I was pondering something relating to a BLM lock...
First off, let me say that I've only dabbled a small amount with chip programming, so at best I'm way down on the steep part of the learning curve. So I may have a fundamental misunderstanding here.
That being said, as I understand it (from Carls excellent explanations over the years), the WOT BLM is part of the final inj pw calculation. If you change the BLM by 5%, then the amount fuel the ecm wants to inject also changes by 5%. Yes?
Now suppose you get your chip perfectly tuned, so everything is perfect. You're running 20 psi boost, the WOT BLM is locked at 128, and you've got the perfect a/f ratio. Life is good.
Then you go to the track, and up the boost to 25 psi for the big race. Now your tune is off. Still injecting the same amount of fuel as before, but you're moving more air, so you are lean.
You can raise the fuel pressure to get that fuel delivery back. You could also change the BLM lock value to do the same. Going from 20 psig to 25 psig (assuming the same intercooler outlet temperature) gives a 14.4% increase in charge density, the same increase in air flow, so it should require ~14% more fuel. If you change the BLM lock value from 128 to 146, that's a 14% increase, and your tune should be spot on again. Or at least closer.
Which brings up the real point of all this... couldn't the TurboLink boost harness be used to do this automatically? Call it a "floating BLM lock". ecm gets a MAP input via the boost harness, runs through a quick formula to get the ideal BLM lock value, and then uses that in the final inj pw calculation. Fueling is nearly perfect all the time, no matter what boost level you are running that day. If there was a way to get the IC outlet temperature as well as the manifold pressure then you could also compensate for summer/winter as well as changing boost levels, but since the MAT input is used for MAP with the boost sensing harness I don't think that's possible.
Anyway, just an idea I thought I'd throw out there. Don't know if it's possible, but maybe it'll stir someones brain cells.
John
. Steve Y. has been working on a mafless ME chip, using the tlink harness for map input - maybe this is a nice way to get the wot benefits of map while keeping all the part throttle and driveability of maf. Be an alternative to the extender, for sure.
