crail27 Posted February 12, 2012 Report Share Posted February 12, 2012 Ok so I have a 2004 SS & a couple of months ago my cats started making noises, then they clogged up & the truck ran horrible, throwing the p0300 code. Since my 8 year warranty ran out the week before (just my luck!), I then took them off & cleaned them out. Got it all back together, cleared the codes, & it still shakes at idle and when I give it throttle. Still throwing the p0300 & spitting fuel out the exhaust. What's funny to me is that none of the o2 sensors are throwing codes. The truck only has 50,000 miles on it...I'm stumped! Any ideas?? Quote Link to comment Share on other sites More sharing options...
Blown 346 Posted February 14, 2012 Report Share Posted February 14, 2012 (edited) That code is for a multiple cylinder misfire. Thats why your O2 sensors are fine. I would replace your plugs and wires. Make sure the spark plug gap is correct, even new plugs out of the box need to be gapped. How did you clean the cats out? When they start making noise they are falling apart inside and are garbage. Edited February 14, 2012 by Blown 346 (see edit history) Quote Link to comment Share on other sites More sharing options...
Fireman31 Posted February 14, 2012 Report Share Posted February 14, 2012 Did you have the tune adjusted for your cat delete? Quote Link to comment Share on other sites More sharing options...
crail27 Posted February 14, 2012 Author Report Share Posted February 14, 2012 That code is for a multiple cylinder misfire. Thats why your O2 sensors are fine. I would replace your plugs and wires. Make sure the spark plug gap is correct, even new plugs out of the box need to be gapped. How did you clean the cats out? When they start making noise they are falling apart inside and are garbage. Yeah I took them off and emptied what was left of them out...the passenger side only had a baseball size chunk still in it. Makes me wonder if my muffler might be clogged Quote Link to comment Share on other sites More sharing options...
crail27 Posted February 14, 2012 Author Report Share Posted February 14, 2012 Did you have the tune adjusted for your cat delete? Haven't got a tune yet, I was just wanting to get it running normal first. Not sure why the rear 02s won't throw a code with no cats.. Quote Link to comment Share on other sites More sharing options...
jm3907 Posted February 14, 2012 Report Share Posted February 14, 2012 Did you have the tune adjusted for your cat delete? You need a tune for cat delete? I thought deleting the code would be sufficient. Quote Link to comment Share on other sites More sharing options...
canadianVRss Posted February 14, 2012 Report Share Posted February 14, 2012 You need a tune for cat delete? I thought deleting the code would be sufficient. Yes, you need to tune out the 02 sensors. BUT to get full benefit of the headers you need to get air/fuel fixed. You now have better flow going out, which means you'll have better flow coming in. Adjustment is needed. Make sense? Quote Link to comment Share on other sites More sharing options...
jm3907 Posted February 14, 2012 Report Share Posted February 14, 2012 Yes, you need to tune out the 02 sensors. BUT to get full benefit of the headers you need to get air/fuel fixed. You now have better flow going out, which means you'll have better flow coming in. Adjustment is needed. Make sense? <img src='http://www.SilveradoSS.com/forums/public/style_emoticons/<#EMO_DIR#>/thumb.gif' class='bbc_emoticon' alt='' /> I knew the whole header retune for a/f thing, but what about stock manifolds with cat delete. Quote Link to comment Share on other sites More sharing options...
Blown 346 Posted February 14, 2012 Report Share Posted February 14, 2012 I knew the whole header retune for a/f thing, but what about stock manifolds with cat delete. You still need to do the same thing. Anytime you remove a cat and or 02 sensors the computer sees there is an issue with fuel metering. You will throw a code and light. Your truck will run like crap and burn more or less fuel. Which isnt a great thing. The code you would most likley thro is a Fuel/ air metering, banck 1 and bank 2 running rich or lean, or a code for the cat. Just because you dumped out what ws falling aprt in the cat doesnt mean they can be reused. When they fall aprt they are garbage and will restrict flow. Mufflers wont do this. Quote Link to comment Share on other sites More sharing options...
crail27 Posted February 14, 2012 Author Report Share Posted February 14, 2012 You still need to do the same thing. Anytime you remove a cat and or 02 sensors the computer sees there is an issue with fuel metering. You will throw a code and light. Your truck will run like crap and burn more or less fuel. Which isnt a great thing. The code you would most likley thro is a Fuel/ air metering, banck 1 and bank 2 running rich or lean, or a code for the cat. Just because you dumped out what ws falling aprt in the cat doesnt mean they can be reused. When they fall aprt they are garbage and will restrict flow. Mufflers wont do this. So getting a tune should fix the issue? Quote Link to comment Share on other sites More sharing options...
Blown 346 Posted February 15, 2012 Report Share Posted February 15, 2012 So getting a tune should fix the issue? Yes, Once you remove a cat, the cat or cats you remove wont be doing there job, the o2s will go crazy. Tuning those out will take care of it. Quote Link to comment Share on other sites More sharing options...
guineag60 Posted February 16, 2012 Report Share Posted February 16, 2012 (edited) You dont have to get a tune when you gut your cats. This is a little trick i have used on gutted cat cars of Catalyst low efficiency codes. If you go to autozone or any car parts store you can buy spark plug non-foulers. They come in packs of 2 so will need 2 packs. You cut the threads off of one non-fouler and weld that to the top of the other. Install that in to the rear o2 bung and then the o2 sensor into that. This creates a extra chamber for the exhaust to travel to the o2 sensor and tricks the reading. Or you can buy these My link . I have done this to all of my cars with out a problem until i had the money for headers/ down pipes and a tune. I currently have it done on my SSS now until my LT's, cam and converter come in and have Slowhawk tune it. Edited February 16, 2012 by guineag60 (see edit history) Quote Link to comment Share on other sites More sharing options...
f1ss Posted February 16, 2012 Report Share Posted February 16, 2012 Slowhawk is the man, along with Sir Zippy. The newbs in MA arent doing research.....guinea we have to meet up. Is the BBC or Aegean near you? Or more towards the commuter rail station? My truck is not up yet, but would like to meet a fellow veteran MA member. Sorry to go off topic guys. My fault. Quote Link to comment Share on other sites More sharing options...
guineag60 Posted February 16, 2012 Report Share Posted February 16, 2012 I live 5 min away from the Aegean. I'm no veteran with Chevy but have I been a Audi/Vw tech for 10 years. I would like to meet up too. The only member I have met from here was Jeff I believe from Maine, saw him at New England dragway when I ran Quote Link to comment Share on other sites More sharing options...
crail27 Posted February 17, 2012 Author Report Share Posted February 17, 2012 You dont have to get a tune when you gut your cats. This is a little trick i have used on gutted cat cars of Catalyst low efficiency codes. If you go to autozone or any car parts store you can buy spark plug non-foulers. They come in packs of 2 so will need 2 packs. You cut the threads off of one non-fouler and weld that to the top of the other. Install that in to the rear o2 bung and then the o2 sensor into that. This creates a extra chamber for the exhaust to travel to the o2 sensor and tricks the reading. Or you can buy these My link . I have done this to all of my cars with out a problem until i had the money for headers/ down pipes and a tune. I currently have it done on my SSS now until my LT's, cam and converter come in and have Slowhawk tune it. Cool, ill try that next. Thanks for the info guys! Quote Link to comment Share on other sites More sharing options...
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