Piesta

Does anyone have this definition file for the CATS Tuner that locks the BLM's at WOT?

Thanks.

MrWillys

Definitions are only $20 from Tunercat, so why even bother asking for a file that requires a code to unlock? Contact tc@tunercat.com

Piesta

Well, I don't recall requiring a code to unlock any of my TC definitions. And yes, additional defs are approx $20 but if you look at their site, they only list $EE which includes $EEB. I know they supplied a few registered users (which I am) with the EEL def (not sure if they charged them or not). I sent an email to TC yesterday but it's a long weekend and I probably won't hear from them for a while. I have no problem paying any cost to them for the def, I'm just in a spot right now and was hoping to save some time.

Thanks for your .02

Cliff Harris

I don't understand what you're trying to accomplish. "Locks the BLMs"? When you go WOT the ECM goes into open loop mode so the BLMs are not updated. Is that locking the BLMs?

Piesta

Got it from TC, free. Their customer support is FIRST CLASS!

bjankuski

The newer EE cars 1994 -1995 LT1's will update the WOT fueling based on your long term fuel trims. If the car is adding 10% fuel at part throttle and you go to WOT it will add the 10% on top of your WOT fueling possibly creating a very rich condition. The WOT locker locks your BLM's at 128 at WOT so no additional fuel is added in at WOT besides your WOT adders. This eliminates the chance for overly rich WOT runs and allows your tune to be off slightly at part throttle.

Piesta

And when you are bracket racing this is one of several keys to consistency. Thanks for the response bjankuski.

jsiddall

Wait, I thought all PCMs used the BLM for WOT. Did that not start happening until 1994?

MrWillys

Of all the datalogs I've ever seen with 90 thru 92 speed density systems as soon as the criteria is meet for power enrichment the blm defaults to 128 and uses the VE table only. It would be my observation that modified blm's are ignored in these systems.

jsiddall

Interesting. I did some more searching on this and it seems like the best answer is some PCMs use BLMs under some circumstances.

It seems like if the BLMs are high then they are used, otherwise 128 is used.

This thread had some information:

http://forums.corvetteforum.com/c4-s...ms-at-wot.html

as did this site:

http://para.noid.org/~lj/PCM%20Tutorial/PCMtutorial.htm

MrWillys

Let me attempt to make some sense of this even if i'm almost 99% positive L98's did not use blm averages.
First, in closed loop the ecm is reading from the o2 and constantly adjusting to an afr of 14.7. Once the ecm sees a loss of vacuum greater than 91.9 kpa and a tps greater than 70% ( some tps were 50%, and this can be modified, but making the point is more important than each value) it enters into pe and ignores the o2, adds a % of fuel to the ve table the blm adjusts from and runs a much richer mixture around 12:1 afr. Rarely, would an engine see almost zero vacuum with less than 70% tps tip in to operate in closed loop at 14.7 afr for the blm to adjust to! Therefore, this is somewhat of a moot point.

The moron in the thread you posted who claimed his blm's ran high at 150 had undersized injectors, or to low of fuel pressure. Not to mention a lack of understanding of how these systems function. Blm's should always run close to 128, and being at it's programmed extremes means somethings out of tune.

It sounds like some LT1's may have this capability you mention, but as I've said it shouldn't be a factor. The narrow band o2 can be used to tune wot, but isn't completely accurate and 20 to 30% of what you see will be whacked out, but that leaves a good portion to tune to .860.

jsiddall

Here's another thread about an old TBI PCM which indicates this happens on those motors too:

http://www.fullsizechevy.com/forum/g...-i-ecm-pcm/PCM -tbi-tuning-guide.html

In PE mode: Learn is turned off and the INT is locked at 128. If the BLM is < 128 it is ignored (128 is used). If the BLM is >= 128 it is then used. The upper BLM RPM limit is only used during learn. IOW, no learning takes place above that limit (such as above 3600 RPM).

Cliff Harris

1986 Corvette. One more data point...

I noticed when I did some recent data logging that the BLM always went to 128 when it was open loop. I didn't know it did that and I always thought it used the BLMs as a basis for calculating injector pulse width.

My recollection is that the ECM considers anything over 70% TPS as WOT. I think I saw 50% mentioned in one of the links (he was guessing), but I remember 70%.

jsiddall

During your logging, do you have any idea if your BLMs were above 128 just before going open? That seems to matter.