Can running very rich damage a wideband sensor?

Here is the story. I bought an innovate LC-1 a few years back for one of my megasquirt projects. It worked great and enabled me to tune easily. About 6000 miles later that vehicle was totalled and I pulled the sensor and controller and put them on the shelf for a couple of years. When I installed it into the Fiat it kind of worked for a while then stopped with the error 8 code. So I bought a new bosch sensor and Bingo! it worked perfectly and read exactly what the dyno's sensor read The cars tune and hardware changed and with the return to the stock cam the engine started to run quite rich and then sensor readings started to go a bit wacky. It has gotten to the point now where it reads either full lean or full rich but nothing in between. I pulled the sensor and it was very sooty. On the advice of some more experienced squirters I cleaned the sensor with a little propane torch action and it started to read perfectly and allow me to begin leaning the VE table but after a day or so it went wacky again.

Can you damage teh sensor by being a bit rich? Like around 12.5 or 13 to 1?

No, you can't damage it just with that small amount of richness. Mine regularly dips below 10:1 with no complaints.

Those sensors get damaged by heat. How far down the exhaust do you have it installed?

12.5-13-1 is hardly rich. It's about right to make power, so I would say no.

I don't have any personal experience, but the guys I hang out with (one is a local MS specialist) have nothing good to say about the LC-1, and won't use one.

Yeah, the LC-1 seems to be a polarizing subject. People either love it, or hate it. I haven't had any issues with mine.

I'm not convinced this is a problem with the LC-1 yet. Sounds like a bad sensor.

I've had my Innovate LM-1 for about 8 years now. It has seen numbers as rich as 9.9 with no complaints. I can't vouch for its accuracy, but I suspect its pretty close, since I haven't blown up my turbo rotary yet, and it's not for lack of trying!

The 12's won't hurt the sensor. You might want to check your grounding, though - LC-1s work best if grounded to the engine block or battery, and tend to flake out if grounded to the sheet metal or some other locations.

I went through all the grounds when the first sensor gave me troubles. They are good. Each ground to a separate stud on the head.

The sensor is about as far away as I could get it on such a short exhaust. It is just after the collector, and as it turns out completely obscured in this photo.

That distance should be fine. I run mine about 8-9" past my turbo, which is technically too close, and i haven't run into issues yet.

Good to know. I will only be able to get about 10 inches away from the turbo when it goes in.

93celicaGT2 wrote: That distance should be fine. I run mine about 8-9" past my turbo, which is technically too close, and i haven't run into issues yet.

Past a turbo- distance isn't an issue- you've got a handy, dandy mixer there. You can run it in the turbo housing and it will read fine.

(as for the pic- you should be good to go there. If it's where I think it is based on the obscureness- it's hinted toward the outside of a bend, but 2-3 diameters from a junction is usually good enough.)

Eric

My lc1 has gone below 9:1 (where the engine actually stops firing because its so rich) many times without apparent damage to the sensor..

Now if i could just figure out WHY the car goes so rich it stalls out

alfadriver wrote:

93celicaGT2 wrote: That distance should be fine. I run mine about 8-9" past my turbo, which is technically too close, and i haven't run into issues yet.

Past a turbo- distance isn't an issue- you've got a handy, dandy mixer there. You can run it in the turbo housing and it will read fine. (as for the pic- you should be good to go there. If it's where I think it is based on the obscureness- it's hinted toward the outside of a bend, but 2-3 diameters from a junction is usually good enough.) Eric

From what i understand, it's not a problem with the reading, but rather the excessive heat and/or lifespan of the sensors.

But that's just what i understand from what i've been told. I'm no expert on the subject.

93celicaGT2 wrote:

alfadriver wrote:

93celicaGT2 wrote: That distance should be fine. I run mine about 8-9" past my turbo, which is technically too close, and i haven't run into issues yet.

Past a turbo- distance isn't an issue- you've got a handy, dandy mixer there. You can run it in the turbo housing and it will read fine. (as for the pic- you should be good to go there. If it's where I think it is based on the obscureness- it's hinted toward the outside of a bend, but 2-3 diameters from a junction is usually good enough.) Eric

From what i understand, it's not a problem with the reading, but rather the excessive heat and/or lifespan of the sensors. But that's just what i understand from what i've been told. I'm no expert on the subject.

