chawkins6789 Posted February 3, 2013 Report Share Posted February 3, 2013 What is the most likely cause. Random misfire, not cylinder specific. I failed my emissions test because of this. it happens about once a week and usually goes away after a 45 minute drive. But It pops at the wrong times. After I change this exhaust I need to fix this so I can pass emissions. Where do I start looking? Quote Link to comment Share on other sites More sharing options...
texaSS364 Posted February 3, 2013 Report Share Posted February 3, 2013 I got that code when I changed out my headers, ended up being a cracked spark plug. but that doesn't sound like the case for you. Quote Link to comment Share on other sites More sharing options...
chawkins6789 Posted February 3, 2013 Author Report Share Posted February 3, 2013 The engine has about 35k, the rest of the truck has 113k. The MAF, manifold, emissions equipment came from the 4.8. Quote Link to comment Share on other sites More sharing options...
The_aSSet Posted February 3, 2013 Report Share Posted February 3, 2013 Is it cammed? Quote Link to comment Share on other sites More sharing options...
chawkins6789 Posted February 3, 2013 Author Report Share Posted February 3, 2013 No. All thats done to it is a tune, CAI, and cat-back Quote Link to comment Share on other sites More sharing options...
The_aSSet Posted February 3, 2013 Report Share Posted February 3, 2013 Check your plugs and wires I'd say first Quote Link to comment Share on other sites More sharing options...
Aldofashow Posted February 4, 2013 Report Share Posted February 4, 2013 Check the temp be for and after your cats both will be hot be for if one is colder after then that's the one that clogged that happened to me Quote Link to comment Share on other sites More sharing options...
chawkins6789 Posted February 4, 2013 Author Report Share Posted February 4, 2013 Will a cat cause a misfire? I have a replacement on the left side. Put in about 8 months ago. The right is original. Factory 5.3 y-pipe. Didn't have this issue with the 4.8. Only after the 6.0 occupied its place. Sent from my DROID RAZR MAXX using Xparent Red Tapatalk 2 Quote Link to comment Share on other sites More sharing options...
kelleyperformance Posted February 4, 2013 Report Share Posted February 4, 2013 (edited) yes a clogged cat will absolutely cause a miss. like said above, change your plugs and wires first- it wont hurt either way and is most common issue. then, buy some MAF cleaner at auto parts store, clean off the MAF element, clean your TB with throttle clean (not brake cleaner, can mess up coating on TB plate), and last id check that cat out. if you can remove the y pipe and visually see down the pipe to see cat element, do that. if you cant, hit it with a rubber mallet and check for a loose sound/rattling sound. that indicates a bad cat. also, i find that the tune can be a culprit MANY times. i have no experience with who tuned your truck. if you have access to HP Tuners your welcome to email me your tune, id be happy to check it out Edited February 4, 2013 by kelleyperformance (see edit history) Quote Link to comment Share on other sites More sharing options...
chawkins6789 Posted February 4, 2013 Author Report Share Posted February 4, 2013 I have to get SSS cats to pass emissions anyways. I can't imagine plugs going bad at 35k. I thought about the maf Sent from my DROID RAZR MAXX using Xparent Red Tapatalk 2 Quote Link to comment Share on other sites More sharing options...
kelleyperformance Posted February 4, 2013 Report Share Posted February 4, 2013 its not that i think a plug "went bad", it could have fouled from internal issue, have a small crack, wire could have high resistance/small tear not visible... im just trying to help you here, this is usually the case on a low mile car in good shape with a random miss. you have stock wires and plugs? Quote Link to comment Share on other sites More sharing options...
Aldofashow Posted February 4, 2013 Report Share Posted February 4, 2013 Use a hand held lazer temp gauge and check those cats I didn't hear anything in the pipes just random miss fire I bought new coils wires plugs and it was my drivers side cat clogged up solid I was limping all the way to the shop he checked the cats and sure enough jammed we hollowed both cats and free flows now Quote Link to comment Share on other sites More sharing options...
desrtrat Posted February 4, 2013 Report Share Posted February 4, 2013 (edited) what were your HC/CO readings. did they clear the code and retest, or just fail you on that..i would also check your fuel pump, and regulator for any irregular pressure reading drops. a slight drop in fuel pressure can cause a lean misfire. as stated above, have your tuner check his work. maybe he went a little to aggressive.. good luck edit..how is your fuel filter? new, been a round a while? Edited February 4, 2013 by desrtrat (see edit history) Quote Link to comment Share on other sites More sharing options...
kelleyperformance Posted February 4, 2013 Report Share Posted February 4, 2013 what were your HC/CO readings. did they clear the code and retest, or just fail you on that..i would also check your fuel pump, and regulator for any irregular pressure reading drops. a slight drop in fuel pressure can cause a lean misfire. as stated above, have your tuner check his work. maybe he went a little to aggressive.. good luck edit..how is your fuel filter? new, been a round a while? he doesnt have an external regulator, he doesnt have a fuel filter (GM... ) the fuel pump regulates the fuel pressure, its a returnless system so it kinda eliminates that issue. they pretty much either die or work, almost never in between. Quote Link to comment Share on other sites More sharing options...
Aldofashow Posted February 4, 2013 Report Share Posted February 4, 2013 I've gotten 4 stickers with the hollow cats I think he shut o2 off after the cats temp fix all new exhaust coming Quote Link to comment Share on other sites More sharing options...
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