Originally Posted by
engineermike
I’ve messed with this until I was blue in the face. Basically you need fuel present and low timing for burbles. There is a minimum torque ratio set in the spark tr table for dfso. This torque ratio is generally set too high for burbles. Burble mode temporarily lowers the min tr in the right conditions and it works as intended. The problem I’ve had is that tr is used to reduce torque to whatever logic deems to be the desired deceleration torque. And if it reaches that torque before needing a very low torque ratio then it won’t command low timing because it doesn’t have to in order to reach low torque. So the next thing was to try to find a way to lower the target torque for decel, which is where I hit a roadblock. I haven’t been able to figure that out in hpt or pcmtec so I eventually brute forced it by lowering mbt in the specific load/speed/mapped point when I want the burbles to occur.