I attached a graph that shows BLMs, INT, and RPM data from my last datalog. I think overall, it looks pretty good. I was also wondering how GM normally disabled Highway mode? i thought it was through the mph enable constant. I just looked in mine, and it is set to 55 mph, and i have not touched it. If you look at the graph, you can see where my car appears to be in highway mode in the ~4000 to ~5500 sample range it leans out to 133 BLM. How much does highway mode usually lean things out?

 

I would say your BLM is not lean it is just addding fuel to arrive at stoich. sample 4200-5200 shows a cionsistent RPM and BLM with INT adding fuel around 129. If you add to your VE table there (133/128=1.04) at that rpm/map about 4% your BLm will be at 128 and you will be no richer nor no leaner as a result.

what MPH were you at in that log? I cant recall the reason GM disabled HM but it may have been to protect the cat-con.

 

When in high way mode the ECM will go open loop and disable learn. Usually setting the INT to 128 and locking the BLM where ever it is (learn is disabled). Note that the closed loop flag can stay set during highway mode. But the INT won't move and the prop gains are disabled.

The AFR is then leaned out by commanding a higher AFR. This can be a single value or from a table of values. The higher AFR creates a smaller injector PW.

RBob.

 

I am running a maf setup, so no ve tables here. Most of the log was on the highway in 5th gear doing 65mph or so.

 

Quote: I am running a maf setup, so no ve tables here.

My error. Again. I see a 1985 TPI. I should know better by now.