I have just gotten used to burning proms (with factory data) and am now ready to modify some tables, Main Fuel Table vs. Near Idle vs. %Vol. Eff. table. I read Traxions excellent article on "Part Throttle Fuel Tuning (NO PE)". I used Datamaster to record data at 200 RPM increments from 600 to 1800 RPM's. The data aquired during this test run seems odd.


RPM Kpa BLM
600 38 135
800 34.3 136
1000 32 138
1200 28.4 144
1400 27 150
1600 26.2 158
1800 25.9 151


As you can see the 1600 RPM data row has a BLM magnitude of 158. Thus 158/128=1.23 and 1.23x75(factory data point)=92.5. 92.5 is the highest reading on the scale and it gives the graph noplace to go at higher engine loads! This doesn't seem right, unless the graphs data is arbitrary and can be any value above or below the scales limits, it may be self scaling or adjusting also. I already upped the fuel pressure regulator on the TBI to see if that would help, all it did was move the data around a bit. It still has the highest graph data at the point with very little engine load (Kpa=26.2). Should I continue to take data at higher engine loads and calculate data regardless of the final number (I.E. off the scale?).

Just tryin to mod my first chip


1995 4wd auto E/OD GT4 Suburban:
I have replaced the original 5.7 motor with a 355 c.i. split rear oil seal short block, a Crane cam [part # 113931] with intake lift at valve .440" and advertised duration of 266° and exhaust lift at valve .454" and advertised duration of 272°, a pair of 23° twisted wedge Trick Flow heads, K&N air filter. 1 5/8" Flow Tech shorty headers with O2 sensor coupled to 2 1/2" dual exhaust with dual cats, mufflers and no crossover tube. The motor is topped off with some 8mm ignition wires. The rest of the motor and car is bone stock.


Still climbing that learning curve!

Thanks,
Tedd Edmondson

 

I'm not familiar with your set up but the earlier TBI masks had two VE tables and they were added to each other. So you could go higher in VE by just touching one table. Do you have something like that?

 

Yes there are two VE tables, one for idle through 1800 RPM and the next table represents from 1800 on up past 6000 RPM(my truck shifts at 4200 so i'll just program to 4500).

After I entered all the data I had aquired, I noticed that the table was self scaling and would change its limits according to min. and max. values in the table(As long as it's value is between 0 and 100).

I've just got back from my first drive with a modifyed bin:lala:
And I did notice that the BLM's from idle through 1800 RPM were alot more inline, and in a few instances were right on "128". That was not the case before, BLM's from mid 130' through 163!! After seeing the improvement I continued the second "Data Drive" and tried to get more readings at differing loads to try and get a wider path of data. I assuming that there will parts of the graph that will never be reached under normal driving conditions, much less extreme driving conditions! And these area will be "smoothed out" on the table graphs visually.

I feel I'm beginning to get a handle the process and it's addicting

I've got my second batch of data staring at me so off I go!!

Tedd