Dave D

hi and thanks for reading this. I have a 1998 formula that Leading Edge performance built a 408 ci for it, and ran a speed density tune. Cam is 242 duration. Anyway, we have been experiencing surging and dying out at idle. idle is set at 1200 rpms in drive, and about 12-1400 in park. The tuner thought the 98 ecm is too primitive, so we ordered an ECM off ebay. The shop programmed it for a 2002 trans am with 4l60 trans as that is what I have (stage 2 setup). it surges at a stop light and I have to keep the foot on the brake and gas pedal. I am also running a Yank 3600 stall and 3.23 gears which will be upgraded to 3.73s with the Moser 9 later on. Well we got the ecm, and it said it has been tuned for a 2002 and my vin number has been inputted. The shop that sold me the computer said it must be re-pinned to work in the 98, and he said it should have 98 software to run the application, then put the speed density tune on it. Does this sound right?? Has anyone put the 2002 ECM in a 98? wouldnt loading the 98 OS cause the same problem?? what is meant by re-pin the wiring harness?? Thanks for the help!!

techrunner

iTrader: (4)

repin is just that the pins in the 98 harness are not the same for each signal as they are in 99-02. the pins on your 98 need to be carefully labeled and removed from the ecm connector, and then reinserted into the correct locations that the 02 ecm will look at. you basically need ot get the pinouts for both te 98 and the 02, and rearrange the pins in the connectors.

not sure what you would want the 98 software loaded on there for, the whole point is to get the 02 ecm to control your engine, but i'm not too far into the programming end. i'd ask them what they mean by that directly.

RUTAN TA

I would use a different OS like a 12212156 over a 98 OS anyday! I had a 98 TA with a 24x/25x cam with a 98pcm that was tuned in SD that i repined it to a newer pcm using a 12212156 OS and had alot better drive ability

Dave D

Thank you all for the info you provided! It is really been a big help. My engine builder wants to use the 02 OS and then put the Speed density tune on it, but the ECM store that I bought the ECM from was afraid the 02 OS wouldnt work with the 98 setup. I am really glad to find that someone here was able to use the 02 in a 98 setup! My cam is a 242 duration, and dies out at idle or coming to a stop. The engine builder said its due to the 98 software.
My next question is how do I repin it, I see what you are saying about labeling the wires, but is there a way to find which one goes where? Or do I need to get both wiring diagrams for both models?? Thanks for the help!!!!

flame

iTrader: (13)

Here is a link that has info on repining http://www.chipsbyal.com/convert98/

RUTAN TA

It is not the 98 software causing it to die out and you cant load a 98 file into a 99-02 pcm. I would think its time to talk to your tuner and have him fix the stalling issue if its tune related.

kamikazematt

have him look into the throttle cracker tables and to also redo the base running airflow.

edit-look into the bottom end of the ve table, not to mention making sure that the primary and secondary tables match.