From the top; here's what happened. I have an 02 T/A with a stroked LS2, heads, cam, the works. In the beginning, I had it on a dyno and tuned. Later on this guy out in Arizona tuned it for taller tires. At the time the IAC was shot and he tuned the car to basically not stall. I think he adjusted the idle and cracker. Then I replaced the IAC a few months later. Ran it during the winter without a thermostat and notices a lot of oil consumption and performance loss. I installed a thermostat and it still burned a lot of oil and hesitated a lot at WOT, then one day it started having problems starting, like it was missing for a few seconds then would fire up. It got progressively worse and eventually started backfiring and wanting to stall and the idle would climb to 2K then drop to 500 with backfiring every few seconds. It was also throwing the insufficient switching code. I parked it for a while until a guy I met hooked his laptop to it and noticed the right bank was running way rich but the left was fine. Then we checked the plugs, they were all blackened. I did swap the plugs with NGK 4177, fluids have been replaced and have MSD wires. I drove it to work this morning and at first the clutch was making so much noise, I couldn't tell anything else. The clutch calmed down and the car drove and ran smoother the longer I drove it. While in neutral it would rev up to around 2K then slowly fall back down to around 900 rpm; then a few backfires. Just a few minutes ago I fired it up and it never idled above 1K and ran very rough; like it's missing but I changed the plugs yesterday. It really sounds like half the engine is working. As it warmed up the idle started to slowly get steady, then backfire and the idle drops and stumbles for about 10-15 sec, then the cycle starts over again.
It was recommended to do a compression check and also get the PCM tuned again. I plan on doing both as soon as I can find a tuner close to Abilene. Mission impossible…
Looking for as many ideas and opinions as I can.

 

It kinda sounds like the right bank isn't getting spark. Have you checked the coils, harness, etc?

 

No. Didn't think of that. Any special way to check coil packs without the old arc a screwdriver off your knuckles technique?

 

If the IAC was bad and he did something to make it not stall... and then you put a new IAC in it and it uses oil and misfires bad? It probably ran pig rich and fouled the plugs out. I'd find out what he changed when the IAC was bad and change it back.
Sounds rich as hell... mine was doing that.

 

I contated the guy but I tuned it with him over a year ago and he didn't remember all of the details. Do you know what are the stock settings are supposed to be for RPM table, RPM with A/C table and IAC table?

 

Okay the car ran at least 40% better just now than this morning. I'll do my third run tomorrow to get a compression tester and will check for spark while I'm messing around with the plugs. If it keeps improving and the compression is good, off to Lubbock for a good tune. 2.5 hr drive though; a little nervous. Wish me luck or buy me tequila!

 

A data log comes to mind...

 

Well now I got a P0507 code. Back to the IAC issue and the tuning adjustments made to compensate for the previous bad IAC. I'm gonna buy the hp tuner software, cable and the how to tune software so at least I can say it was my fault if the car gets jacked up in the future.

 

Well I found out what was wrong with my car. Apparently the person who previously tuned the car disabled the car's ability to detect misfire, then advanced the timing way out of tolerences for a car with 11:1 compression. Can you guess what happened next? My engine had a stroke!!! Needless to say I took it to a speed shop in Lubbock, Tx and they're doing a complete teardown, cleanup and replacement of destroyed parts. $6,500.00 later, my car will be finished. Anyone out there in say.... Phoenix want to cover the bill for me? Didn't think so...