Have you tried running the Torque app to make sure the fuel out map isn't running too lean? Do you remember the CEL(s) you got while driving?

I don't have the app or the OBDII bluetooth connector so no. It showed the traction control symbol + CEL.

I have Torque, the OBDII, and Unichip. Everything looked great on the standard maps for me (TRD Intake 93 and 89). Perhaps I'm too cautious but the fuel out maps are something I wouldn't want to venture into without monitoring the AFR closely. The AFRs are reliable with Unichip because it's read from exhaust not the MAF.

nope never had a CEL. it generally holds just find around 650 or so. only dips close to 500 when the ac is on but never stalled. yet.

I'm getting the CEL with the same story. No unichip, just a blitz cat-back. Anytime I rev to 6000 RPM on any gear, traction light lights up and then a check engine light comes on and the only way it goes away is if I ignore it for 2-3 days or disconnect/reconnect the battery. Never mapped my car's ECU, any idea?

I just bought the most reviewed CEL scanner on Amazon and cleared it. It's been fine since and haven't had another CEL since. Before I'll go to the dealer I'll dis/reconnect my battery though. I had some weird loss of pull and could only get to 45mph redlining 1st-3rd after clearing the CEL. I'm not sure how it'll work for you though since you don't have a Unichip to switch maps to fix that issue.

Will Techstream do it? because I've ordered one for the annoying seatbelt chime and waiting for it to arrive if not please send me a link to the scanner that you got and I'll order it I guess.

Not really sure what TechStream is, sorry :(
Here's what I ordered: [ame="http://www.amazon.com/gp/product/B001LHVOVK/"]Autel MaxiScan MS300[/ame]

I would take it to the dealer for a diagnostic. I think the trac warning and CELs are linked as a safety precaution, it could be anything. I doubt it's related to the cat-back, but I guess anything is possible.

This post isn't addressed at us, but I hope nobody minds a quick thought.

The P0172 normally results from a small vacuum leak between the throttle body and the MAF... typically at one of the intake tube couplings. The issue is a difference between metered airflow and actual airflow through the engine. The leak can be very small and all of the connections can seem completely secure.

The best way to check for leaks is with a can of aerosol starter fluid. Start the engine and let it idle. Spray a little starter fluid around the intake joints and listen for the engine to accelerate... when it does, you found the leak.

As indicated by Yamajee's experience with no ECU tweaking, this generally isn't a tuning issue but a mechanical issue.

The traction control light comes on is because airflow through the engine (as a virtual indication of how much power the engine is making) is a input into the traction control calculation. When there's a MAF related code, the ECU considers that input unreliable and, therefore, puts traction control into a back up mode.

Cheers

This post just helped me so much! Thanks!

I also get a P0172 periodically, and I usually just clear the code and take out the MAF and clean it with a can of MAF spray cleaner I got at AutoZone. I can usually tell when it's about to throw a code because it starts to bog from a standing start. If I clean the MAF right away, it prevents the CEL and I don't have to hassle with clearing the code. So I end up cleaning it about once per month. It only takes a minute.