V6 vortec. Its only throwing p0420 code. But only after hollowing out my converter. It was misfiring/bogging down before I did it too and throwing no code, which is why I hollowed out the converter thinking it was clogged up, but that did nothing either, so now its throwing the code and still occuring. Took it to a local shop they said to replace the cap and button and it should fix it, it seems to stop the misfiring and bogging down for about 4-5 days and was running perfect, so I thought it was the problem. But now its doing it yet again running like ass. Seems to only occur when pressing throttle through first and second gear (in auto trans) once I get it to third shift(gear) it smooths out and runs ok with very little to no bog down. Seems I have to ease the throttle to get it to not do it, but its when I press hard on the pedal it doesnt want to go, or if it does bogs down and sputters. Hope this info is a little more helpful. Thank you.
April, 4, 2012 AT 7:16 PM
Oh also to mention the local shop smoked it out (vaccum) and checked my fuel preassure and those all tested out fine. For some reason im thinkin it could now be injectors not fuelling correctly/clogged, or maybe fuel pump not pumping the right amount of fuel into the engine when I press on the gas pedal? Not sure what it could be though. Also tried sea foam but that did absolutely nothing either.
April, 4, 2012 AT 8:35 PM
Did you use good quality ignition parts? Auto store house brand is crap generally. So that has spider/poppet injection?
April, 4, 2012 AT 8:36 PM
What about MAF/MAP sensor? How do plugs look?
April, 4, 2012 AT 8:45 PM
It looks fine I even checked inside to see if gunk was built up in the connectors. I have tried everything mechanics have reccommended and still no fix for it. It also seems like it ran better for about a week after I put the new plugs in too, but started up doing it again. I used ac delco parts, except for the plug wires, they were like in a black box with purple at the top.