MAF Timing LB7

[LB72004]

I myslef personally do not see any reason as to why you would need to change this. It is pretty easy to set up a timing table to allow for good milage(high timing in the cruise area), and then set it up for fast turbo spool(moderate timing in teh low RPM power areas). I just don't see any advantage to setting it up so as to change timing tables based on MAF flow. I know I have played quite a bit with timing, and found with the LB7's larger injectors they don't take as well to really high timing at lower RPM's like the LLY+ does(I saw a drop in milage at more than about 6.5 degrees of cruise timing whereas the LLY guys will go up to around 8-10 at cruise). And I have found that a little more timing over stock helped my spool up some. Also just because the option is there to change timing, it doesn't mean the rest of teh code in the ECM will fully support the changes. There is alot in the ECM we cannot see, so like you posted above there could very well be some other hidden tables that need to be opened up to get this to work. Then again, if they open the tables who is to say it will be beneficial. I know i for one like teh MAP based timing as I have been up in altitude ab it and found it to work quite nice with the changed timing at altitude.

thanks for the reply. that makes sense. that's pretty much how i have had my timing when on MAP. with no real data other then how it feels, it seems that when i lower the timing i get faster spooling. let say i am cruising down the highway at 2000 RPMs and 20 MM3. now if i wanted to pass someone driving slow then i press on the accelerator. in a second or two the turbo spools up and i get the power to pass. now if i lower the timing in the higher MM3 areas of the 2000+ RPM band it may spool in one second or less creating a more responsive truck (which is more fun to drive). now lets say i am towing and the RPMs are sitting in the 2000+ range and timing is set too low (for quick spool) then the MPGs go out the window and the EGT go through the roof.

now i know there is a line between the two where one can get both to work, i was just hoping that this would produce a better system.

it doesn't mean the rest of teh code in the ECM will fully support the changes.

i was kind if hoping this wasn't the case. if it is, wouldn't one think that this option would not be available? but what do i know? i not a programmer. i guess the EFI live programmers (Ross???) would be the only ones to be able to confirm this

and another question... when the timing is based on the MAP (baro) sensor is it only set on startup or is the ECM constantly monitoring the sensor and adjusting as necessary? example: driving from low altitude to a high altitude, the ECM would start out using timing table C but as one climbed up the mountain would the ECM switch over to the other tables B or A? or would this only happen if the engine was restarted. and what about the reverse? coming down from a high altitude, would the ECM still use table A/B until the engine was shut off?

i know that this may not help get the problem resolved but if(or when) i end up going back to MAP timing then it would be nice to know that the ECM is taking care of the baro timing selection properly