I know Wonk just posted a handy, dandy heat sink.

And I will tell you that you don't need it, unless you are running on the ragged edge of a/f.

The following is assuming you have your O2 sensor AFTER the turbo (where it should be).

With a turbo set up, you already HAVE a heat sink- it's called the turbo. At peak power, the turbo will take out 200-300F in the exhaust stream.

So here's how it goes- pretty much all WB O2 sensors out there are good to 850C forever, 950 C for excursions- call it 1550 - 1750 F.

For you to have problems with the O2 sensor, adding up the numbers, the engine will be making 1700 - 2100 F going into the turbo. If you are doing that, few things will be lasting too long- turbo, manifold, valve seats, pistons etc (especially on older cars).

And I do have quite a bit of experience on this.

Non turbo engines are always harder on O2 sensors and heat.

Misfires can eat the sensors as well, but it does take some time.

alfadriver wrote:

93celicaGT2 wrote:

alfadriver wrote:

93celicaGT2 wrote: That distance should be fine. I run mine about 8-9" past my turbo, which is technically too close, and i haven't run into issues yet.

Past a turbo- distance isn't an issue- you've got a handy, dandy mixer there. You can run it in the turbo housing and it will read fine. (as for the pic- you should be good to go there. If it's where I think it is based on the obscureness- it's hinted toward the outside of a bend, but 2-3 diameters from a junction is usually good enough.) Eric

From what i understand, it's not a problem with the reading, but rather the excessive heat and/or lifespan of the sensors. But that's just what i understand from what i've been told. I'm no expert on the subject.

I know Wonk just posted a handy, dandy heat sink. And I will tell you that you don't need it, unless you are running on the ragged edge of a/f. The following is assuming you have your O2 sensor AFTER the turbo (where it should be). With a turbo set up, you already HAVE a heat sink- it's called the turbo. At peak power, the turbo will take out 200-300F in the exhaust stream. So here's how it goes- pretty much all WB O2 sensors out there are good to 850C forever, 950 C for excursions- call it 1550 - 1750 F. For you to have problems with the O2 sensor, adding up the numbers, the engine will be making 1700 - 2100 F going into the turbo. If you are doing that, few things will be lasting too long- turbo, manifold, valve seats, pistons etc (especially on older cars). And I do have quite a bit of experience on this. Non turbo engines are always harder on O2 sensors and heat.

Interesting and good to know, i appreciate the explanation.

So the old adage of "Twelve inches past the turbo" is more of an old wives tale than anything?

And yes... 1700F EGTs is usually the signal of things not good.

Paul_VR6 wrote: Misfires can eat the sensors as well, but it does take some time.

You mean like a lot of raw fuel hitting the sensor?

So say if you had a siamese port engine with a cam with a large amount of overlap and for every exhaust cycle it steals a percentage the other cylinders charge of fuel and air and sends it out the exhaust unburnt? Because that is exactly what was happening until last weekend when I pulled the cam.

93celicaGT2 wrote: So the old adage of "Twelve inches past the turbo" is more of an old wives tale than anything?

I know on my old XR4Ti the narrowband O2 was in the downpipe casting less than 3 inches from the turbo.

ditchdigger wrote: You mean like a lot of raw fuel hitting the sensor?

liquids are deadly to sensors. Since the thimble is basically ceramic- they break pretty easy when liquids are sent at them.

93celicaGT2 wrote: So the old adage of "Twelve inches past the turbo" is more of an old wives tale than anything?

For the most part.

Perhaps it's the liquid from misfires that started the tale? dunno.

I know my production UEGOs are just a few inches from the turbo outlet.

Eric

Yes. I drag race and I'm on the spark cut limiter all the time and need to recal the sensors a good bit and replace them once a year, period.

alfadriver wrote:

ditchdigger wrote: You mean like a lot of raw fuel hitting the sensor?

liquids are deadly to sensors. Since the thimble is basically ceramic- they break pretty easy when liquids are sent at them.

