, then a week more and it stays on. First it was bank 1, then both days later. Same 2 codes every time 171, 174 lean both banks.
Since the code has appeared, we have inspected vacuum lines, ran fuel pressure checks, 54-55psi key on, 55-60 under load, drops momentarily below 54 from dead throttle drop. cleaned and inspected most sensors, installed a new intake gasket torqued per GM specs, inspected FPR, clean, Pulled EGR, cleaned surfaces, inspected operation, replaced gasket. Replaced MAF with rebuilt. Scantools show the MAF and O2's working correctly.
I can clear the codes, and the pendings pop up roughly 3 minutes into an idle, with the light comming on soon after.
Not long after the codes stuck, I started noticing a miss under load, usually after the truck was warm and driving steady around 30 minutes. pulled plugs, found a crack in the upper porcelain of cylinder 2, replaced with old plug I removed, week later it cracked also. Crack begins about 1/16" down from the top of insulator and stops about 1/4" from the bottom. The old plug I re-installed cracked twice, same spot, about a mm away from the 1st crack.
It's no doubt that this crack is what's causing the miss, but what's causing it to crack?
Also, any ideas on where I can go with the lean codes. I want to take it to a dealer, but if I can try something myself that I haven't already, I will.
I am driving myself crazy working on this thing. It's still new to me, so I have to get it back to working correctly. Any suggestions are appreciated!
Jan 22, 2010 at 10:32 PM
