service engine light soon is on

[bml]

Purchased an 01 gt in colorado-9000 miles. The car has a supercharger ,bigger injectors, bigger throttle body,larger fuel pump and custom burned chip. I drove the car from colorado to nebraska, ran fine till we reached my home. THe service engine light soon came on and I noticed a slight pinging or knocking. I had the computer checked and it had two codes po420 and po430 both said catalyst efficiency below theshhold bank 1 and 2. I think it had to do with the change in air from thin to thick. I also have high flow cats and 3in bassani exhaust. any help would be appreciated. bml

[powerband chaser 302]

It sounds like your cats may be clogged and need to be replaced. Since you did change altitude quite a bit you might try resetting the computer. Im not sure if its just the usual disconnecting the battery for a few hours. It might be different because of the chip. It may be programmed just for the altitude where it was. See what you can find out on the chip and go from there.

[Jeff Chambers]

Better have the tuning checked. At the Colorado altitude, there's quite a few things that would have been done for the driveability that will need to be retuned for the Neb altitude.

[P.C.]

Hi.Cat effy is usually a problem associated with a tired old converter. Clear the codes.and test drive. And try your stock h pipe.If possible. Unless the 3 inch wont hook up to it. Does it have mil eliminators. Try checking them.They plug in to the rear o2 sensors. Sounds like it may be sensing to much flow. U have a aftermarket high flow on now. So i doubt its clogged.9000 miles shouldnt clog it up.

[bml]

I tried reseting the computer and no luck. The service engine light came back on. I dont know know anything about the chip besides it was burned in Colorado. I dont have the old h-pipe. I'm going to take it to the local dyno to get the air fuel ratio checked and to see what kind of air the chip is burned for. I will take it in Tuesday or Wednesday and I will keep you guys posted. Also I didnt see any mil elimators on the end of the o2 sensors and the engine pinging or knocking has gotten worse, it only does it under load. Thanks for the help you guys. bml

[bml]

I couldnt get it in until the 15th. I was quoted a price of 500 to 600 dollars for a new chip and a tune job. I will post when I get it back. Hope everything goes well and it will be fixable. bml

[bigwhitecobra]

$600 is about the average, but why not just use a Scanner and see what the codes are? I would bet my bottom dollar you have an EGR problem. That or a random misfire. Erase the codes and see if they come back on. It's cheaper(free), and you'll know what the problem is.

If you are willing to pay $600 to fix a problem that may not even be there, I have some muffler bearings, and piston return spring that might just be up your alley.