R 2.8 ,altitude and automatic transmissions

[jackstraw]

I posted a month back or so about my issues with my r 2.8 and my 6l80 E./2500 stall. I want to get some opinions and information about how boost is built when coupled with automatic transmission.

With stock tune ECM I experience a bottom end that stumbles and smokes until the boost gets up to minimum of about 10lb. Some where in the neighborhood of 1500 RPM. I have done the mass airflow pedal dance in my driveway at 6200 ft. and as well at the top of Berthod pass at 11200, hoping that the high elevation would be recognized and adjusted for in the calibration. Not really any better.

I have replaced the mass air flow sensor. No dice

I currently have a new EGR on the shelf as a next step. When the EGR is disconnected the majority of the problem disappears . I will say Driving with the EGR disconnected is much better but it still feels like the basic issue still exists to a much lesser degree. That gets me thinking that EGR is not the source of the issue but rather just compounds whatever issue already exists .

How can I build more boost down low and sooner? what role does the transmission have in building boost? Has anyone done a compound turbo to crisp up the bottom end.

Thanks for your input.

 

[MountainD]

Hey, G! I hoped you got that one solved by now ---sorry no one with the tune has helped you out more yet. But I definitely want to check this out as you get it dialed in! Maybe do a meet up at Cannonball or Southern Sun. Wish I could help with this one, but being a manual I don't have any experience.

 

[rocky]

If it’s black smoke, doesn’t that suggest fueling is increasing faster than the increase in air flow from the turbo, resulting in incomplete combustion and smoke?

If correct, how do you reduce fueling low down on an ECU controlled engine? Seems that’s a software issue.

 

[jackstraw]

If it’s black smoke, doesn’t that suggest fueling is increasing faster than the increase in air flow from the turbo, resulting in incomplete combustion and smoke?

If correct, how do you reduce fueling low down on an ECU controlled engine? Seems that’s a software issue.

I tend to agree a fueling issue seems like the problem, I would say that we have not seen this with manual transmissions. Likely the nature of a manual transmission get more boost sooner. I am tuning the transmission to see what works on that end . After that I may need to see if Cummins as a fix for ECU programing.