The scanner I’m using says my BLM’s are running around 108 at idle to 110 at 2500 rpm on the road. My car is a 92 Z28 with a ZZ4 350 with, Edelbrock TPI intake, SLP runners, stock throttle body, LT1 24# injectors and a set of shortly headers . The computer chip is an off the shelf part from Hypertech.

 

You're running rich and the ECM is trying to lean it out. 108 is as far as it can go. That can be caused by lots of things such as a leaking injector, vacuum leaks, saturated vapor canister, bad O2 sensor, ignition problems, etc.

 

Hypertech chips run richer then stock ones.

 

If you still have the factory memcal unit for your car, install it and see what happens to the BLMs.

The Hypertech memcal is most likely programmed for 22#/hr injectors. Having 24s in your engine would (ideally) result in BLMs at 117. The perfect BLM is 128, therefore the 108 BLM is very low and at the minimum value that you should probably attain. So as pandin said above, the Hypertech memcal is programmed to run a bit rich, putting you at 108 for the BLMs. Your car might run better with the factory memcal.

Also, do you realize that you have 16 fuel cells, not just one, and each FTC (fuel trim cell) having its unique BLM value.

How is the drivability, and how is the WOT response?

 

what exatly are the BLM's? I might buy a set of SVO ford 24# injectors, with a 2400 B&M stall for $200, the stall is brand new, and goes for $325, but I wanted to look into these 24# injectors to see if they're worth it or not, because TPIS has stated the stock 22lb/hrs are good for up to 450 hp if they're clean. Thanks for the help in advance.

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BLM- Long term adjustment of fuel in a specific cell. Lower than 128 ECM adds fuel, higher it subtracts fuel. If blm is 108 the ecm cannot take away more fuel and you will be running rich (according to your O2 sensor)

http://www.gnttype.org/techarea/faq/BLMINT.html

 

Thank Yall for the advice I will try the factory memcal when I get a chance. The car drives good. I just noticed that it didn’t have any more fuel ajustment left at idle in block 4 . And not much more at highway speeds in block 6 . As far as WOT I havn’t done much of that lately the car sits in the garage most of the time

 

It's actually the opposite.

 

Yes, blur, If the BLM value is 112 for Fuel Trim Cell (FTC) 6, for example, the ECM is taking fuel away. Baseline is 128.

EDIT: A 112 BLM value means that the ECM detected that the engine WAS running rich via feedback from the O2 sensor, and is now correcting the rich condition by taking fuel away; hence the 112 value. The air/fuel ratio should now be around 14.7:1 for that specific FTC.

BLM = Block Learn Memory; I dont know why they labeled it that, but BLM is the long term fuel adjustment; what ever it is at key off, upon the next key on, that same value is still there.

INT = Integrator; this parameter is the short term fuel adjustment factor; it is set back to 128 when the engine is shut off.

There are 16 FTCs, 0 thru 15... Each FTC has its unique BLM and INT value. At any instant in time, the ECM calculates a PW (Pulse Width) for the injectors based on several parameters, such as, MAF reading (or MAP reading), engine RPM, and air temperature. Then the ECM adds or subtracts from that PW value, the BLM and INT value for that FTC, whatever FTC the ECM is in at that instant in time. The PW is the time in milli-sec that the ECM is going to open the injectors.

Lets bring this back to the initial help question here.

Profootbrake: have you tried the factory memcal unit yet?

 

That's because your post is lacking a comma,or punctuation, so it can be read backwards, or opposite of what you mean. When I read it the 2nd or 3rd time, I realized it.

 

One more thing to watch is the "BASE PULSE CLOSED LOOP CORRECTION, SCALED 1". In TunerPro this is a finer adjustment (ALDL bit 19). It follows the O2 swings and moves up and down more quickly.

Just as a general observation with 24# injectors (ford design II) at 50# fuel pressure, I had to set the injector contant at 30# to bring the BLM's close to 128. This doesn't follow the math, about how much fuel is being delivered, should be around 28#.

The point to remember is each engine/Eprom combination can require different setttings to show the same type of output.