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My TBI computer chip programing thread/adventure.

y5mgisi

y5mgisi

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I have another thread going about the truck and have been cluttering the heck out of another one so i figured i should start a fresh clean one here specifically pertaining to the programing of my chip. The purpose is to cure a bad idle problem caused by a larger then stock after market cam that the computer does not work with. I just ordered my programing stuff today and have been reading like crazy on all things programing. BIN, ADX, XDF, VE, BPC, PE, etc have been pretty much all i have been thinking about for the past couple weeks or so. So, the purpose of this thread is to have one place to ask all my questions that i am surely about to have when i start programing chips. Or at least trying to.
 
Ok. I just did my first "tune" Pretty much just decreased fuel in the low RPM low MAP areas and eased them back up at higher RPM higher MAP areas. Also put the main spark advance from the performance tune bin in there. Wont get to test it until my stuff comes in the mail and i modify my ECM for the zif socket.
 
Couple screenshots of the changes. Amur bin,

fisrtattemptscreenshots-amur.jpg



and mine,

fisrtattemptscreenshots-mine.jpg




Specifcally, look in the 400-1200rpm range and the 40-60kpa range. Thats where i made the biggest changes for now. If you watch this video, (or look at my loggs) you will notice that my BLMs are all at 105 in this area. So i followed this formula for figuring out my new ve table, 105/128X(original table value). Turned out to be 82% of the original VE number for each given cell. So for example, the original value for 800rpm at 50kpa is 26.02. To figure out what i should edit my new table to in that location i would do the following, 105/128X26.02=21.34. I adjusted the whole table but at the higher rpms where it runs ok as it is, i only adjusted them 85-95% of original. The spark advance table is a direct copy from davew's 7747 performance tune bin. I know that this chip is going to be way way WAY off, but at least it will give me a feel for where i need to go.

The video showing my few blms,

 
Last edited by a moderator:
Here is a tuning tip I use. I ZERO a few tables to make tuning easier. The screen shot is for an International 304 V8, so don't use this information anything but an BONE STOCK International 304 V8!:eek1:

dave w

Ron's 304.jpg
 
I should have included this picture showing the front pins being cut down.

dave w

DSCN3377.JPG
 
Ok so you solder those 5 pins together then trim them down then solder it into place on the computer?
 
y5mgisi said:
Ok so you solder those 5 pins together then trim them down then solder it into place on the computer?
Click to expand...

Yes, solder the 5 pins pictured. Only trim down the front 2 pins on each side. Then solder the remaining 24 pins (rear 12 pins on each side) into the computer.

dave w
 
y5mgisi said:
I just got my socket in the mail! Going to attempt to solder it to my computer using this method,

EDIT: Dave and Mark, if its not ok for me to post these pics here let me know and i will remove them immediately.

http://www.eagle-mark.com/Forums/viewtopic.php?f=23&t=205

Probably be a couple days before i can get around to it.
Click to expand...

Pretty much anything we do there is for sharing/helping/learning. Adding the link helps because sometimes websites do not allow pictures from other websites...
 
Turns out, it seems my stock computer is a 8747 and my junk yard comp is the 7747. Can i just program the 7747 to fit my needs?
 
y5mgisi said:
Turns out, it seems my stock computer is a 8747 and my junk yard comp is the 7747. Can i just program the 7747 to fit my needs?
Click to expand...
I'm curious, did someone swap that ECM in there or was that a Big Block truck origanally? I just can't remeber an 8747 being on anything other than big block. This was all hands on, I have not looked any of this up...
 
No the truck is a "K" LO5 350 originally. Heres the thing, i put that computer in there about 5 years ago when i thought it was bad. I just went to the parts counter and told them what i had and the 8747 is what they gave me. I swaped my chip into that computer and ran it. What i couldnt tell you is what computer it had that i took out. Then, still thinking the computer was bad, i went to the junk yard and got a 7747 out of something. Both computers ran the truck the same in the driveway at least. I know that my 8747 reads the knock sensor casuse in my logs it will come up with knock counts sometimes.
 
Autozone lists both of them as for "For your 1990 Chevrolet Truck V2500 3/4ton Sub 4WD 5.7L TBI 8cyl"
 
I am by no means an 8747 expert. I think the 8747 is used for the TH400, and I think the 7747 is used with a TH700R4.

It would make sense that all sensors will work if a 8747 and 7747 were swapped, because the wiring harness is the same. I noticed the TCC and TH400 Kickdown are wired to the same ECM pin. It would make sense that when the TCC is supposed to unlock, the TH400 Kickdown would need to "kickdown". It would make sense that the .adx files would work with if a 8747 and 7747 were swapped because the ECM ALDL data stream pin is the same wiring and both computers are 160 baud rate.

dave w
 
Im thinking so far that im going to stick with the 7747. I believe that i can make it work out for me and it seems to have a bigger following. I think that would be the right thing to do? I remember reading somewhere that you could make the 7747 work to downshift the th400 but i dont remember where. Talked about inverting the signal and all kinds of other stuff. I think i will just downshift manually...
 
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