Hey everyone,
I just made my first datalog. I did a 4th gear full throttle pull from 1900 to 4600rpm. This is what it spit out. Please help me understand what this is telling me. I am getting most of my knock during my shifts. I see that my TPS never hit 100% I guess I need to adjust it. When my foot is off the gas, it registers at -1.8%. Let me know what you see & how you saw it.

Thanks in Advance,
Mark B




One more thing. I know what MAP is, but why is it a value in just about every chart? I dont understand how it relates to other values in the ecm & how I can use it to enhance performance.

 

Without having a Wide Band O2 sensor, doing WOT stuff is not really useful to determine tuning parameters.
When you go to WOT the corrections get "locked" at 128 (see your log) and no corrections to fueling are made. (For the sake of this post I'll state it that way to not confuse the issue)
The stock "narrow band" sensor will report back and cause the BLM and INT to correct for fueling that is not at the "perfect" ratio.
The optimum is 14.7:1 and when doing "light" cruising (not getting on the throttle) The difference between 128 and the BLM value for that particular RPM and MAP load, will indicate if you are rich or lean.
Values above 128 mean fuel is being added, values lower than 128 means it is being subtracted to achieve the proper burn mixture.
Do some more driving (I know, that will take some convincing) and try not to accellerate too quickly and see where your fueling needs to be changed. Make the changes to your table in the bin and do it again until they are pretty good.
Keep in mind that if you put too much throttle you will get into AE and PE which makes the BLM number false because of the additional fuel calculations.
Have fun

 

I have lots of data logs from just crusing around... But there doesnt seem to be any pattern to the blm's. They are always jumping around.

 

Plot the BLM's out vs MAP vs RPM and that's how you tune the VE tables. If you use excel, try and ignore data that isn't "good" like PE mode or open loop where the BLM's aren't doing any learning. Some newbies look at the high RPM high load BLM's and see 128 in their datalogs and think that they're OK when they could be far from. A lot of mask's lock the BLM's when in open loop and WOT, at least for 91 TBI camaro's they do.

 

Why do mine stick wherever they are?

SPEED---TPS-------RPM--------MAP-------BLM
37------(-1.2)------1050--------31.8------118
35------(-1.2)------1000--------32.5------117
34--------2.1-------1025--------38.8------116
34--------7.9-------1550--------50.2------128
35--------8.4-------1575--------49.1------127
35--------8.4-------1600--------48.4------126
36--------8.4-------1550--------48.4------126
37--------8.4-------1675--------46.5------126
38--------8.4-------1600--------46.1------126
39-------12.3------1800--------53.2------125
41-------18.1------1175--------80.8------108
42-------30.4------1275--------90.4------112
43-------47.5------1325--------96.7------115
45-------71.2------2175--------71.2------119
46-------99.6------2575--------97.4------119
49-------99.6------3550--------95.2------119
53-------99.7------3775--------94.9------119
56-------88.1------4100--------94.9------119
58-------58.6------2700--------93.1------119
59-------44.1------2175--------90.8------121
60-------40.3------1650--------91.5------125
60-------37.9------1675--------90.4------124
61-------21.9------1650--------74.2------125
60-------20.5------1675--------62.3------127
60-------15.7------1675--------63.1------128
60-------15.7------1675--------62.3------128
60-------15.7------1650--------62.8------127
60-------15.7------1675--------63.5------128

The tune is a little off, but that is the VAFPRs transition from vacuum to no vacuum and back.

 

your knocks could be mechanical noise. your MAP of 100 is WOT and at atmosphereic pressure(no vacuum). idle is about 30 map. deacceleration at higher speed with foot off gas would be like 10-20 MAP (mucho vac).

why 23 sec to go from 40 mph to 100? cant read vehicle description. maybe a truck?

 

I'm not real familiar with the TBI code but to me it looks like "learning" was disabled (as you went a little rich from accel) just as your TPS level was raised you can see it stop changing.
Looks like it stopped changing BLMs at about 50% rising and restarted at 45% falling.

 

He said it was a 4th gear pull from 1,900-4,600 rpm at the beginning. Its a car because it has an IAT.

Edit-scratch what I said, got to looking and it is actually in seconds. Sorry for any confusion it might have given.

 

Certain TBI code has the BLM locked to 128 when your in PE mode, not all. There is also the PE mode delay in tye 7747. With stock calibrations the delay is rather large, I think it's like 5 seconds. So during this time you could very well be triggering PE mode with the TPS but be in that delay period where it's still learning. I don't know for sure but it would be an explination for the BLM's below 128.