What do you do to adjust those BLMs up to 128?
My car shows around 14.5 during steady state cruising(1000rpm-3000rpm), but if my BLMs are showing rich, like the 108-115 as an example, which do you trust? And whats going on with the BLMS if they are showing that low with only .2 down from what I am commanding in the tune?
93 Y-Body LT1 big cam, long tubes etc.

 

Do 93's have one O2 sensor or two? Where is the wideband? Same pipe as the regular O2 sensor or a different side? If they're on opposite sides, then its possible you have a leaky injector or some other problem on the side with the standard O2 sensor. 14.5 with the wideband is almost perfect, but the computer is seeing slightly rich from its O2 sensor.

 

93's have two. I have two heated DENSO's. Long tube coated Stainless headers and in identical locations across from each other and no extenders. All injectors dont leak as I pulled the rail, turned ignition on, and nothing came out. They all read the same OHMS. Ran smoke in the exhaust and nothing came out of the sensors or the exhaust.
I am going to scan again and run VEMASTER after and see what happens. But I am curious as to what to do if the BLMs are showing rich, yet the LM1, properly calibrated, shows .2 down.

 

If its running C/L, you need to tune to the BLM. I'll bet your 14.7 goes rich if you lock the BLM and INT at 128 or set C/L Temp threshold to 155F. Its the ECM that is adjusting the AFR to Stoich. But its doing it from a position of the VE table being too rich. Need to lean out the VE table at the MAP/RPM points indicated if its an SD motor.

 

\Cool, I will lean it out 5% appropriately, then recheck.
Thanks

 

from my experience with a 95 lt1 (see sig) in SD mode... adding 5% (multiply by 1.05) to the VE tables was a huge jump in fueling at low rpms. it took me from 17:1AFR to 14.5AFR at idle and low rpm. Just something to go by when making coarse adjustments.

you also want to check for the split BLM issue and adjust your throttle screw untill the left and right blms match at idle

 

Sorry, I meant to say 255F for the C/L CTS Threshold.
Also when tuning C/L, it helps to shut off EGR/DFCO/Decel Enleanment/CCP that way your tuning based off VE table without modifiers.

 

Okay, I will do a 2 percent, drive it, then go further if necessary. Once this is done I will see if my WOT tables goes to where I want it, around 12.7 as it is hitting 13.2-13.5 right now.

 

When you atre checking WOT AFR, make sure your BLM is at 128 or below BEFORE you go into PE. Otherwise the ECM will ADD fuel thinking the motor is running lean. You'll chase the WOT AFR if you don't check this.

 

I will try, as I will need a co-pilot. Of course, now that I have a good power source to keep my laptop going, as battery normally lasts about 20 minutes, I can data log longer and go with longer legs to see if Long terms are getting closer to or a little below 128 once I start fixing the tunes. Here is a zipped file of my last cruise/log.
The TJ log should be richer while the other Forsteve should be a little rich.
1993 $DA2

 

Is not the LT1 BIG CAM pushing the MAP up to a RPM/MAP column that has too much fuel? IOW less vac(high map) than a stock cam at that RPM/MAP so it shows rich BLM. As Dom alluded to. Needs a tune ?