powerslide350

I have a 93 Z28 that I have converted to use four wire oxygen sensors to allow the computer to run in closed loop with the use of long tube headers.
I have not puchaced the o2 sensors yet, one because I will have to order them, and two, because I cannot decide if I should buy AC Delco's or XXX brand at the local parts store for half the price.

I have always heard there is a difference, but thats where the discussion ends. I would like to know what, if any differences are between the AC Delco's and, lets say Bosch or Delphi.

Do they send a different reading or pulse than the AC units? Do they send inconsistent readings? Are they just poorer quality? Will they cause the computer to jump in and out of closed loop?

A tech at the GM dealership told me that he thought bosch and ACDelco where made by the same manufacture. Is this true? If so then why such a difference if any?

Thanks for any and all info!

Josh.

mdacton

they are probly all made by the same little mexican or chinese boy so It probly does not matter.

shock6906

Pony up for the Delcos. You'll regret it otherwise when you're replacing them every six months. I've heard nothing but bad things about other brands' O2 sensors.

mdacton

Whats the difference in delphi and delco? I never knew.......

shock6906

I have no idea about that one. All I know is that every time I see somebody ask about how good other brands' O2 sensors are, everybody says just buy Delcos, the others are junk.

WS6T3RROR

The diff is partially the wattage of the heating elements, and the way the gaurd is made on the sensor. The delco sensor allows more exhaust gas to access the sensor itself rather than blocking everything with a shield with too few slots on it, and has a slightly higher wattage from my testing (dont recall #'s). Fwiw I have changed my cars harness and I use after cat o2 sensors from a vette on my car for front o2's. It helps with the switching correct when you have headers. Quite a big difference in heater required when you're 30+ inches from the head with long tubes compared to 6 like factory. It cured my slow idle switching problem which was making it idle all over the place air/fuel wise.

I have used the bosch sensors in the past, but i marked where the leading side of the o2 was clocked when tight in the header, and drilled/cut off part of the shield facing the flow. Then the readings were as good as the delco's, but its a risky plan for something you could avoid very easily by just getting delco's.

Steve in Seattle

Interesting... I see a similar "lazy" sensor that seems to foul sooner than the other in my headers. It's always bank 1, which has a long path in the Y-pipe to cool somewhat, while the passenger side is both tight/hot by the heads and has a short path to the collector. I wonder if it's possible to just pull the pins and swap the wires on a new rear O2 into an old front O2 connector so I wouldn't have to change the harness and still experiment with this.

Another interesting idea...

Injuneer

GM sold off a lot of their OEM parts divisions, by combining them into "Delphi" and spinning it off. Delphi became an independant company, and promptly went Chapter 11. AC/Delco and Delphi are most likely the same. The appearance of the O2 sensors that come in the AC/Delco packets appears to have changed recently, gauging by photos posted on the LT1 forum recently.

Pampered-Z

I've used both Delco and Dephi brands ( none heated ) in my 93 w/LTs and see not difference. I also have no issue with going into closed loop? Car runs exactly the same!

WS6T3RROR

What I was refering to was the switching of the o2 sensor from rich to lean. At idle it would be too slow and tend to make my car idle lean/rich periodicly and give me this HC/NOx rich soup that I found highly offensive. Not enough to throw a code, but def slow as seen in datamaster. I just put new ends on my o2 extensions so the square type would snap right in.

Steve in Seattle

Yeah, I popped some pins out of the stock O2 connectors... the pins are different.

I don't use O2 extensions on my mid-length headers, but I could make a short "dongle" to covert one style to the other without splicing the stock harness or new O2 sensors.

I was told by the guys at Speed Secrets that they use Denso 234-4012 sensors without the fouling problems GM units can have in headers. I'll give those a try if I still get fouling once we're done tuning it.

WS6T3RROR

Steve, if they're fouling the damage is probably happening during open loop operation on cold start. If your ride is cammed, lean out the open loop target afr in the area your car idles at now.

Assuming of course your blms are not at max/min values when in closed loop.

kgkern01

This is true. In the summer I bought 2 new AC Delco O2's and just recently had one go bad. Got a new one from AC Delco, and they have changed. Comes in a box instead of a bag now, have a different appearing sensor, and comes with a mini tube of copper anti-seize.

Steve in Seattle

Yeah, I had similar concerns, but we've leaned out the engine somewhat and it made things a bit better. Even brand new sensors look lazy right from the get go (in Bank 1). It's also a fairly large cam (GM 847) with large head ports... the split is laready pretty severe, and this O2 issue is driving the banks to an even larger split (on a bad day one or the other will max out.... not good at all).

Currently the Bank1 O2 sensor is just too far down stream to get clear signals and hot enough exhaust at idle/cruise to stay clean (JMO though... there is carbon build up and looks like a couple thousand miles would kill an O2 like that... the other O2 is nice and hot with a clean guard (no black cokeing). Wish I'd had a talk with the boys at Speed Secrets (local PCM/V8 guru shop) before settling for the current O2 position. Looks like I'll need to pull the driver-side header to work it out.

I was really hoping the DS O2 was close enough to get a decent signal from the other side of the oil pan, but no such luck. :/

We're gonna move the O2 sensor closer to the header (but it's gonna be a PITA... AS&M headers were NOT made to accomodate LT1 Canton Oil pans... the driver's side O2 bung points into the sump box ). I'm gonna get Speed Secrets in Monroe, WA to do some magic for me... I think there is ONE spot we can use that is close to the header/y-pipe flange but it's gonna be a PITA to weld and will require removing/plugging the Low Oil Level sensor and maybe even removing/patch-welding the one AS&M put in). ...if only Canton had welded that damn plug an inch further to the rear this wouldn't be such a tight fit.

A dry-sump Stef's pan is looking better and better all the time. :-/

1997FormulaBird

i would go for the ones with the better warrenty

i bought a pair off of summit because they were cheaper than at the parts store, but they crapped out about 6 months later.

i bought some more expensive delcos locally because they have a 1 year replacement warrenty.

the extra 10 bucks is worth the quality