02silvy

i have a 02 silverado 5.3/4L60 exhaust is straight out of the y-pipe other than that everything is stock. i keep throwing a p0101. ive changed the MAF, cleaned the MAF, changed the MAP, intake gaskets, cleaned the PCV system, changed o2's, new air filter, check intake for vac leaks, dropped the y-pipe (to check o2 parameters to eliminate cats as culprit), etc. i haven't eliminated the cats just yet. i think im gonna cut them out of the y-pipe anyway.

the problem occurs at about 1/4-1/2 throttle during a gear change. it causes the gear to hold a lil longer and the truck kinda "bogs" and it seems the more gas i give it the harder it bogs. this has been an ongoing problem for about 6-8 months.

this p0101 is accompanied by a p0300. the p0300 comes when the truck sits and idles. checked the missfire graph and count on a techII and its alot of missfire on random cylinders on both banks. this is what makes me think the cats could be going bad. i threw an o2 code a while back but swapped it out and that code went away.

i searched on the forum and found numerous threads about this but most problems were occuring on trucks that had tunes and mine is completely stock. at first i thought it might be because of my exhaust, but its thrown the code with stock exhaust, flowmaster, and now with the open y-pipe. thru my searches i found no conclusions as to what this could be. im about to the point of gettin a speed density tune for it and eliminating the MAF all together.

one more question. if i cut my cats off and put a pipe in place of the cats is it necesary to get another tune, or will it make it run shitty? ive heard it will run fine but throw the CEL but not to worry because the front o2's are the only ones that affect the way the engine runs.

really i just want to know if anybody has concluded what this problem may be. we searched the tech forums in GM dealerworld and nobody else has been able to pinpoint the prob either.

thanks
david

02silvy

bump.

Fireman31

Wow, you have replaced a lot of parts there. I wish you would have posted this sooner before replacing so many things. The fact that you are getting a P0300 also is almost a dead giveaway that your cats are NFG. IF you cut/gut them out, you dont have to re-tune for them, but you should to get rid of the neucense trouble codes and CEL associated with the rear 02s.....

02silvy

thats what we were thinkin bout the cats but all the parts i put on were used parts out of my toolbox that i knew were good and kept for later so i didnt spend any money except on the plugs and wires and 1 o2. ill be gettin rid of the cats soon. we were kinda concerned that the tech bulletin for the p0300 said somethin about premature valvetrain wear but were kinda skeptical on that because it wasnt just one cylinder.

454SuperSport

had something similar happen to me while tuning a truck in SD mode, it ran great except every shift felt like the ignition would cut off for a second or two. turned the maf back on and the problem went away?? you might want to dig alittle deeper into the cause of the po101, i'd be willing to bet thats the main problem.

02silvy

my truck is stock with a stock tune. think i clearly posted that up that its stock. i worked at the dealer in service so ive read and done and investigated every problem it could be, besides the cats. im not going to pay for a new y-pipe if i can just get em chopped off. im just asking if anybody else has had this code appear in similar conditions as i explained. 1/4 throttle, between shifts, hits bog and bogs harder the farther you press the gas, problem comes and goes.

ill just cut off my cats and if that dont fix it then ill just park it and let it rot.

v8

iTrader: (10)

P0300 clogged injectors, P0121 throttle position sensor reading wrong throwing a maf.

How many miles on the truck?

scooter k

iTrader: (22)

Have you checked the backpressure? That would be an easy way to determine if a cat is melted down or plugged.

02silvy

we cleaned the injectors like 6-7 months ago. i might go out there and clean them again just to check. ive been seeing alot of the hard fuel line that runs across the top of the intake, rusting and clogging the injectors lately. its got like 106k on it now but i got it at 80k last october and back then it was just the p0101 then the p0300 started showing up.

budhayes3

iTrader: (19)

Have you checked the wiring to the MAF? You may have a broken or partially broken wire, or corossion in a connector, or a pinched or shorted wire etc.