Opelotus

Ok, that would make sense. Could a "clogged" O2 sensor be cleaned after being run in the exhaust stream unplugged?

Rob Edwards

Maybe, but are you going to trust tuning your multithousand dollar engine with a $50 sensor that might not be working right?

Mike Frye

Hey Glen,

I read the rule about not leaving it in unpowered as well, and I plan to install the unit permanently in order to enable me to do that but in the past 2 years since I've put mine in, it's only been powered when I was logging, which isn't very often. Since the bung locations are up on the side with the crossovers, water isn't an issue and if carbon buildup is a potential problem, I'm willing to take that chance since it's only for the purpose of the occasional logging session.

If it gets to the point where it won't calibrate after the car has been sitting for a few days (so far it has come up perfect every time I've done it) then I'll just replace it.

YMMV

ptuomov

Agreed. I was just wondering out loud about how it fails.

If you have permanently installed the sensor, why not power it automatically from the same wires that power the narrow-band sensor? I think the fuse can take it.

dr bob

The heater in the sensor isn't close to what's needed to "burn off" carbon from the "sensing element". Temperatures that high would destroy the sensor. The sensor continues to "sense" when the analyzer is disconnected, and has an accurate service life of typically 25k miles before it deteriorates noticeably. Adding the heater is a way to get accurate readings earlier in the warm-up cycle of the engine, but the exhaust stream is much hotter than the heater typically. For our sensors originally in the crosspipe, the heater helps a little, compared to those mounted in the downpipe.

Botttom line: If you want dependable readings again in a couple years when you hook up the WB analyzer again, and/or you go through a lot of start-stop cycles on the engine, plan to pull the sensor in between sessions. If you use it all the time, leave it in with the heater working. Worst case, connect the heater to the FP relay (in parallel with the factory sensor heater) and plug in the analyzer when you need it. Remember that the ~~25k mile guidance applies whether you have the sensor lead hooked up or not.

ptuomov

That's what I meant, the wires pointing down. The water flows down, not up.

ptuomov

The new Bosch sensors should go for longer than 25k miles, as they are now installed on some Audis and VWs at the factory.

The WBO2 doesn't sense (correctly anyway) without being powered, because it needs the external controller to control its air pump.

If the heater gets the catalytic reaction going inside the sensor earlier, it has to help reducing carbon build up inside the cell. That's just my conjecture.

Mike Frye

Yeah, I could do that. Right now it's completely independent of the car's systems and I'd have to hack the lead before the plug and I just didn't think it was that big a deal since I do plan to permanently install the rest of the system. It would probably be a good idea though.

123quattro

My AEM uses a Bosch (LSU 4.2?) sensor that is in production on several vehicles. That sensor should be reliable to well over 100,000 miles.

dr bob

No question that the sensors are "reliable" to 100k on some cars. The question is how long before they start deteriorating noticeably. NB sensors can be off a little and it wouldn't be noticed much while driving, but a new sensor between 25k and 50k miles pays back in more rapid response and therefore more precise fuel management. Yes, the car will pass a steady-state roll test OK, just takes longer to respond when the engine load changes. Payoff is at the pump.

blown 87

My understanding is that some how it pumps fresh air to the O2 sensor when powered, it is a very small amount, but with out it the sensor becomes clogged in short order.