Wondering if anyone has any ideas on this?
94 Firebird w/LT4 heads/intake/hotcam just about every bolt-on.
Switched from short tube headers to long tubes. Since the header switch, the BLM doesn't activate.
BLM Boundaries
900 30
1200 50
2000 80
BLM enable temp Min 50 Max 140
Min MAP for BLM update 20
Typical MAP while cruising/maintaining speed 40-50kpa

 

are you sure your 02s are plugged in. BLMS should be constantly changing unless your 02s are toast, not plugged in , etc

 

o2s are reading properly. They sit around 450mV at around 14.7AFR on the wideband. Toggles with either rich or lean conditions
In datamaster it is going into closed loop, but if you look at the engine bits, the BLM enable is almost always reading 0 and the st and lt fuel trims are staying at 0.
In a 30 minute data run, the BLM enable only activated once or twice. Viewing the log it doesn't look like there is any reason for it to have turned on or off.

 

interesting. I've never encountered a problem like that...

 

I've come up with a possible reason for this. The ECU doesn't show any DTCs, but when I looked through the Engine Bit Display in Datamaster, it shows a bit set for 'Injector Fault Detected This Run Cycle'. The next record in the file shows the BLM disabled.
Anybody ever seen this before? I'll be running some Cleens through it tomorrow to see if that clears it up. If not, I guess it's an injector or a driver on the ECU.

 

There was a problem years ago that caused this. It would happen if you played in the target AFR tables Not sure if that is what you are getting but it sounds like it

 

I haven't touched the target AFR tables. The last log I have prior to this happening was from September. Haven't touched the tune since July. I'm kind of leaning towards a clogged or faulty injector right now. I hope it's not the ECU injector drivers.

 

What should proper BLM's look like?


Im new to the tuning

 

120-124 is what most consider perfect PCM considers 128 perfect