AC

iTrader: (3)

Thanks again everyone for all the help you give out. So I've opened my .csv files in excel and looked at the blm, afr, tps and such that was logged through C.Moates software. First off, which column of blm data am I looking at getting close to 128? Is it BLM or coarse fuel correction? Secondly, my car in closed loop under normal driving conditions here and there is right at 14.7...way to lean for me. Under boost it goes to 12.8,11.4,11.3. Do I correct the afr under normal conditions through my afpr on the intake or try and do it through the BLM's?

Dave_Jones

The first BLM column is the BLM Cell Number, it just tells you which of the 16 BLM cells (numbered 0 to 15) the ECM is using at the time.

The "BLM or Coarse Fuel Correction" is the actual BLM value, that you'll refer to to see if the ECM is adding or subtracting fuel, the goal being to see close to 128 everywhere.

The "Commanded AFR" displayed is merely a calculated value, and should NOT be assumed to be the ACTUAL AFR. (unless you're using a wideband O2 sensor, in conjunction with a special code patch that makes the WB-measure AFR value display in the "commanded AFR" field)

Later on, if you get all the fuel tables adjusted perfectly, your "commanded AFR" may equal the true AFR. But at this point, you may safely assume that is not even remotely true.

What makes you think that 14.7:1 is way too lean for you? (talking idle/light cruise here...power enrichment is another story, and the ECM has PE fuel corrections to richen the mixture when required, and you'll tune those too...but not until AFTER you've got the base fuel tables correct, IMO). There is a "730 part throttle tuning" article in the stickies that you should read.

Give some thought to buying a WB O2 sensor before you start trying to tune PE. (it also makes tuning part throttle MUCH easier, and gives you more options of how to approach things...but you can successfully tune to stoich without one, using the traditional method that we're currently discussing)

Playing with the AFPR is a waste of time, IMHO. Set it where it belongs, then leave it alone.

Also, just to make sure you're clear, you don't tune "BLMs", you tune the VE tables, at the appropriate RPM and MAP, based on the BLM you observed at that RPM and MAP. The BLM value is simply the indicator you're observing to decide if the base fuel map (i.e. VE table) requires more fuel, or less fuel.

Again, please read the Part Throttle Tuning article that I mentioned. It will explain much of this in more detail.

Also, after you've read all the $8D and '730 tuning articles, you might want to do a few searches, and read some of the posts regarding $58 code. That code (Syclone/Typhoon) is specifically designed for forced induction, whereas $8D is not. I'm not suggesting that you need to switch immediately, but it might be worth your while after you've got your feet wet a little with $8D.

HTH,