So, my car is showing so real bad hesitation, but only whens its lukewarm. The problem is not there when cold or when fully warmed. However today comming out of the gym I started it up and the needle was at "C", but higher than the normal cold start sub C position. As I hit the gas it stumbled and puttered. Then it was fine. I parked the car and then about an hour later went ot go pick up some Chinese food..same thing while comming down the driveway. I turned onto the street and all was well again.

What gives? This has only started since replacing the Y pipe(and hesitated as I pulled out of the muffler shop). O2 sensor damage? I don't have any MIL light, but even if the O2 sensor was bad, but still pluged in it probably wouln't throw a code.

 

Did you leave the battery unhooked after you had th y installed. I know sometimes the ecu has to reset although I wouldnt think it needs to on a y especially since you already had a performance y on.

the other thing I was thinking is what you said and the shop messed up the o2 sensor.

 

sounds like the o2 to me

 

Maybe the problem will fix itself...hehehe. But really, pre-install, I had driven 215 miles in one day, less than the first half tank of gas used! So I know my MPG were great, 24 hours prior to the install.

 

when i got my y-pipe installed at a shop, about a mile later my battery light and brake light came on and i was idling at about550 rpm and the car would almost die. i figured it was my alternator so i bought a new one and changed it. i had two shops tell me my alternator was bad, i believed them. after i spent the money to buy the alternator and spend the time to install it, the same thing was happening. took it to the dealer and they told me that my o2 sensor was bad after they had checked all my wiring from my stereo system. took them the whole day to figure it out.

took the wrpspd y-pipe off and put the stock one on with a new o2 sensor. works great. i will attempt to put the y-pipe back on as soon as it gets a little warmer.

my car hesitated a whole lot. check your o2 sensor. hows your mileage after the install. good luck finding the problem.

 

my $.02...

there's prob some "gunk" (technical term) in the pipe that needs to be burned off. your O2 probably is picking some of that stuff and making the car a little "off"?? give it some time and see if it gets any better.