Anyone a Tuning Guru, couple of questions:

[Fastbird]

This concerns tuning a 93 Trans Am:

Now before anyone cries foul on me for playing with the VE tables, it's a speed density 93 car. I don't need no obstruction in my induction.

Also, this is just for my learning purposes, I have no intention of running a modded tune (from my actual tuners tune that is) until I have figured out a fix for my split BLM's.

Now, I've exported my Datamaster log to Excel with the following parameters:

RPM, MAP, Left LTerm, Right LTerm, Fuel Trim Cell

I sorted first by Fuel Trim Cell, then by RPM, then by MAP.

Here's the question: do to my stupid Split BLM issues (still gotta drill my TB, but I'm jsut playing right now, not running these tunes) I don't have an equal BLM on the left or right most of the time. Most of the time it's only a split of 2-4, but sometimes there's an anomale where it's a 30+ split.

I'm using the average formula in excel to compute the average for each RPM/MAP block, then using that average to compute a percent change necessary to bring my BLM average up to 128. IS THIS CORRECT???

Should I discount the anomalous VERY wide split BLM splits when they appear, or include them???

And, here's another question. I'm just computing averages, and I noticed that I have the same map/RPM values IN DIFFERENT BLM CELLS.

I thought the BLM Cell Boundary tables made out where the cells switch over. How can I have the same values in two different fuel trim cells show up in the same VE Table cell, and how do I make a correction based on such information if it's differing (one right on, one way too rich)??

[Fastbird]

Unless........

Should I even be concerned with what fuel trim cell it's operating in and worry more so about the overall MAP vs. RPM scope??? Arent' the fuel trim (BLM) cells just used for a "history" or learn of sorts???

[Fasterthanyou]

Originally Posted by Fastbird

Unless........

Should I even be concerned with what fuel trim cell it's operating in and worry more so about the overall MAP vs. RPM scope??? Arent' the fuel trim (BLM) cells just used for a "history" or learn of sorts???

Dont' concern yourself with the BLM cell, that'll just give you a good overall idea of where the tune needs work. Example, in cell 1 you might be idle for 90% of the dataloging. So look at where the car idles (which rpm and map) and adjust the cells accordingly.
As for split BLMs, you need to ignore the huge splits although it would be interesting if you noticed the splits in only one condition like deceleration or high load acceleration. In general though just use the datalog, run it through excel and get an average. How many miles are on your engine? You could have deposits on the injector pintels that are causing the split BLMs, this isn't uncommon for older port injection. The newer delphi injectors are a lot better at resisting deposits! A pressure leak down test will tell you know about the injectors and everything about the fuel pump, so don't even bother with that kind of a test. Just grab the LS1 injectors for $100 brand new take-offs, it's cheaper than cleaning your used injectors .
If you need any help tuning let me know. I've been known to dable with these kinds of things from time to time .

[Fastbird]

Jon, check out my web page for info on the car. Almost 100% of the motor is less than 1K miles old now. It's the black car btw.

Injectors are less than 1K mile SVO 30#. I'm 90% sure that my crazy BLM split is because of the BBK TB, which I'm going to be drilling the bleed hole within the next couple of days.

My biggest problem is going to be getting a PE/Open Loop idle without having to do a full open loop tune.

[kamikaz]

You got a DFI for that thing?if not i got one for sale

Later,

Santos

[Fasterthanyou]

Why not do a full open loop tune? Does the car still have cats?
I'm a little confused on the slip BLM being related to the TB. Do you have a link?

[Fasterthanyou]

Originally Posted by kamikaz

You got a DFI for that thing?if not i got one for sale

Later,

Santos

He's already got DFI, came from the factory . Really though, DFI is over-rated and overpriced when you can work the same magic out of a GM PCM. The only difference is the easier interface which I think diminishs a persons ability to fully understand how things interact. I could go on and on but the only time DFI is worthwhile is if you've got an all out race only car or a really funky engine swap that has nothing similar. Think about it, what does the DFI really offer of a stock computer? I can't control the emissions equipment, it has not good base starting point, it's an expensive part incase you fry it. For a GM car with a GM motor, stick with GM electronics, they'll give you the least headaches and best drivability.

[Fastbird]

Originally Posted by kamikaz

You got a DFI for that thing?if not i got one for sale

Later,

Santos

No thanks, especially after seeing how much trouble a buddy from the Speed Density board went through with his Accel Gen VI DFI.

Originally Posted by Fasterthanyou

Why not do a full open loop tune? Does the car still have cats?
I'm a little confused on the slip BLM being related to the TB. Do you have a link?

Sure thing:
http://para.noid.org/~lj/PCM%20Tutor...litBLMinfo.htm -- PROBLEM EXPLANATION
Fixes:
http://www.chipsbyal.com/idle/index.html
http://www.hashmarks.com/techtips/throttle_body_mod.htm

I don't want to do a full open loop tune mainly for the fact that I can't monitor the system as well as I could in closed loop. I'm getting contradicting feedback on whether or not adjusting the TPS Threshold for PE Mode tables down at 400, 800, and 1200 RPM will actually work since the computer still uses the last known Block Learn when it goes into PE mods. Sadly, I can't get BLM Locker to work on a 32K .bin file to lock the WOT (PE MODE) BLM's at 128 like it would be in closed loop.

Fasterthanyou, I REALLY REALLY appreciate the feedback on this. I've only just jumped into the actual tuning parameters in the past couple of days but fell I'm catching on VERY quickly. I just need refinement and a little guidance, and I appreciate that.

[Fasterthanyou]

I've been lurking over at the speed density forum and am saddened by the quality of replies. I'm not trying to tell you to ignore everything they say, just don't listen to the guys that tell you out right what to do. Nobody can tell you what's the best option unless they spend a lot of time with your car hands on. I can't tell you how screwed up those guys are with thinking they can "tune" a car through the mail and datalogs. They know diddly if they think that's good enough, I've NEVER been impressed with any mail order "help" me tunes and they think they're doing people a favor .
SO, if you've got cats (you haven't told me yet) then open loop tuning is out of the question. The cats need rich/lean to work, anything slightly rich all the time will overheat the cat and you'll end up spitting molten balls of cat out your tail-pipe.
If you do the mods that are suggest please keep in mind that you should mechanically lock the pipes into the TB. You do NOT want one coming loose and going into your engine!
I'm assuming you have your own burning equipment, could you tell me exactly what you have as far as hardware and software? This way I can help with more detail.
If you want to learn how to TRUELY tune a vehicle visit thirdgen.org DIY-EPROM board. Questions there will usually yeild much better answers than else where on the web.
Do you still need a tuner for the dyno day next weekend?
edit- "I think it works like this" from the link you gave me above about PE mode. This is annoying, in the 93 ecm all the code is on the chip so why hasn't anybody hacked the ecm like the thirdgen community? Somebody in the 4th gen world that's an EE should do it for the rest of you guys. This would give you answers, not "I thinks".

Hey Jon, you ever do any 350 TPI tuning? i gotta find out the specs on my cam then id like to do a little tuning but have no idea what so ever as to what to do and was hopin you could help.