Knight94

Ok so here goes. This website is really awesome and I love searching on the information, but I cannot seem to find my answer to this question.
Running 355, mild cam, 24lb injectors, Edelbrock Intake and Headers.

When I am at idle, my WB shows that I am around 14.3 to 15.4. and my BLM's in cell 0 seam to be INT 129 and BLM 127. But when I am at cruising speeds. 55 to 70 I jump to Cell 14 and my INT is 126 and BLM is 108. This also does this in cell 10. Most of the other cells that I have jumped to to not do this. They lower some but around 124 to 126, which I am content with.

So what I have done. Well most of the people and searching have pointed me to pulling Grams in my MAF tables. Which I have done, and hasn't helped. No matter how low I go in that particular grams, It shows rich. I have not gone extreme by going below other grams in previous or current tables. Not sure if I can, because wouldn't that confuse the computer by showing it twice?

So my question is, Is there a way to just reduce the fuel amount in a particular cell (like 14)?

I also have tried reducing spark advance as well.

Also no matter how long I stay in say Cell 14, my INT will always be around 124 which I am happy with, but the BLM's are always at 108. My understanding is even after a while of being in that particular cell the INT would try to meet the BLM. But even after 5miles on a nice straight level stretch of road the INT does not move.

Also, my WB is showing 15.4 at cruise speed.

So how do I, or do I need to correct this? My reading is telling me I always need to get close to 128/128. But wouldn't my WB be running leaner than it already is?

Has anyone run into this?

Thanks for your time.

tequilaboy

Are you using a $6E bin with highway mode fuel enabled?

If so, this may be part of the problem. I assume that you are running in closed loop mode with an 86-89 MAF bin. Would be helpful to know which BCC or mask you are using as a base.

Suspect that a combination of old SAM cell data and disabled learn control under some conditions is interfering with normal BLM update behavior.

There are 2 SAM (stay alive memory) cells. SAM cells A and B. These are used to retain historic BLM values between ignition cycles. Most MAF bins will store the BLM value from Cell 0 into SAM cell A, and the BLM value from cell 10 into SAM cell B. This is assuming min/max coolant temperature and limit conditions are fulfilled. SAM cells are typically limited from 118-150, but your bin may have been modified to allow the 108 lower limit.

Side note: If running a low temperature thermostat and more aggressive fan control, you may not be fulfilling the conditions to ever update the SAM cells with valid data. They may be holding very old values as a result. Most forget about or are unaware of the need to correct the SAM cell temperature limits when changing t-stats and fan on/off temperatures.

On the next ignition cycle, cell 0 will be populated with the stored data from SAM cell A. All other cells (1-15) are populated with the stored data from SAM cell B (which comes from cell 10).

These BLM values will remain constant until learn control is enabled and the INT actively drives the BLM up or down in each cell as required.

I suspect you somehow have 108 stored in SAM cell B. I also suspect that learn control is disabled due to running conditions while in cells 10 and 14 that is preventing the BLM from being updated normally in response to the INT, perhaps due to highway mode fuel being active with a leaner than stoich AFR target.

Disconnect battery or ecm power to clear the SAM cells and reset them to 128 to rule this out as a source of error. This will allow your BLM values to start fresh from 128 in each cell.

Disable highway mode fuel if enabled to avoid interference.

If the INT continues to drive the BLM down to 108 in cells 10 and 14, then you are really running rich in the corresponding airflow region (typically 22-34 gms/sec and above 34 grams per second). Other cells with similar airflow like 11 and 15 should also be affected.

If this is the case, reduce the appropriate MAF table values in the affected flow region to lean out the calibration and bring the BLMS back up into the middle of the range.

Knight94

Tequilaboy,

Thanks for the info. I am still a newbie to all this so I am trying to learn. What you stated about SAM A and B makes sense.

I am running ARAP.bin in $6e. Adjusted injector constant for 24lb. I have been scaling down the Maf tables in 2 and 3 by several grams, but the BLM is still at 108. I will be doing more testing tomorrow and try some more adjusting.

Now am I understanding you correctly that just by disconnecting the battery, It should default the SAM cells to 128?

I will keep you posted on my findings.
Thank you,

Knight94

Ok. So I finally have gotten my BLM's where I want them by using the MAF tables. Depending on the cells they are + or - 5 from 128. So I am happy with that. Just took a lot of tweaking. Also. I spent all day working on it when I was having the BLM's at 108. Let everything reset overnight and was able to see it pul up to 122 and then worked from there.

Now I am just working on my open loop section. Time for a new post.