and even though it didn't relate to my MAF car directly I learned a bit...correct me if I'm wrong...

1) That I need to get an average of the blm values for my airflow in my MAF tables...I can only capture 81 frames in my MPSI scanner...but with that I should be able to do a number of runs and record the data...thus getting an average of the values

2) That if I use Traxxion's method( I think) directly, I need to let the BLM flatline before I write down a Airflow/BLM number...which is what I haven't been doing and I think that explains my changing BLM values...

3) That I have alot to learn...but that I think the VE tables in the SD files function basically the same as my MAF tables do...so by thinking about that...I think I can use some 730 info on my MAF promburning adventures.

OK, now using that info and the graphing function of Tunercat(thanks for reminding me it's there...I had forgotten...I bet if I look at my fueling curves they are NASTY!)...I should be able to maybe model a best fit curve in Excel or something similar and be able to pinpoint my values...right? Will the fuel needed for the car to run properly increase proportionately to the RPM and Load...or is it more of a bell curve?

Thanks,


------------------
GregF
87 IROC

 

Greg, set your data capture rate to 5 (I think it defaults there) so that you capture a longer time of data, which should give you approx. 35-40 seconds to vary your RPM and load to cover most of the BLM cells. Yes, averaging the values over a few runs or so would help. But with the corrections the computer makes, just letting the BLM stabilize in each BLM cell before writing down airflow and block learn numbers would help tremendously instead of chasing the BLM while it's still moving around.

I don't think the VE tables compare very well with the MAF tables, or even the base pulse width tables. The MAF tables basically calibrate the MAF voltage to the grams/second of airflow to allow the computer to accurately compute how much fuel is needed for a specific amount of airflow. Since that's not a perfectly linear relationship and changes to the MAF sensor (like taking out the fins and screens) or even the intake tract before the sensor throws off that calibration, the MAF tables allow GM (or us) to correct it so that the voltage reading more-correctly corresponds to the actual airflow rate. Of course, this is seen through the BLM values at various airflow readings, through feedback from the O2 sensor.

AFA the fuel curves, I'm guessing you're talking about the Power Enrichment (or WOT as TunerCat calls it) tables. The PE vs. RPM table is probably the first one you'll want to work on, then move to the PE vs. coolant temp once you have your O2 numbers fairly level while making a run up the rev-band. My curve is like a bell-curve, but of course the shape and size will vary for each different engine. Just watch your O2 sensor and adjust the amount of fuel added at whatever RPM you need to adjust that table.

If you're talking about the base pulse width tables, I don't think they're in the '89 code. Plus, they're just straight linear tables (as seen in the BUA hack) and shouldn't need to be messed with since all they're doing is giving the computer a baseline to work with. I'm not even sure if they're used in the pre-'89 codes either since the computer is constantly calculating the correct injector pulse-width, except in open loop I guess... Oh, those tables are linear going up in RPM and in load...

------------------
Greg Westphal
'87 IROC 305TPI/A4

 

I thought so...



Yah, but the VE tables are what tells the SD computer how much fuel to dump into the engine and the MAF tables indirectly tell our computers what to dump into the engine...right? Thus they serve the same function...



I was talking about the fueling curve indirectly as the MAF tables curves...I am thinking of the MAF tables as the fueling tables...which is what I see them as since if you tweak the numbers down it takes away fuel and if you add it adds fuel..thus it controls the fuel. Right?

Nope...I recall the BPW tables in the 87 code and that's why I was so lost when I started on the prom tunin' for the 89...I thought those BPW tables are what we modified...I have since been edukated...some.

Thanks


------------------
GregF
87 IROC

[This message has been edited by gsf-87IROC (edited March 26, 2001).]

 

WOW...looked at my curves and they were suprisingly smooth...but the ones that weren't were the low down ones...right where my car breathes on the interstate and around town...smoothed those out and once the sub-arctic air leaves southern Indiana...I'll test it out.

GregW-you had mentioned a few days ago about the MAF tables and making sure the first/last values gived on all the tables...that was one of the first things I did...DaveT mentioned that to me...since he had gotten caught by it...interesting...




------------------
GregF
87 IROC

 

Yeah, although I think you have it backwards. The MAF is (indirectly) measuring the airflow, so then it knows how much fuel to add based on that quantity. The VE table is a guess at the engine's effiency at particular RPM and MAP values, and then calculates the amount of fuel needed. So, yes, they do serve the same function in that sense.

Yes, it's just that I thought of them as being different than the base pulse width and VE tables since those are 3D tables and the MAF tables are 2D. But you have the right idea. Hope I didn't confuse you any more.

------------------
Greg Westphal
'87 IROC 305TPI/A4

 

It is an impossibility to confuse me any more than I already am...so don't worry about it. OK, maybe I'm not that bad...but sometimes it feels like it.

It is truly amazing how some offhand comments by people can make the light bulb come on for clueless others(aka me)...


------------------
GregF
87 IROC