BUGGERS!!!! This is not for the faint of heart!

[Shade_tree_mechanic]

Hello everyone, this is going to be a book so get your coffee, cigar,... what ever you do while reading your favorite book. This has been a 3 year battle. I have a 2001 Silverado, originally a 6.0/4L80E, of which I installed a 2004 DBW 8.1 converted to DBC. I am using a 2002 Yukon 8.1/4l80E DBW tune that I switched to DBC, and was promptly bitten by the crank sensor re-pin issue. during the initial test drive I immediately had misfire issues on #4 & #7. after changing or swapping everything that I could think of, consisting of but not limited to: coils; plug wires; plugs; intake gaskets; cam/lifters (installed stock); injectors; fuel pump; and 3 different ECU'S. I recently obtained a "known good running tune" made changes to DBC and "only" as DTC's were displayed not wanting to pollute the tune with my lack of knowledge. In this tune I have reduced knock sense on #7 to "0" and still getting the flashing CEL at moderate to normal driving. (#7) misfire 2000+ per mile.

I am concerned that #7 is getting ready to do a dance recital outside the engine soon. as such I picked up some Lucas oil treatment, switched to 15W-40 Delo diesel engine oil, today, this quieted the engine down a lot. I did forget to mention, it rattles like a diesel at idle also.

after the oil change I took a test drive, and you guessed it, "flashing" CEL !!! So in my frustration I'm like "ok (female dog), lets see if the dance recital is ready to begin!" dropped to 2nd gear, and pined the throttle. after 100 feet or so the CEL went out??? so i shifted into 3rd resumed normal driving and flashing CEL once again!!! This little fiasco can be repeated at will!

I am thinking that the timing advance tables in this "known good" tune are the culprit? but I'm still working on my first attempt at building a real tune, I have tweaked an already running tune so it could be me??

If someone will tell me what to scan, I'll get it scanned and posted.

I am just guessing at this point??? any pointers would be appreciated. I do not want anyone to solve this for me, maybe just a nudge in the right direction?

Here is the tune that is currently in the truck

2001 SILVERADO CUSTOM BUILD.101.injector.2.knock.hpt


EDIT: I am running 36# Bosch type 3 injectors at 48# of fuel pressure, the tune should reflect this.

[5FDP]

Did you do a compression and leak down test on cylinder 7 yet?

I don't see the tune being the problem, that is a very tame setup for wide open throttle fueling and overall timing curve.

If your fuel trims aren't crazy lean or crazy rich when it's not misfiring you'd think it's engine related and not tune related.

[kingtal0n]

I am just curious about the crank sensor re-pin issue, does that mean your new tune was for gen4 and the pins are different on the crank sensor from gen3?

I seem to recall something like that

I believe on Gen4 there can also be a cam sensor re-pin issue as well. Did you cover that or what happened with that?

Just curious about the wiring and hardware.

Now here is something that may help you, for diagnostics have you ever tried disabling 1 injector at a time using the scanner? This may help you eliminate issues which correspond to one specific cylinder. Do it for a while and after a while you can kind of tell how each should respond. This type of test in conjunction with leakdown and compression help us tell whether the engine has a cylinder-related issue or not.

[Shade_tree_mechanic]

yes I forgot that, compression was with in 10% no leak down test yet.

[Shade_tree_mechanic]

I am just curious about the crank sensor re-pin issue, does that mean your new tune was for gen4 and the pins are different on the crank sensor from gen3?

I seem to recall something like that

I believe on Gen4 there can also be a cam sensor re-pin issue as well. Did you cover that or what happened with that?

Just curious about the wiring and hardware.

Now here is something that may help you, for diagnostics have you ever tried disabling 1 injector at a time using the scanner? This may help you eliminate issues which correspond to one specific cylinder. Do it for a while and after a while you can kind of tell how each should respond. This type of test in conjunction with leakdown and compression help us tell whether the engine has a cylinder-related issue or not.

when LS2 came out they changed the pin out on either the cam sensor or the crank sensor, it has been 4 years since that ordeal. I don't remember exactly. It was at the sensor, wire colors changed position. this truck took 3.5 years to build, and I have been fighting the tune for 2 or 3 years since. it is a 2500 with no MPG issues, gas millage is not its strong point, LOL. and yes i have tried disabling all of the injectors 1 at a time? I am really at a loss as to where to look next. but I'll keep poking at it until I get it, or she blows up.

[kevin87turbot]

Do you feel/hear the misfire? If not, Very likely just need to perform a CASE relearn.