I'm looking at my datalog for a WOT run and would like to know if this is going leaner or reacher by reading the INT/BLM.

I have 8 samples reading 124 BLM while the TPS% increases from 65-98%, MAP is 90-94. The INT decreases from 119 to 106 through these same 8 samples. Does this indicate it is moving richer or leaner than the registered 124 BLM? I understand it is slightly rich with the 124 BLM but just trying to figure out the INT relationship.

BLM = LTFT, INT = STFT
INT<128 = Rich, INT>128 = Lean

My interpretation is; this is probably richer than 124... just hasn't had time to stabilize at this RPM for accuracy. Yea or Nea?

 

To put this clearly, the INT is removing fuel, which would indicate that the fueling during that period is a little rich. BUT! Your throttle and MAP are moving, so, AE fuel is likely being injected there in addition to the main fuel = you can't tell whether the main fuel or AE fuel is the culprit. VE is adjusted in (relatively) steady state conditions, unless you're using it to fudge over problems. VE tuning comes before AE (fine) tuning. There's no other (smart) way to do it.

 

Indeed.

Your ECM had previously "settled" on 124 for fuel trim, meaning it saw the need to regularly remove 6 "units" of fuel over time.

At the exact moment in the log you refer to, it is seeing the immediate need to remove more units (22 units). If that condition continued and the ECM saw this "need" longer, it would eventually move your BLM until the desired O2 conditions are met.

That's the short of it.

A little more information:

The INT is the derivative of the BLM.

That is to say, the INT reading is the rate of change of BLM (in a nutshell. I believe there's a bit more to the code in the way of a timer that must be set before the BLM actually changes at that rate).

That is, if the BLM is stable and should not be moving, no matter what it is currently at, the INT should hold at 128.

If the fuel needs to be added momentarily, the INT should increase. The further above 128 the INT is, the faster you'll see your BLM climb. Once the INT settles at 128 again, no more changes are needed to the BLM.

Clear as mud? =D

In any case, even with this information, its hard to say what might be affecting the INT for periods within a datalog. The ECM will see its own changes, meaning things like AE and even a mal-tuned spark table can change the fueling requirements, which might show up as brief changes in fueling requirements that are too brief to affect BLM.

M

 

Oh Great.... you guys would have to throw another variable into the mix I wasn't considering (AE)! LOL.

I've worked the SA tables already and am happy with the responsiveness and power it's now producing. Now I'm trying to nail 128/128.

I have PE disabled while I fine tweak the high RPM VE's. If I leave the AE tables alone, can't I just work the VE values at that RPM/MAP?

Mangus,
Thanks for the detailed response.