850 is way to high for idle at temp, that's why the MAF is at 10 and 11g/s
you need to figure out why the idle is so high, something else is going on other then the MAF.
the set idle is around 550 rpm's with a MAF reading around 6 g/s

Neal

 

your truck is adding more fuel over what the VE table is telling it that it needs on bank 1 (drivers side) while bank 2 is not adding at idle.
possible injector issues or air leaks,
See if you can log the throttle position and spark timing with it idling and warmed up.
you don't typically see high idle from a truck with an electronic throttle

Neal

 

Would that be timing advance for cylinder 1 and absolute throttle position I have these on BD

What am I looking for on this

 

Yes, use those PIDs
looking to see if these parameters are within reason and looking for a reason the idle rpm's are so high at idle
its possible the TPS has an issue and is causing the high idle
does the truck have any current trouble codes?

Neal

 

I would look for throttle positions in the 12 to 20% range at idle and timing in the 16* range. You also want to slowly advance the throttle and watch the output of the TPS on bluedriver to see if its transitions smoothly.

Neal

 

i still beleive your MAF sensor reading is double of what you should be seeing of about 6g/s at idle for a 6.0 / 6.2 liter engine at sea level. it can not suck twice as much air as its displacement on a stock engine unless you have a 12 liter engine or some very efficent induction like blower or turbo.
you can read here on all data https://www.alldata.com/sites/defaul...0engine%20size.

 

I do have a Delphi MAF coming tomorrow and that will be my last shot at a new sensor.

The timing advance stays at 26 when at idle warm or cold, and the tps doesn't seem to jump wildly as I increase the gas pedal , I have a few pics going from cold idle to 2500 rpm , 2500 rpm starts CEL flashing.
I don't get any solid CEL but can go and scan and still find errors.

If I add the new MAF tomorrow is there a strict procedure, I have been unplugging battery negative , instal maf , reattach battery , turn to on and read and clear any codes, do I need to drive on the highway or for a period of time ?

 

Would the fact that the engine was rebuilt and has an aftermarket cam make a difference on the idle? I guess it was done long ago as the owner gave a list of things done. He said the engine was good but I guess the guy was mechanic and decided to just make these upgrades. The last owner and we've never had the CEL flashing ussue until now and we're on a year of owning it.

Recently had the engine rebuilt with the following
upgrades:
Elgin E-1840-P Cam
LS7 lifters
New Valve springs
New Pushrods
Melling Oil Pump
New cam, rod & main bearings

 

Yes it makes a difference, that cam required custom tuning.
The higher idle and the MAF readings make sense now, along with the higher timing.
That's an aggressive cam for a hummer unless it has other performance items like headers, stall convertor, rear gears and a good bit of tuning
It should have a choppy idle also, but with the idle at 850 it may not
Your MAF readings will not be as stated for a stock engine, in the 6 to 7 g/s at idle, they should be in the 10 to 12 g/s range as they are with that cam shaft.
you ECT is low unless the truck was not fully warmed up when you took the screen shots.
I would have a crank variation relearn done first and see if this will stop the flashing CEL,
I think you may have other issues also based on the long term fuel trims but its not so far out that it would cause the flashing CEL in my opinion

Neal.

 

Yeah when we first went to look at the hummer I thought there was a problem with the engine but had to google the cam and see thats what it sounds like.
but there's definitely a real ruff idle now , like shaking on the wheel and seats sometimes and a ruff start and need to give it gas sometimes to get going . I might grab a xtool a30m i saw on amazon for $ 200 cad its bi directionall.

You think the tps and timing advance are within range. ?

Appreciate all the help.