thunderhorse

I recently put in BBK LTs along with a catted h pipe and catback exhaust on my 2002 GT. Understandably, my stock computer did not like the new location of the O2 sensors and my engine light would be on along with an occasional weird idle session fluctuating between 500 and 1000 rpms. To fix this, I bought a SCT SF3 tuner from AM. I got the custom tune and everything.. uploaded it to my car, works great the night I tested it out.. no engine light, regular idle. The next day my engine light comes back on and the weird idle returns. Did my car not remember my tune? I looked up the trouble codes on the tuner, and they are for the O2 sensors.. I cleared them twice and both times the engine light and identical trouble codes had come back. What's going on with my car?? Thanks for the help in advance.

ct_white_stang

This problem sounds o so familar seeing that I just went through this. What are the exact codes you are getting? I tried to go with a custom tune from Bamachips and I keep getting the check engine light. I just brought it back to where I got the LT's installed and had them tune it with Sniper Delta Forces. Problem solved.

cliffyk

When LTs are installed the O2 Transport Delay table has to be modified to allow for the extended delay between the PCM commanding a specific AFR and the O2 sensors detecting the change. This is common knowledge among competent tuners...

thunderhorse

I just had one of those free custom tunes from Americanmuscle.com.. I did inform them that I had LTs on... hmm.. maybe I'll just ride it out for now until I eventually get it dynoed? It's just frustrating because I paid a lot of money for that tuner.. and for it not to work properly is quite annoying.

thunderhorse

After retrying it today.. the car will remember the tune once I start it up for the first time after uploading. As soon as I turn it off and start it again, it forgets it. Any suggestions?

ct_white_stang

It's not forgetting the tune. Is it because the check engine light comes back on after you start the car up for the second time that your thinking it lost the tune?

cliffyk

+1, it cannot "forget" the tune--re-flashing the tune requires that specific signals be applied to the OBD2 port, it's not something the PCM can do by itself...

thunderhorse

yes.. the check engine light has been the problem. After retrying for a 3rd time, it looks like I might have stumbled upon some luck. After using it twice (on and off) the light has been nonexistent and I believe everything is ship-shape. Thanks for the help guys!