2002 silverado 5.3L Misfiring

I bought an 02 silverado extended cab with a 5.3 liter in the summer of 03. At first i did notice some smoke out the exhaust at start up but the smoke went away after the first month. I was told this problem could be my Valve seals. Now i have a bigger problem. In 04, before i left to be stationed in korea, I noticed loss of power at certain times while driving. I left my truck in storage for the year i was gone. now that i am back my truck is now starting to misfiring alot. it is more noticeable now since i put a flowmaster exhaust on my truck. it usually back fires and loss of power upon exeleration. I have changed my fuel filter, plugs, air filter, oil, and exhaust. My instrument panel shows no warning of any problems with my truck. i have yet to have someone read any codes it may have stored in the computer. I just want to find out what this could be, anyone have any idea??? any info would be greatly apprieciated.

Your catalytic converter might be pluged up. Best bet is to go to Autozone get them to read the codes.:2cents: :2cents:

I was going to drive my truck from phoenix to texas for vacation but with this problem i didnt want to chance it. when i get back next week i will take it to autozone and get my truck read. How much does this cost? I was going to take it to the dealership but wow...they cost alot, but i will try it, hopefully that is where my problem is and nothing more. thanks alot for the help.

Do not take to AutoZone(really called AutoJunk) to get the codes read,the person checking the codes are not trained into computer work..Go to someone that has a scan tool instead of a code reader.A plugged catalytic converter will kill a 5.3 and I have seen this happen.You can get the cat from the dealer only,there is a core on the old catalytic converter(the whole front exhaust in one piece) from the dealer and it is not available from the aftermarket.It is covered under warrenty,8 years up to 80,000 miles.

go to any place that sells walker exhaust parts. they will have cats for your truck and at half the price of gm. i put these on my truck a year and a half ago and every thing is fine.

When i get back from vacation I will check with someone to see what codes are in my computer. Hopefully it is the cat and i can take it to the dealer and have it replaced for free since it has an 8 year warantee. I have replaced my mustangs cat for the same reason but on my mustang the engine light came on all the time. Ford replaced it for free since the cat was still under warantee. Thanks for the info though. I really dont want to spend $$$ if i dont have to.

Well I took my truck in to Midas so they could do a full diagnostic on my truck. Come to find out the plugs I have been using for the last 3 years are crap:banghead:. I was using Bouch Platinum plugs which are not for my truck. The technician removed the somewhat new plugs i had put in during 2004 prior to leaving the truck in storage for 2005 and found the plugs nearly toast. I had no codes stored in my computer nor any engine light. I just replaced the plugs with new AC-Delco Iridium plugs @ 6.99 each, but was worth it. My truck runs and sound like a champ now. My fuel economy is now at about 18-19 miles per gallon in the city from the 15-16 i was getting. I just went ahead and also changed my wire set and fuel filter just to be on the safe side.

Well I took my truck in to Midas so they could do a full diagnostic on my truck. Come to find out the plugs I have been using for the last 3 years are crap:banghead:. I was using Bouch Platinum plugs which are not for my truck. The technician removed the somewhat new plugs i had put in during 2004 prior to leaving the truck in storage for 2005 and found the plugs nearly toast. I had no codes stored in my computer nor any engine light. I just replaced the plugs with new AC-Delco Iridium plugs @ 6.99 each, but was worth it. My truck runs and sound like a champ now. My fuel economy is now at about 18-19 miles per gallon in the city from the 15-16 i was getting. I just went ahead and also changed my wire set and fuel filter just to be on the safe side.
Many people have learned this lesson with "Botch" plugs.

I had the same problem with my 99 Gmc changed plugs and all was well for a short time. it turned out to be the plug wires. it took me a LONG time to find the problem. It was very noticeable at low RPM high load(just before a downshift). Try some die electric grease on botth ends of the wire it should buy you some time.

Glad all is well, just curious how you are getting that kind of milage on your 02 Silverado. I get quite a bit lower than that and I believe all is in good shape.

Thanks,

Scott