Hey there guys. Background info. I have a heat wrapped hks downpipe connected to stock twin turbos. I also have a tomei titanium midpipe and exhaust.

I have an apexi pfc and picking up a datalogit soon. Alongside this, I plan to use fc tweak and its auto tune function (which requires a wideband o2). I am aware that I can simply install a wideband o2 sensor in the place of the stock sensor, however, I am also aware this is not reccomended as a permanent install due to heat damage.

now that we are in 2024, are there better wideband options that I can run in the stock location? Or should I still weld a bung in further than the stock location? Does the heat wrapping around the area help?

I was thinking of also just a temporary install to get the wideband data logged and tuned and then put the stock o2 sensor back.

ideas guys? Thanks

 

Do not use the stock location. There are no sensors that will live up to that heat. It's not worth trying to make it work.
Most wideband kits come with a bung, so dropping your downpipe and welding one in is really quick and easy.

 

There are a lot of tuners that carry around widebands that they power off the cigarette lighter or direct from the battery and temp install the sensor. You CAN do that if you want. The best case scenario is to install the sensor according to the instructions.

It would be best to permanently install the sensor. You will absolutely need it for future use.

 

Since it's been a while since I played with FD stock twins, how far from the turbo(s) outlet is the OEM narrow band O2 sensor located?

Reason I ask is I don't think heat alone is what kills these sensors. If it were, my FD & FC should have dead sensors by now... My FD with a BW SXE300 series turbo has its WBO2 sensor located about 11~12 inches downstream from the turbine outlet, with the sensor oriented at approximately the 12 o'clock position. It's a Bosch LSU4.9 sensor that's been operating without fail for over 4 years now. I have a nearly identical WBO2 setup on my FC (BNR stage 3 turbo), same Bosch sensor location & orientation on the down pipe and that one has been running without fail since 2017 (~6 years now).

That said, from everything I've read about WBO2 sensor installation best practices, sensor ORIENTATION is probably more important that distance from the turbo/exhaust port - you never want to install one anywhere between the 3 o'clock and 9 o'clock orientation in the down pipe; in other words, the sensor tip needs to be pointing downward inside the pipe so it can easily shed any water condensation that may accumulate on its surface between running sessions. The next critical factor is your WBO2 controller and how it is setup to operate the sensor - bottom line is you don't want the controller to start sending current to the sensor's heater circuit until the engine has been running for at least 10~30 seconds after startup. That will allow the hot exhaust gasses to gradually evaporate any possible condensation from the sensor before the electrical heater circuit kicks in and potentially thermal shocks/damages the sensor before condensation can be evaporated gradually. In both of my installs, my aftermarket ECU directly controls the WBO2 sensor directly (Link G4+ in FD, and AEM Infinity in the FC), and each have settings that prevent the thermal shock scenario.

 

The instructions that came with by AEM wideband have you installing the sensor at the 9 o'clock position, but with a 15 degree uptilt. This was not done on my car and i likely burned out several sensors before I realized it. Also, I used a VW version of the sensor that matched the spec, but I suspect such sensor burned out early. I finally got my bung installed correctly, then the gauge itself quit. Oddly it was cheaper to by the gauge with the sensor than to by the sensor separately, so I ended up with some spare gauges. My bung is mounted about 8 inches ahead of the stock cat.

With the new gauge, the needle drops hard to "10" on decel. I have to figure that out. I recently cleaned by injectors, and I think the Power FC is now running rich as it was likely tuned to the dirty injectors.

 

If the ECU you're running has decel fuel cut enabled, that kind of super lean reading during decel is perfectly normal. On my Link G4+ managed FD, I'll see lambda readings max out at about 10 during decel events; on my AEM Infinity managed FC, I'll see lambda maxing out at around 19~20 during decel events.

 

i think the worry about overheating is due to the Innovate units, which would cook the sensor, and throw errors and such.
i have my NTK sensor in the stock location and its been fine.

the original plan was to tune the car, and then take the sensor out, but i keep changing stuff on the car, so its been in there the whole time, lol

 

BTW, if you need an LSU4.9 compatible WBO2 sensor that will tolerate a little bit more heat than most, an authentic Bosch part #17212 is a good choice. It's the OEM WBO2 sensor for a number of turbo diesel trucks, and after deep-diving the spec sheets, comparing it and a few other Bosch LSU4.9 WBO2 sensors, I found it has a higher operating temp range, which all other characteristics & specs being the same. This is the one I've been using in my FD for the last 3+ years. Link to it on Amazon:

 

Dropping to 10 would be running rich, no? Its like a bit of fuel dumping on decel.

The tune on my Power FC has not changed from pre-injector cleaning to after injector cleaning.

Before, I would jump above "15" on decel, now it drops to 10. *

I suspect my "cleaned" injectors might be leaking.

(* this is also leading to more backfiring, where before I had none.)

 

Maybe there was some miscommunication in my prior post - the numbers I was referencing are lambda's (L), not air fuel ratios (AFR) so an L = 1.000 would be stoichiometic, or a 14.7 AFR reading for pure gasoline. So any L reading # greater than 1.0 is considered lean, and any # less than 1.0 is considered rich. Similarly, if you're reading/displaying AFRs, numbers higher than 14.7 are lean, and numbers less than 14.7 are rich (for gasoline)

During a decel fuel cut event, you shouldn't be burning any fuel, so your Lambda or AFR reading will go way lean. The WBO2 sensor is measuring the O2 content in the exhaust, but the sensor's electrical output gets very non-linear when lambdas get much leaner than 2.0~3.0 or so, like you would have during a decel fuel cut event. So during decel fuel cut, the sensor's controller will typically display a default value like 10 or something similar when the lambda's go leaner than what the sensor can accurately measure. A difference between an L = 10 or L = 15 reading during decel might not mean anything, BUT if you're reading AFRs, a reading of 10 is very rich, while a reading of 15 is rather lean.

So is your WBO2 meter reading/displaying AFRs or Lambda values?

 

Probably worth seeing if you can add something like a copper heatsink under the sensor to give it the best chance of a reasonable life. One half cut engine several years back, with a Japanese EGT probe installed near the outlet of the turbos, had the tip bent beyond 45 degrees inside the pipe.....and must have got a touch warm.

 

The Tomei midpipe already has a bung for the o2, doesn't it? You can see it on their website photo. A lot of people on the PFC group are running theirs to the midpipe instead of the downpipe and it seems to be working well for most people.