SES code PO420 "Help"

[2002 v6 camaro uncharged]

The SES code po420 keeps appearing and I am out of ideas. The car does not seem sluggish on take off but when it sits at idle it seems like it has a slight miss and the SES light has only come on at idle. Also, when I am driving at a constant speed I feel something like a miss, for example, if I am going 50-55 mhp in 4th gear once in awhile I will feel a chug. I just changed all the wires except one because my headers are in the way and it is hard to get to. So I will have to change that one when I have a little more time to play with it. My spark plugs should be fine since I just changed them in december. If changing that last wire does not fix the problem I have no idea what to try next. Maybe clogged injector or bad coil?
Any ideas? thanks

[ May 20, 2005, 03:58 PM: Message edited by: 2002 v6 camaro uncharged ]

[ellik]

its your headers and high-flow cat. MAYBE a new post cat O2 sensor will fix it. Most likely not. Either a Casper O2 sim, or get that code programmed out of your PCM.

[2002 v6 camaro uncharged]

Would that cause the miss firing (if that is what is going on)? I have had the headers on for a year and never had a problem and I only put the new cat on because of the code to begin with and I already tried changing all the O2 sensors. Other people have told me O2 sims will fix the problem but if the high flow cat is what is causing the code now will the cat only set the code off at idle and cause the car to chug, miss.
When I am at idle I can tell the code has come on without even looking, the car will run rough for split second and then fine again. I have gone 1 day and up to 3 or 4 days before the code will come back on.

[98Camaro3.8]

The sensor has nothing to do with it. Changing the sensor isn't gonna fix the problem.

Just get an O2 sim and be done. ;)

[2002 v6 camaro uncharged]

Thanks, but my real question is will getting the
O2 sims fix the missfire, chug and is this a problem caused by the high flow cat. Will a high flow cat make the car miss fire. You told me once that the problem with the high flow cat and the PO420 code would not affect driveability. I will get the O2 sims if it will stop the miss fire. But I just don't know if something else is causing it. Thanks for the info [img]smile.gif[/img]

[ellik]

the cat should not be causing the misfire. You probably have 2 unrelated problems.