93celicaGT2 wrote: So the old adage of "Twelve inches past the turbo" is more of an old wives tale than anything?

For the most part. Perhaps it's the liquid from misfires that started the tale? dunno. I know my production UEGOs are just a few inches from the turbo outlet. Eric

I guess that's possible as well... and maybe a concern with me, but that would be the same no matter where i put the sensor in my case. When i'm blowing fireballs 6 feet past the end of the exhaust, i'd be fighting a losing battle.

Like Paul, i'm sure when i get the "two step" up and running, i'll have to replace sensors fairly often. Probably turbos as well.

sounds like a cool project.. but I am not sure I would want to replace parts quite that often

Once you get the tune down, you can pull the sensor, and plug the hole.

Paul_VR6 wrote: Yes. I drag race and I'm on the spark cut limiter all the time and *need* to recal the sensors a good bit and replace them once a year, period.

Honestly? If you are breaking sensors once a year, you are doing something wrong. They are not that sensitive.

Shift earlier or raise the limit? Why are you bouncing off any limit for any amount of time?

But if you are happy with the cost of swapping them, go for it....

Eric

alfadriver wrote:

Paul_VR6 wrote: Yes. I drag race and I'm on the spark cut limiter all the time and *need* to recal the sensors a good bit and replace them once a year, period.

Honestly? If you are breaking sensors once a year, you are doing something wrong. They are not *that* sensitive. Shift earlier or raise the limit? Why are you bouncing off any limit for any amount of time? But if you are happy with the cost of swapping them, go for it.... Eric

2step launch control and/or no-lift shifting.

93celicaGT2 wrote:

alfadriver wrote:

Paul_VR6 wrote: Yes. I drag race and I'm on the spark cut limiter all the time and *need* to recal the sensors a good bit and replace them once a year, period.

Honestly? If you are breaking sensors once a year, you are doing something wrong. They are not *that* sensitive. Shift earlier or raise the limit? Why are you bouncing off any limit for any amount of time? But if you are happy with the cost of swapping them, go for it.... Eric

2step launch control and/or no-lift shifting.

Which isn't that much different than our fuel/spark traction control.

And how does no lift shifting hurt anything? You should be doing it fast enough to not over-rev the engine, right?

You might be surprised the abuse these things were designed to take. That's why I'm wondering what in the world you are doing to actually break them.

it almost sounds like it's physically breaking them, not via the exhaust path....

alfadriver wrote:

93celicaGT2 wrote:

alfadriver wrote:

Paul_VR6 wrote: Yes. I drag race and I'm on the spark cut limiter all the time and *need* to recal the sensors a good bit and replace them once a year, period.

Honestly? If you are breaking sensors once a year, you are doing something wrong. They are not *that* sensitive. Shift earlier or raise the limit? Why are you bouncing off any limit for any amount of time? But if you are happy with the cost of swapping them, go for it.... Eric

2step launch control and/or no-lift shifting.

Which isn't that much different than our fuel/spark traction control. And how does no lift shifting hurt anything? You should be doing it fast enough to not over-rev the engine, right? You might be surprised the abuse these things were designed to take. That's why I'm wondering what in the world you are doing to actually break them. it almost sounds like it's physically breaking them, not via the exhaust path....

From what i understand, and how i've always set up no-lift shifting, is that i would set a rev limiter between gears with the clutch in that was actually slightly lower than the redline.

Unless you're superhuman, with a fast spark cut limit, you're going to bounce it once or twice every shift.

Over-revving the engine itself (at least as i understand it, but i'm open to education) won't have any negative effect on the sensor. The issue is the misfires when spark is cut, upon engagement of the limiter. Misfires generating more heat and/or more fuel, extra stress on the sensor.

That said, i really have no idea exactly how much stress one of these sensors is SUPPOSED to withstand.

I haven't had issues with mine yet, but then again, i've only driven this car about.... 4000 miles, nor do i have any sort of spark cut limiter or no-lift shift programmed. I doubt my transmission would withstand no-lift shifting. Mazda can't make a strong FWD transmission to save their lives.