So I've eaten another o2 sensor in two years. I previously posted on this issue here a while back. These are Bosch units bought through Holley. The bung is the clamp on piece that comes with the Sniper and is 10" behind the collector, 10 degrees up from parallel. It's starting to fail in the exact same way the others have where I started to notice dips in RPM at cruise and it gets progressively worse. Data logs show the AFR going full lean for a brief moment when the RPM drops. This is most noticeable at cruise with the TPS output steady. It has to be something with how I installed it. It's the only possible reason I can come up with. The headers are mid length SS if that means anything.

I've been reading around and some of the possible fixes include installing the o2 sensor into a right angle adapter to pull the sensor element out of the direct exhaust stream to help protect it from moisture build up. I'm grasping at straws here. Anyone have an idea? Thanks.

My O2 sensor is mounted at 50% to the ground and just before the collector (3 to 4 inches). The tip is into the header about 1/2 inch. Never had it failed.

Are you using the weldless install kit or did you weld a proper bung in?

I have a welded in bung! TTI headers, ordered with a 02 sensor bung.

Does your clamp on one fit snuggly?

When you pulled the old one what did the tip look like? White and chalky or black and sooty.

This is the old sensor in a new unused bung. Protrudes about 3/4" without taking into consideration the thickness of the pipe and gasket. Bung is tight to the pipe. I guess it could be sucking air, but right after replacement it was great for about 30 miles or so and then gets progressively worse until the car won't run in closed loop anymore.

You should get a bung welded into the exhaust pipe. The clamp on units never seal completely and they cause problems. Take it to a muffler shop and have them put a bung in each head pipe. Plug one and use one side. You want bungs in both sides since sometimes you need to move the O2 sensor to the other side of the engine to debug a problem.

You might also need a heat sink for the O2 sensor. I have a couple of them lying around so if you want one just shoot me a PM and I'll mail you one.

Weld a bung in. It will solve your issue.

I'll give the shop a call then tomorrow and see when they can get the in. The headers are unwrapped stainless and dump a massive amount of heat into the engine compartment. How far back you think could I get away with moving the bungs?

Thanks for helping me with this guys.

You want the bung three to four inches after the pipes connections so you get a overall reading instead of one tube.

I wish I had ordered two bungs, one on each side. I had a spark plug wire go bad on the non reading side and It took a while to figure out why it was running rich. New plug wires from FireCore solved the problem.

As others have said, I think it is leaking which is causing the O2 to fail. Your Sensor doesn't look bad, so it is probably not a rich or lean issue causing it to fail.

How many mile on the rebuild? Older motors with blow by or bad head gaskets can also lead to O2 failures.

I have heard Bosch O2 sensors are more prone to failure and should be switched to NTK but Sniper SW doesn't support it.
Only the HP and Dominator SW do.

As Andy said you need a heat sync, I use the one from Innovate , solved my problem with the Bosch sensor.

Got the bung moved up to an almost straight up position with the heatsink installed today. The gasket on the old threaded plate was blown through. Drove the car home and it was getting worse the farther I got. 250 RPM dips at constant throttle cruise and they were getting more frequent. AFR was all over the place. I guess this O2 sensor was already fragged and there was no saving it? Here goes another one.

I took a datalog of the entire 30 mile trip home if anyone wants me post any of it.

I saved a link from another member here to Ballenger Motorsports a while back. Is this the correct sensor?

https://www.bmotorsports.com/shop/p...d/1645?osCsid=6tp8hgeqirrqj33irkak5k9m84

If not I'll just pay premium and get it off of Summit.

Thanks.

If you go to the applications tab on the link you provided this is the Bosch part number they list.

0 258 017 025

Looking at the pic you provided, it may be, but I cannot see the last three numbers clearly enough on your old sensor.

Verify it.

Heh, was that you? Thanks.

Sensor is ordered. Part number matched.

Just a follow up: the sensor from Ballenger was the exact same unit from Holley. Numbers and all. It plugged right in and in the limited miles I've put on it since it's running good. Cost half as much as what Summit wants. Thanks everyone.

I hope this one last.

Yep, microsquirting a dual TBI system on my 51 Plymouth, that might ring a bell, lol.

Glad to hear it works now.