BLM kinda high or ok??

[Buix893]

When I start the car its at 128...then after 5 minutes is at 138, then after being fully warmed its at 132-136. Is that ok??...I know it should be at 128, I checked the plugs and they are fine, and FP is at 44psi with line off as usual.

Could it be a vaccum leak??? My boost gauge is rock solid on about 15vac and has always been, and that's fine, but just wana know what you guys think...:biggrin:

 

[NorEaster]

What I have found

When I start the car its at 128...then after 5 minutes is at 138, then after being fully warmed its at 132-136. Is that ok??...I know it should be at 128, I checked the plugs and they are fine, and FP is at 44psi with line off as usual.

Could it be a vaccum leak??? My boost gauge is rock solid on about 15vac and has always been, and that's fine, but just wana know what you guys think...:biggrin:

I have been chasing down high BLM's (150=pegged) for a bit and from what I have found, people are saying 128 +/- 10, so you are within the range.

 

[TurboDave]

I have been chasing down high BLM's (150=pegged) for a bit and from what I have found, people are saying 128 +/- 10, so you are within the range.

Your BLM's are fine, as long as the car is running good don't worry about them. They are well withing their operating range and are doing what they're there for.
Not to worry unless they're pegged high or low.

 

[mikestertwo]

Guys worry too much about their BLMs. They don't have to be 128. That is just the center of the adjustment operating range. As stated above 128 +/- 10 is ok.

 

[stock84GN]

what are BLM's Thanks

 

[neilb]

what are BLM's Thanks

BLM stands for "Block Learn Multiplier" (or Long term fuel trims). It is part of the Fuel trim program your ECM uses for self tuning. It is used with the INT (Integrator, or Short term fuel trims). The integrator controls the injector pulse width according to the signals from the O2 sensor (rich/lean). It has a scale that it follows where "128" is perfect Air/fuel ratio (in the perfect world) The integrator constantly is following the O2 voltages (going up and down). The BLM is kinda like the big boss in a way. It only moves when it has too: the Integrator has moved beyond a set parameter and can no longer keep the engine in proper fuel control. This sort of sets a new "page" of fuel trims for the Integrator to follow. If the BLM moves it means there has been a "trend" set where for a certain period of time the integrator has been trying to correct a rich or lean bias. In the perfect world both BLM and the INT would be steady at 128 or 0% (in OBDII) but some minimal movement is normal in the real world.

This is the best way I can describe it, Others here might have a better way of explaining it.

 

[Buix893]

Block Learn is a fuel adjustment that the ECM see's to try and keep Air/Fuel at a steady stance....Yea what he said above....lol

 

[GNRick]

On my 86 GN that just turned 26k miles, blm=140. I hooked up my home made boost leak detector and I can hear the air escaping but can't pin point the location. I sprayed the intake with soapy water but still can't find the leak. I suspect maybe the egr valve. Anyway I will have to bring it in to get it smoked. So in my opinion, 140=leak. BLM stays at 140, doesn't go higher or lower than that. Very frustrating.