I have been tuning with the BLM's and was wondering if there is any reason or benefit to change the "BLM Update Rate" or "BLM Update Cell Amount" in TC so that I can get more BLM fluctuation while I drive. With my scanner I can only capture so many frames and it seems like the BLMS don't move much between cells as to where the INT are back and forth. As soon as I get the BLM's close I will try the locked BLM trick and go off of INT value.

 

To make tuning a GMECM easier, follow these steps.

One way is to make the system run in 2 Block Learn cells instead of the normal 16 cells. This gives you the advantage of the ECM "learning in" a Block Learn value instead of jumping to the next cell just before you're ready.

To do this just put the max values in the BLM mid and high cells for map and rpm. This will give you an "idle" cell below 900 RPM and one cell for everything else. No more jumping cells.
REMEMBER: Restore your Block Learn Cells when you are finished tuning!

Another way is to speed up the Block Learn process.
Decrease the update rate. Don't go below about 4 (decimal) or your BLM values will start following the integrator all over the place.

The math is:
Frequency of BLM update (msec) = (Bin value + 1) * 50
(4 +1) *50 = 250 msec between adjustments.

REMEMBER: The Block Learn values are your indicator of how much error is in your Volumetric Efficiency table. If Block Learn is at 128 everything is just right. If your integrator is more that 3 clicks away from 128, the Block Learn value is still "learning". I consider a well tuned motor to have Block Learn values between 134 & 122. Not every motor can achieve this though.

Example:
Block Learn is 140. Integrator is 127
140/128 = 1.09 or 9% lean.

Adjust the VE table up about 5% (so you don't overshoot) and do the next point. I usually use about 1/2 the correction (BLM) value to adjust the VE tables to prevent overshoot/undershoot problems. Saves wear & tear on the PROM burner too..

 

So I need to set the value in the low cell to 900 instead of 700 and set the mid and high to 6375 RPM? And set the Map boundries to 100 on the mid and high and what do I set the MAP boundry low cell to? Also, you said don't go below about 4 in the update rate but mine was set at 2.4 sec to begin with, is this wrong?

 

"So I need to set the value in the low cell to 900 instead of 700 and set the mid and high to 6375 RPM? And set the Map boundries to 100 on the mid and high and what do I set the MAP boundry low cell to?"

Set the rpm low cell 200 above where your idle rpm runs at. This way the lower idle cell will be within idle rpm range. Otherwise you run the risk of making it one cell learning.

Set the map lower cell to 17-20. Make sure your idle kpa is under that value also.


"Also, you said don't go below about 4 in the update rate but mine was set at 2.4 sec to begin with, is this wrong?"

The 4 in the update I refer to comes from the actual hex value in that location. Because I don't know what ecm you are using, I can't give you the location to change in a hex editor. I gave the math that covers a lot of ecms. If your value in tunercat is telling you 2.4 seconds, that is very long. The 4 would give you a 250 msec update rate (.250 secs). Set the tunercat value between .400 and .250

Did I clear this up for you?

 

I think I got it now. I am running the 730 ecm too. I will try the .250 sec update rate and go from there. Thanks!