I have a fairly serious issue with flames out the tailpipe on decel. I played around with the factors in my ECU last year, and it improved but didn’t really get corrected. The objective is to reduce the flames enough that they won’t continue to burn my rear fascia and tail lamp.

My ECU (M2R) has 3 parameters that I can adjust:

Decel Clamp: The max reduction percentage in IJPU that’s allowed at each RPM.

Decel Decay: The decay rate of the decel enleanment at each RPM; the value is the percentage of the IJPU per engine rev.

Decel Sensitivity: The sensitivity of decel enleanment to the rate of change of efficiency at each efficiency point (MAP).

I realize that the fuel table values in the “lift throttle zones” is important too – i.e. 8K RPM and very low pressure. Is there a general procedure for tuning decel enleanment with a MoTeC?

Does anybody have a sample MAP that works well I could use as a starting point?

 

Are you getting the backfires when you're lifting between shifts or on extended decels like when engine braking down a hill? What are your Lambdas when this is happening? What is your timing? I can see .65L and still not get flames. Happened frequently when tuning out those load values.

I can tell you from experience that the decel enleanment function on my M800 was less critical than fueling or even timing during decel.

 

I get the flames during extended decels, like when I lift after a pull. My lambdas are very lean -- over 1.0 during the flame periods, which seems impossible. I'll have to check the timing in the high RPM / low MAP zone. What should it be?

 

I generally run high 30's and low 40's for timing in those areas. And my L's are in the high .8 low .9 in that area and I never get anyflames.... a few pops here and there but nothing all that big.

 

I was getting same issues and this did fix the issues well into 35deg on decel