2012 Turbo Denali

[Redcycle13]

I need some suggestions on how to tune out a light load stumble on a 6.2 VVT engine that is completely stock other than a front mount turbo. It only stumbles under light load around 1200-1600 RPM. The AFR is close, so I doubt it's fuel related. I was thinking timing or VVT timing. Any thoughts? I can get a scan up later tonight.

[Redcycle13]

Here's a current scan with the miss. It looks to be going way rich at slight throttle movements.

[G_OCHO]

I'm new to the tuning, so take comments with a grain of salt. But maybe my comments will get the thought processes going. Looks to me your AFR are in line because of the STFTs. At stumble show rich is more than likely do to misfires on cylinders, so added unburn fuel to the exhaust. STFTs have a lot of correction so need to tune to get these within +/-2% ideal case,

[Mep_q8]

your cruise ignition timing does seem very low.. any chance of logging maf freq. With the fluctuation in the calc cylair could be a dirty maf.. maybe too much oil leaking from the turbo?

[Redcycle13]

your cruise ignition timing does seem very low.. any chance of logging maf freq. With the fluctuation in the calc cylair could be a dirty maf.. maybe too much oil leaking from the turbo?

The truck is brand new 6000 miles and only 400 on the turbo. I havent pulled the tubes to see if they are dirty, but I was leaning toward low timing and maybe improperly calibrated maf, or possible the PE table coming in way to early. Its set for like 8% throttle.

Any thoughts on this?

[Mep_q8]

post up your tune and ill take a closer look at it..

[Redcycle13]

post up your tune and ill take a closer look at it..

This is whats in the truck right now.

[Redcycle13]

Here is a scan I made today. The tune for this scan has the truck in locked open loop.

[Mep_q8]

or possible the PE table coming in way to early. Its set for like 8% throttle.

That looks to be the culprit.

Set your PE Enable MAP to 95.. and your PE enable TPS% from rpms 0-2000 at 50%.

Your logs aren't very informative. You need to log more PIDs and post up your config. I was only reading 6 available PIDs on your file to work with.

[Redcycle13]

That looks to be the culprit.

Set your PE Enable MAP to 95.. and your PE enable TPS% from rpms 0-2000 at 50%.

Your logs aren't very informative. You need to log more PIDs and post up your config. I was only reading 6 available PIDs on your file to work with.

What PIDs would you suggest logging?

[IDRIVEAG8GT]

Why not just set the PE Map enable to 97KPA, and leave TPS to 5% that way your PE table functions primarily as a BE Table.

[Redcycle13]

Why not just set the PE Map enable to 97KPA, and leave TPS to 5% that way your PE table functions primarily as a BE Table.

I guess to keep it from overfueling under 2000 RPM. If I lug the truck in high gear it will make a lttle boost under 2000 RPM, but I'm not sure if it needs 12.0 AFR. This my thoughts on why?

[Mep_q8]

Why not just set the PE Map enable to 97KPA, and leave TPS to 5% that way your PE table functions primarily as a BE Table.

turbo set ups run similar to centrifugals.. while rpm increases so does boost, and I doubt at 2000rpm any boost is being made. With heavy load on the engine and a light TPS% (eg. 25%) 95kPa could be had which would bog the motor by going into PE.

keep it in closed loop in cruise areas and open loop in boosted..

[Redcycle13]

turbo set ups run similar to centrifugals.. while rpm increases so does boost, and I doubt at 2000rpm any boost is being made. With heavy load on the engine and a light TPS% (eg. 25%) 95kPa could be had which would bog the motor by going into PE.

keep it in closed loop in cruise areas and open loop in boosted..

I'll give those sttings a try.

[IDRIVEAG8GT]

My experience is a little different, typically if you've got enough exhaust pressure at 2K to make boost, you're making torque.

And don't you dare call this raping the PE because it's not, set your PE to command around a 12.5-13.0 AFR during light load low rpm conditions that way everything is nice and consistent, and you have the correct amount of fuel to make power without bogging.

That's exactly what that table is there for.

[Redcycle13]

My experience is a little different, typically if you've got enough exhaust pressure at 2K to make boost, you're making torque.

And don't you dare call this raping the PE because it's not, set your PE to command around a 12.5-13.0 AFR during light load low rpm conditions that way everything is nice and consistent, and you have the correct amount of fuel to make power without bogging.

That's exactly what that table is there for.

That sounds like a good idea for getting part throttle low boost areas dialed in.