Ok long story short, I am fairly sure that I need to replace the O2 sensors in my Bravada. I have done all the rest of the "Tune-Up" (replaced plugs, wires, cap & rotor). Two wires had abnormally high resistance causing a miss and fouled the associated plugs, the cap and rotor had rounded off electrodes with carbon buildup on just about everything.

Having Autotap'd it to take a look at the MAF frequency (chasing a hesitation problem that was there before the tune-up and got better but was still there afterwords), we also took a look at the O2 sensors, which had a slow response (long time before Closed Loop).

I have been trying to figure out what could be wrong with it seeing as how I get around 14-15mpg after the tune-up (before was 12-13mpg and it ran like crap). Everyone that I have talked to with the vortec 4.3L v6 stated that they get around 18-20mpg in the summer and 17-19mpg in the winter (possibly lower if they drove a lot in bad conditions).

Anyway, I am planning on replacing the 2 upstream oxygen sensors. I have read a lot about Bosch O2 sensors being junk, but EVERYONE around here sells them (Autozone, Advanced & NAPA). Advanced sells Bosch, Borg Warner & Niehoff Ignition. Would it be worth the extra cost to buy the Borg Warner O2 sensors or does anyone know how good the Niehoff Ignition O2 sensors are...

All listed below are OE Replacement O2 Sensors (plug and all):
Bosch 15703 = $51.88 each
Borg Warner OS820 = $61.99 each (must order)
Niehoff Ign. FE6080 = $51.99 each (must order)

Let me know - TIA

**EDIT - Oh, and everything that I have read on Autozone & Advanced Auto websites states that there are 4 O2 sensors, however, I only see 3 when I get under the vehicle...

Anyone?

So far as I've seen, the AC Delco sensors are much more responsive than any of the aftermarket narrowband ones.

For my money, AC Delco only.

Cheers,

ok yall, my .02 STAY AWAY FROM BOSCH. i went through 3 Oxygen sensors in 1 year on my 94 bonnie. I went with Delco, havent had a problem since. i dont even use bosch plugs, wires, or anything else bosch. i personally dont like the way they perform

Well, the reason I did not put in the AC Delco ones was because I really didn't want to pay the $25+ extra for them from GMPD.com, but if they are worth it, maybe I'll spend the extra coin. I really don't want to wait the 2-3 weeks for them to get here either. My experiences with GMPD.com have been HORRIBLY slow delivery... Not to mention that I get a 10% discount at all of the local parts stores.

As a comparison, GMPD.com p/n 25312200 is $62.65 each (GM List $125.29 each). The killer is the shipping & handling, which is $25.06. Now how can then charge that much $$$ when it takes the parts over 2 weeks to reach their destination?

Also, what about the other 2 I had mentioned, Borg Warner & Niehoff Ignition?

I have the Borg/Warner in my car now. The first one I bought had to be replaced within a couple of months, as it was faulty. I've had the second one in for about a year, and I think it'* starting to get sluggish. I'm ready to replace it with an AC Delco.

I've had no experience with the Niehoff. My opinion is to pay the extra and go with the Delco.

Yeah, that'* the conclusion that I am coming to, but I wanted to try to get around waiting the 2-3 weeks to get the parts. And I absolutely loathe over inflated *&h charges no matter how good of a price it is.

I ordered an EGR valve for my parents '98 STS. For the amount of time it took for the part to get here, I would have been much better off paying the additional $95 and getting it from a dealership that had it instock. Now that was a bit different as the STS wouldn't run right with the defective EGR valve. My Bravada runs decent with the faulty O2'*, but the gas mileage is suffering. I don't have to drive it though.

I can understand your position there. I ordered an O2 from them for a friend'* 00 Bonneville, and it only took about a week to arrive. Sorta surprised me that it arrived so quickly. Now, I have to get around to ordering one for mine. *&H is high, compared to a lot of other places, but the total cost is still cheaper. I do wish there was another viable alternative.

STAY AWAY FROM BOSCH NOTHING BUT TROUBLE, spend the extra few dollars and get an ac delco o2 sensor