JRS

It was new. I got the problem fixed. Had to program BCM with original PCM and then switch it back to "tuned" PCM Also, after market radio was causing some interference problems. I will get details from chevy service dept tomorrow.

I replaced the PCM with a tuned one from Wheatley a few years ago. No issues, works fine. I have original PCM also. I had to replace the BCM a while back. Dealer tried to program BCM, "service air bag" message and light have been on since. Dealer says he cant get message to clear. I think he programmed the new BCM with the vin of the truck. Does the original PCM need to be re-installed to get the BCM to recognize and clear codes???? Thanks,

OK, Thanks, I have seen this code several times. I just didnt know if had anything to do with the exhaust problem I'm having.

What about a PO446 code???????? Evaporative emmision vent system performance. What does that mean????????

OK, no codes Checked compression on each cyl. about 150 lbs on each. Exhaust temps look pretty consistent on each cyl also. That should eliminate the possibility of a lifter or valve. I put the truck on the lift and can hear a little noise ahead of the cat on the pass side. I still think it may be in the cat or muffler.

OK cool, The SES light is not on so I should not have any codes. If there are any old codes they would be from the vehicle that the ecm came from right??????? (I ordered a programmed ecm from wheatley and installed recently) I have been playing with a radar temp gun to see I have any difference in exhaust temps between each cylinder at the exhaust manifold. A sticking valve, lifter or worn cam lobe should show a difference exhaust temps I think. They all seem consistent. I need to remove the heat sheilds to get a more accurate reading. My next step is to get it on a rack and check the temps before and after the cats and mufflers. I noticed this morning after cranking that more condensation (it was cool) was coming from the exhaust pipe in question.

Is there any way to isolate the problem short of replacing the cats??????? I just replaced the ecm with one from wheatley but the noise was there before. so I dont know if there will be any codes. I will scan today. It looks like if there was a problem in the valvetrain you could hear it in the top of the engine.

the light has come on before but went back out after a few days. Thought it might be the gas cap loose or something that set it off.

2003 model with 31,000 miles.

OK engine guys, I have a funny sound from one exhaust pipe. Truck has dual exhaust with stock cats and turbo mufflers. It is mainly at an idle, It sounds like a flutter like it might be sucking back through the exhaust. I originally thought it might be the way the exhaust pipes were bent near the end, but now i'm thinking it might be a lifter or valve. I dont hear any noise in the top of the engine. Any suggestions on how to tell what it might be????????? Thanks,