Locking Open Loop Idle BLMs at 128?

[stew86MCSS396]

That might just crutch when Int affects changes to blm. There seems to be a lean and rich open loop parameter that ignores blm if it falls out of the range set. Suppose you could adjust those limits to “narrow” in to your target AFR.

[1project2many]

I would agree with the plan to use a 454 base calibration. I had much better luck using a 454 cal for a 250 with fuel only conversion. The engine ran even better when we enabled electronic timing control.

[lionelhutz]

I'd also agree with starting from a bin that runs open loop at idle if you want open loop at idle. There is likely some flag in the code that isn't mapped in the XDF you're using or some line of code that is different which also locks the BLM to 128 when idling.

[gpcl16]

Thanks for the advice everyone. For now raising the BLM- INT Delta seems to have solved my problem without a noticeable effect on my closed loop operation.

At some point soon, I may try starting from scratch with a 454 bin. It would take a little more work that I initially thought though because in addition to copying over my VE tables, AE, PE, etc. I'd need to go through and disable everything related to the TCC, EGR, Timing, ignoring the Knock Sensor, Disable flags so I'm not constantly setting the check engine light, etc.

[lionelhutz]

You might find it interesting to compare the 2 bins and see what comes up different that is unknown. This would tell you how much different the bins are besides the stuff mapped in the xdf you are using.

[1project2many]

I agree. We have plenty of documentation around for this ecm but there are still occassions where one can be surprised by a variable with a name that doesn't really tell you how it works.

[gpcl16]

Forgive me for being a bit of a newbie at this but how do I view the hard code of a bin to see/compare the individual lines of code? Is there a program that I can download to open them with?