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Backfiring and an o2 sensor question

636 Views 5 Replies 3 Participants Last post by  oldeerslayer
So a while ago i straight piped my s10, i have the 4.3l and i love the sound, although my neighbors hate it. When i did this i just snipped the o2 sensor and figured it wouldnt matter, but im not sure anymore. I did the exhaust about 2 months ago, recently after a car meet, where i revved the car a bunch, it started backfiring. That was right after a tank of gas so i figured "it must just be bad gas". Got a new tank, put some sea foam in it, and the backfiring didnt stop. Went to a shop after about a week of it and the guy there said it sounds like a bad egr. So i took off the egr and cleaned it, i thought i cleaned it well. Still backfiring issues. Today i put in a new fuel filter and it's the same story, just didn't solve my big issue. Could my past choice of cutting the o2 sensor cause the misfiring and pops? Or is it maybe just i didnt clean the egr well enough, or did i lose vacuum possibly by blowing the intake gasket? It only noticeably backfires when its at low rpm and the pedal is all the way down, and when the car is under load, doesnt do it when i have the car in neutral. Also the motor tries to stall when its in idle and shakes the whole car, it also only does this once the car is warmed up.
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A TBI 4.3 will not run right w/o a working O2 sensor. Put a new one on it.
Not saying that is the only thing wrong, but you can't diagnose the truck w/o it.
The computer sets the timing and fueling based on how much O2 is in the exhaust.
W/o the sensor it has no idea what to do.

I'm surprised a moderator didn't edit your language. This is a family friendly forum.
That comment about mileage was uncalled for.
You will need to buy a bung. Look online they are available from most speed shops.
Then just drill a hole as close to where the original was and weld the bung on. It has to be an air tight weld. If air can escape or get in the sensor won't read correctly.
Or you could cut the exhaust pipe and use a clamp on O2 bung pipe. You'll have to measure the OD of the pipe to find one the right size. They are available in most common pipe sizes. Here's a 2-1/4":

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