mod with high stall convertor

[NC87GN]

Can someone share with me the chip mod to prevent a GN from stalling with a high stall convertor. I have already implemented the same mod as Lubrant does by increasing IAC at 32*C by 20 and 56*C by 40. In this case it did not work out to well. This car has a very loose convertor and goes down to 400-500 rpm at a stoplight before it completely stalls. It is a 9X11 from Bruce T and stalls to 4000 on the brake. I have direct scan file where you can visually see the rpm hit 500 rpm letting off the gas after an 1/8 mile run. Any help is appreciated..

M. Banas
87GN

 

[TurboJim]

The mod has nothing to do witrh stall, it has to do with inertia and the weight of the converter. Personally I think with the 9x11 you have another problem as its almost the size of the stocker. Maybe what, 5-10;bs lighter? Anyway, make sure you have minimum air set right. If you did your own cxhip, if you set the idle say 100rpm higher than stock (say 775 vs 675) you need to raise the min air by the same amount. If stock min air is 550, set it to 650 now.

Anyway,

One solution to the "let off the gas stall" if you're POSITIVE its a calibration issue, is to set DFCO enable temp at $3445 to FF. The other is, let me think, nah, I haveta look at home. The jist is increase the IAC cycle loops, change how fast it reacts, and one other thing, think limit how fast it can move in the closing direction. I wanna say $368E and $368F to 0F and $3690 to 0F...but if you can wait, I'll check my notes at home.

 

[NC87GN]

Thanks Jim... I'm gonna go and do some things you recommended such as raising the min air proportionally to idle rpm's. Also going to try 68E, 68F, 690 to 0F also. Please give me a shout if you find your notes and drop me an email. I'll drop you an email from my home addy as that is where all my software is.. Thanks again Jim..

M. Banas
87GN

 

[BM Computer Src]

Mike,
I apologize for not having more detailed information for you. Most of what I have learned about this problem and fixing it in the chip came from Jim. Looks like he already gave you the details anyway.

Thanks Jim!

Bob

 

[NC87GN]

OK, a little update. First I modded a known good chip for kicks (lubrant 93) chip by changing 68E, 68F, 69E to 0F. Calculated checksum by highlighting 02-FFF. Put 1E, which is the checksum value from Hex Editor, in 00 block. Car idled great and did not stall! Cool! However the car missed and backfired (check engine light flashing occasionally) when I was under boost... Hmmmm? Thought it may be bad chip so tried another. Same thing. Is it the way I am modifying the checksum and saving? I'm am verifying through TunerCAT checksum and states that everything is AOK. Thanks in Advance for all the help!!

M. Banas
87GN

 

[ijames]

You need to calculate a 16 bit checksum and put the high byte in $00 and the low byte in $01.

 

[TurboDave]

Carl beat me to it

Basically the checksum, as he said is a 16 bit word. What you will see is two 8 bit words. these are then placed in locations 00 and 01

You read it the right range, just not a 16 bit value

 

[TurboJim]

Or, and I've never tried it, but you could mark the chip experimental and set $37A2 to AA

That is supposed to bypass the checksum check

 

[NC87GN]

Thanks all!! Will try out tonight and let ya know how everything went...

M. Banas
87GN