Two weeks ago I got a CEL, got the code P0420 pulled at Autozone. Took it to the dealer and they said it wasn't the CAT, but a faulty ABS/TCS ESP lamp switch.

Around the same time, I was starting to get a slight hesitation when rolling on the throttle. It was brief and then would catch and take off as normal.

Car is 6 spd with 52K miles and has been perfect up until this. I drive it like I stole it when traffic permits, it is redlined frequently.

After reading similar posts in this forum, I pulled the MAF and it looked clean, but I went ahead and sprayed w/ MAF cleaner anyway. I also have the MS CAI. This didn't seem to make any difference.
Then I installed new plugs, coils, and some new wires from BHR over the weekend....it drives normally if I keep it under 6K rpm, but surges, bucks and hesitates if I try to rev it much higher.
I looked under the car after driving home tonight, and the CAT and exhaust system looked 'normal', not red hot in other words.

Can't find any vacuum hoses or anything else that isn't connected the way they should be....any bright ideas..I want my 'revs' back??

 

Only thing I can think of is the car is going into limp mode if the CEL is still on.

Other than that, the golden rule of thumb is if you are low on power in the upper RPM's its your catalytic converter. If you are low on power in the lower RPM's and it starts hard then you probably need a new engine.

In other words, fix what's causing the CEL first and if the problem is still there pull the catalytic converter off anyways. Also a quick search will show how many members have pulled their catalytic converter to find it completely demolished and have never had a CEL at all.

 

Not always true about low power in the upper rpms if its your cat converter. When my cat converter went i had no power down low and took forever to get going even dowhill

 

CEL hasn't come back on since I took it to the dealer 2 weeks ago.

It starts right up in the morning, and pulls fine below 5500 revs or so, unless i floor it, then it starts to bog and hesitate. Upper revs it hesitates no matter what I do with the throttle.

Oh Well, taking it back in tomorrow, I'll specifically request that they take the CAT off and look at it I guess.

I will update Friday.

Thanks

 

i went through the same thing you described. in late August my car started the same nonsense and it threw a code. i never got to find out what code it was because i don't have a code reader and i had to disconnect the battery when i was trying to change my front main seal in September. my car was parked for almost 2 months while i was away for a while. i came back and was driving the other to an appointment and it totally lost all power ... went into limp mode ... something was burning! all sorts of problems now. it must have melted some wiring or something because now it keeps blowing the "room" fuse.

now i have to find a way to get it to the dealer (a first time for me) and see whatever crap i have to go through to get the cat changed.

 

it really sounds like a CAT, I would pop your hood and push on everything and touch every hose and wire to make sure everything is connected correctly (Doing this saved my idle, my car wouldnt even stay running. Im not even sure what I pushed on that made the issue stop )

After that, if you already replaced your plugs, coils, and wires, everything is all tight and on, and the cats okay; I would DEMAND a compression test. And since all the obvious fixes have been done, they should do it.

 

I had the same issue you're talking about until I removed my MS CAI... I'm not sure how it could cause that, but I haven't had the problem since..

 

Renesis07 was right...it turned out to be the CAT. I'll get it back tomorrow and all should be well again.

I'm grateful to whomever said to insist the dealer remove the cat and visually check it this time, they said pieces were rolling around in there. Too bad it took 2 trips to the dealer to get it diagnosed correctly.

Thanks for all the input!

 

the 420 code is for a cat! you might try a dealer that has a clue.. glad you got it figured out.

beers

 

Yah, thanks to this forum I knew that when I took it in the first time. Scary that owners on this forum know more about the car than the technicians working on them!