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My TBI computer chip programing thread/adventure.

Good work! It's not easy to do something automotive that's not covered in a service manual!:waytogo:

Sure enough, the Automotive Service Manuals have procedures how to re-flash the newer OBDII PCM's, but not one mention of how to modify the what's being re-flashed.:doah:

Want to impress a Master ASE certified Automotive Service technician, show and tell how you flash your own chips!

dave w
 
That's your first soldering job on a board? :waytogo:

The 2 that are a problem sometimes are in your picture top right and bottom left. You can see they are a little differant.
 
Your nose is no where good as data! Especially if you have removed your cat!

Have your tuned for the cam yet? If not then yes it will be rich. Start by turning down about 6-8 cells around idle rpm and low MAP kpa. What did that do for BLMs? Have you added any timing at idle yet? Same cells differant table and increase by 2 degrees, watch map reading. Did it go up? If so add 2 more, did it go up? If neither than go back to stock and remove 2 degrees. Did the MAP go up? See where this is going? Then go back and look at BLM for idle. Adjust those cells again.

This may sound easy because I have an Emulater and do it real time, no chip burn each time. Now you will understand why a Zif socket is so helpful.
 
I hear ya on the nose not being as good as data! Just when I first had it running I didn't have laptop hooked up yet. So, what I did was took out about 25% of the fuel at the idle rpm and map and eased it out from there to 20%, 15% and so on the further away from those trouble areas that i got. As far as timing, I added Dave's 7747 performance tune which seemed to mostly be a few degrees above stock everywhere and smoothed out some. Right now, that's about all I'm tuning for is idle. I will post up the couple logs that i got today. The map is very much improved so far. Now, my blms are still mostly in the 108-112 range which is way better then the solid 105 it had before! I'm thinkin over the long weekend I should have it pretty well whooped.
 
Geesh, just went back and looked at the solder pics, they sure do look bad! But believe me, in person, they just look less then professional but certainly not too bad.
 
Here is the crappy little video i took. Its right after i started it so it was still cold.

 
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Don't worry about cold start! All cold settings are based off accurate fuel tables!

Get your idle right, then mid range, then 3/4 throttle, then WOT, then smooth the tables.

If you have cold start issues work on them after fuel is close. Fuel needs to be close before you can work on spark but since dave gave you a spark table I think thats done. when BLMs are good all around then look for areas of knock. Since Dave did the spark you probably won't find any...
 
Oh yea im not worried about the cold start. Just giving a little background on the video. All im really concerned about is the hot idle. Thats the only area where it ran bad. The rest of the time, it ran fine but im sure it wasnt quite right. So im trying not to mess with the part/full throttle stuff right now casue im just not all that concerned about that until i get it to idle mo betta!
 
One tuning method that might help, is to lower the miminum BLM number to 92, and increase the maximum BLM number to 168. I personally don't like changing the BLM min / max numbers, but there is nothing wrong about changing the BLM min / max numbers. Changing the BLM min / max will allow more room for the Int to work it's magic. Having wide swings in the Int is not good. Usually the Int will compensate OK if all the VE table is to rich or to lean. Sometimes the VE is so far out to lunch, there is no other option than to adjust BLM min / max.

dave w
 
dave w said:
One tuning method that might help, is to lower the miminum BLM number to 92, and increase the maximum BLM number to 168. I personally don't like changing the BLM min / max numbers, but there is nothing wrong about changing the BLM min / max numbers. Changing the BLM min / max will allow more room for the Int to work it's magic. Having wide swings in the Int is not good. Usually the Int will compensate OK if all the VE table is to rich or to lean. Sometimes the VE is so far out to lunch, there is no other option than to adjust BLM min / max.

dave w
Click to expand...
You sure about that? on 1227747... I was always told not to touch them and I never have...
 
That is a good thought, but im pretty sure that i will be able to get mine under control with just the BPC and VE table.
 
eagle mark said:
You sure about that? on 1227747... I was always told not to touch them and I never have...
Click to expand...

It's OK to adjust the BLM min / max. Sometimes when I start tuning a '7747, resetting the BLM's is the only way to get the engine to run and data log.

dave w
 
The loggs from today.
 

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  • 20110901_115918_LOG.zip
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  • 20110901_114801_LOG.zip
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Ok so i just made some adjustments. Added a couple degrees of timing at "those"rpms, took away 10% fuel in those rpms, adjusted the minimum BLM to 100 from 108 and adjusted the BPW from 135 to 130. We'll just see what that does. Worst case, i load up amur bin and start all over!
 
y5mgisi said:
Ok so i just made some adjustments. Added a couple degrees of timing at "those"rpms, took away 10% fuel in those rpms, adjusted the minimum BLM to 100 from 108 and adjusted the BPW from 135 to 130. We'll just see what that does. Worst case, i load up amur bin and start all over!
Click to expand...

After looking through the logs posted, I agree with the BPW change from 135 to 130.:waytogo:

I would recommend not changing individual VE cells until logs show that most of the BLM's are getting near 128.

BPW is a Course adjustment.

VE Table Cells are fine adjustments.

Not everyone tunes the same. I imported and then combined both the .txt logs into Microsoft Excel. The overall average BLM was about 112 (111.83). The average was for all RPM's and all Maps. Changing the BPW to 130 should move the overall average BLM's closer to 128.

dave w
 
dave w said:
It's OK to adjust the BLM min / max. Sometimes when I start tuning a '7747, resetting the BLM's is the only way to get the engine to run and data log.

dave w
Click to expand...
Well dam... I'll have to try that. Whenever I have a problem child I usually read codes first, then disconnect batt which clears codes and stored learning, but never increased BLMs

y5mgisi said:
Read!

http://www.docstoc.com/docs/58166745/How-GM-Electronic-Fuel-Injection-Works
Click to expand...
That document looks like the Custom EFIS handbook. His website is gone so I guess he stopped doing systems. I got one of his handbooks from a guy who wanted me to install his system about 5 years ago. Really good information!
 
Got the chip re programmed. Gotta go into work early today so I can't run it until tomorrow. Curious to see what that round of tweaking did for me.
 
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