Suem

Hi all. New to the forum. Been having issues with my 1998 LS1 trans am. Initial problem was rough idling and car shutting down when putting in reverse.

Shop replaced air injection pump, fuel pump and O2 sensor. Determined needed ECM fixed.

Sent ECM off to be fixed, installed and tuned repaired ECM. Car ran great until WOT - upon WOT car backfires and shuts down but able to start it right up.

Shop decided the ECM was not fixed correctly and Installed a second fixed ECM. Exact same symptoms upon WOT. Shop has washed their hands of it. Considering going to a local high performance shop but wanted to run by the experts on here first. Does this sound like a bad computer? Bad tuning? Electrical? Is this fixable? Any suggestions would be a huge help.

I don't know all of the mods that have been done to the car since I am not the original owner. I realize knowing the mods would help but I can't change that.

G Atsma

I wonder if the TPS is shorting out at WOT, causing ???? electrical problems?

Suem

Thanks for responding G Atsma. Something to check out ��

statesman

Do you have a diagnostic trouble code reader?

If you don't have one, you should get one... they're fairly cheap and you'll be able to see quickly and easily if the ECM has detected any faults.

fst100

iTrader: (5)

I'd check if the cps is bad

edit- cps is crank position sensor

Suem

Thanks all. No codes are being thrown and the shop said they changed the cps. Appreciate all the ideas!

fst100

iTrader: (5)

I'd make sure it was plugged in securely.

Suem

Thanks fst100. Just to clarify, make sure what was plugged in correctly?

fst100

iTrader: (5)

the CPS sensor.
found this via google a bit ago
https://ls1tech.com/forums/pcm-diagn...backfires.html

Suem

Got it fst100. And thx for the link!��