Problem With O2 Sensors? Help Me Please

[bigj112605]

Well on my 1996 GMC Sierra 4x4 2500 with a 5.7l vortec the O2 sensors are all bad, i am trying to find a way to bypass them. Some people say to use a O2 sensor adapter while some people say to use an O2 sensor simulator.

I am coming to this point because i had the cats both back up and start fire in the cab of the truck, so i had to cut them out and go with straight pipe. The O2 sensors are running way to rich and when i come to a stop at a light then try and go it studders.......If you have any info to help me out that would be awesome Thanks

[MaForrest]

Living in California, I cant run without cats....plus the truck will run like crap. If you take the truck to an exhaust shop, they are going to want to order your cats from GM and they are almost 500$ a piece. But, a cat is a cat......bottom line. No such thing as a "high flow" cat. The only reason the GM dealership cats are so pricey is because they come stamped with a set of numbers on the bottom which a smog tech is supposed to look at to make sure they are the GM ones. Never had a smog guy look yet. So I would say to hop on ebay, order a set of magna flow cats, weld them on and replace your 02's. Truck will run like its suppose to then.

[grose67]

I agree with MaForrest. By the time you go through the hassle of bypassing the 02 sensors and everything, you could have the cats back on. You can get cheap ones at your local parts house. I dont know what type a quality they are though. I have been running the cheap ones for almost a year with no issues.

[bigj112605]

I am trying to take the O2 sensors out know and im not able to break them loose, whats the best way to take them out..... it seems like there rusted so bad that there welded on (lol)

[thearborbarber]

Get a good fitting wrench on it and rap the end of the wrench with a ballpean hammer. Be prepared to take the thread out with it. I went 50/50 on my camaro. Half came out easy half came out with the threads.

[Jsdirt]

Heat is your friend .... get them hot enough & they will come out with your hand .............. if you could only touch them.

[MaForrest]

If you are dead set to by pass your 02's, then I would say just unplug them, cut your exhaust off in front of the upstream sensor and replace it with straight pipe. Now Im not too sure how bypassing them works, but you say that your 02's now are shot right? So by even bypassing them and using somthing to trick your PCM into thinking that they are working, wouldn't you still need your 02's to work? Or is it somthing that plugs into the 02's plug that relays to the PCM?

[bigj112605]

ok so i got the 2 out after the cat, i put O2 sensor adapters in both spots, went to auto zone and had codes erased, drove great for about 10 minutes then codes came back.

 

I am first gonna fix the donuts and a couple studs for the exhaust, kinda big leak. Second im gonna replace all 4 02 sensors. and last but not least if the other two dont fix it im gonna put some cats on, cause i had them cut off about 2 years ago when one of them backed up and started a fire in the cab of the truck lol...............GOD THIS TRUCKK NEEDS HELP!!!!!!!! Ive got so much invested in this truck, i know it can be a great truck it just needs work.......

[bigj112605]

Also, thanks for your guy's help and you advice........you guys rule

[MaForrest]

If you end up putting cats back one, I would seriously consider a couple magna flows or some other brand. ALOT cheaper then dealer ones that they say you "have to use." 500$ a piece for cats is rediculious. Hope it all turns out good!

[bigj112605]

yeah im just gonna go with something cheap, im in Michigan so there is no smog testing. Im hoping that it runs great after i do all of that. I have to get two cats, i checked ebay and there around 70-80 each plus the O2 sensors are 60-65 each, i need 4 of those...... then its probly gonna cost me around 100.00 to fix the exhaust leak ( one stud on each side broke and im gonna need new donuts on each side) so to fix all of that will be around 500-600 dollers.............

[MaForrest]

I would say just head down to a local wrecking yard and get the exhaust there. The the upper peice that comes from each manifold to that connecting plate in the middle. That way your 02 holes are good to go and you can put your cats on with that peice of exhaust out of the truck. And hey, you might even get lucky and find one that has 02's in it and the cats may still be good...never know.

[redvett]

You need the front 02's for fuel control, with out them truck will run rich. Fix it right and you will have both good performance and fuel economy.

[Z'06]

Install the rear O2 sensors with spark plug defoulers and you shouldn't have any further issues with them.