auricomXL

i was using an inovate motorsports LC-1 wideband O2 with megasquirt. the thing seemed to be working fairly well, aside from some annoying spiking which i attributed to some leaks in the exhaust. recently the readouts have been stuck around 7.4:1 AFR, which i knew was incorrect given the way the engine was running just fine. i looked at the warning light which is normally hidden from view and noticed error code #8, which according to the manual is a damaged sensor due to excessive heat i believe. I pulled the O2 sensor out, pluged the header with the bolt, tuned on the accessory switch, and hit the recalibrate button for the wideband. this had limited results. we were able to get a reading of about 22% which is close to being correct in the open atmosphere, however when we first got the sensor, the output would move around when one would blow across the sensor. this time around, the sensor was not very responsive. we put the sensor back in and it still was reading bogus values. occasionally the wanring light would stop flashing and it would read that the sensor was working, even while it was still stuck at a readout of 7.3:1 AFR.

during instalation, we tried to follow the instuctions as well as possible. before anyone asks, i will tell you what we did to prevent damage by following instructions:

there is no turbo, so the O2 is mounted in the header.
there is a muffler on the vehicle but no cats or anything so backpressure must not be too large
we did not mount the sensor below the 3 o'clock to 9 o'clock position (as directed)
we did not run the engine without the sensor's heater line pluged in (as directed)

the only thing i can think is that we were getting some low voltage codes out of the sensor when our megasquirt battery was getting low. maybe we ran the engine too much during these conditions and the O2 heater could not keep it hot enough.

the other thing is the effect of the pre-mix oil on the sensing element. anyone run into similar problems with pre-mix and an O2 snesor?

is there anyway to "repair" or "clean" somehting on this sensor or am i just going to have to spring for a replacement?

if so i will make sure to relocate the O2 warning light to a location easily seen next time around.

scrip7

iTrader: (6)

Do you have pics of your header where the sensor is mounted? sometimes it is necessary to weld a threaded bung and install the sensor a little bit further downstream to reduce the heat load on the sensor/ controller. Sounds like yours bit the dust.

gross polluter

Sounds like a dead sensor. I'd suggest placing the sensor farther back in the system, the headder I'd imagine is still too close on a rotary. On my turbo II, I had to locate the sensor under the passenger seat to get readings that were not erratic.

auricomXL

wow, i didn't think i should copensate for the rotary heat that much! i guess it makes sence though.

the headers on the car are actually just test headers while the engine is out of the car. they come out about a foot, then angle forward and are ducted out of the garage. the O2 sensor was basically about 1 foot from the motor, on a straight piece of pipe, no bends between the motor and the sensor. this must have been the problem. we have a thermal couple plugged in right near that spot. can anyone suggest a safe operating range for the wideband so i can pick the best place for the next one?
thanks guys

toplessFC3Sman

iTrader: (1)

I have my sensor at least 4' from the manifold. This is on a turbo, but its in the middle of the pipe between the downpipe and main cat. Also, the sensor should be above the 9-3 position so that condensate/water cant collect around it when you shut the engine off and the exhaust cools down. Id move it back and rotate it (well, do that with a new sensor, that one is shot)

scrip7

iTrader: (6)

What kind of exhaust will you be using in the car? is it turbo or NA?
It is supposed to be mounted a minimum of 12 inches from the start of the downpipe. I would prefer a bit more, such as a minimum of 16 inches. I would also suggest not mounting the sensor in a straight up position (likely no room to do it anyway). Keep it at 2 o'clock or 10 o'clock on the pipe if you have room, or 3 and 9.

EDIT: Looks like I got that one in right after topless.....sorry for the redundancy

muythaibxr

Innovate makes a heat-sink extender bung for those who don't want to mount the sensor way down the pipe. A friend has used one of those for quite a while on his S4 NA in the stock sensor location and has not had any problems with the sensor itself.

He did have a problem where the analog outputs on the LC1 fried though.

Ken

auricomXL

thanks for all the info guys, though this sucks about a replacement sensor ($80!) i guess sometimes one has to learn from ones own mistakes though.

also, the engine is an NA S5, and it's got a bizzare exhasut system on it right now, as we just fabricated some make shift headers for testing purposes. the engine is not in a car right now, and there is no way it would fit with the current headers. that said, we might start hooking up the turbo this weekend so that we can start really tuning the engine as it will be in the car. when we do this we will fabricate the final design headers. the turbo is pretty sweet, it a bran new twin scroll Borg Warner that i got from work. it's the smallest turbo that we have here, but i still fear its a bit oversized. the only other turbo's i have that are new are from 14 liter diesel engines, and it would be pretty stupid to put that on the rotary.

i'm pretty excited about the twin scroll though. i've got an extra turbo that is the exact same model, and we are going take it and turn it into a turbine engine using only one of it's scrolls (the other blocked off). after we do some testing on it and get it working well, we will combine this system with the rotary and run one scroll of the turbo as a closed loop turbine engine for our anti-lag system, and the other scroll will recieve normal exhaust gas from both rotors...thats the plan at least.

auricomXL

i just talked to a guy from Inovate motorsports. i asked him if i should worry about problems with the O2 becasue of the oil in the gasoline. he said i can "think of the oil like leaded gas, sensor degradation will happen a lot faster". have you guys run into problmes with this at all? i have been mixing my gas with a generous amount of oil: i usually do about a 110:1 ratio, is this too much?

I'm beggining to ponder just using one of the narrowbands i have laying around to do the BASIC tuning, then putting a new wideband on only after i have everything running well. does this really make setting up the tables much harder? i mean, even with the wideband, i am pretty much just looking to see if i am too rich or too lean, knowing by exactly how much i am rich or lean is just kind of a "bonus". Won't a narrowband achieve the same effect?

scrip7

iTrader: (6)

Sounds interesting. Looks like you have put quite a bit of thought into your system. Keep us posted on how well it works.

muythaibxr

The narrowband is only accurate at 14.7:1... so while you can tell rich or lean, you won't be able to tune for maximum power or safety with just a narrowband.

Ken

gross polluter

I have not seen many posts here "my WBO2 only lasted 1000 miles WTF?" I personally have roughly 5k on mine, about 10 months old, and have no problems. I'd agree that the sensor degrades quicker, yes, but what are we talking about here, 10k instead of 40k miles?

muythaibxr

I think with a small amount of premix, the O2 sensor should last just about as long as it normally would. Maybe slightly less time, but I'd be surprised if it died after a few hundred miles, or even a few thousand.

Too much heat will kill it though.

Ken