TN94Z

iTrader: (14)

I know this question is about a truck. I posted this on the truck board too but I wanted to stick it in here too because I need a response as soon as I can get one. My friend just had a y-pipe installed and a magnaflow muffler on his 02 Silverado. Now his truck pops bad when he goes wide open throttle like the fuel is being killed to the motor. I think this may be a side effect of what I am about to tell you. When I scanned his truck, his Ltrims are all RED and on the gauge display his Ltrim gauge was completely red and not giving any reading at all. In the histogram, the pcm was adding like 18-20 of fuel. In the DTCs table I got an O2 error that said something about not enough activity or something...can't remember for sure. What do you guys think? Does it sound like bad O2s or an air leak or something? I have never seen this much RED when I looked at a scan. Thanks in advance.