AEM Wideband sensors

[redlinedeath]

how does the AEM wide band work, im a little confused, i was going to order through work (20%off, whoo!) in a few months, but dont know yet. will these replace the stock units? as in, will the stock computer read off of the new sensors, while giveing the reader an accurate reading? also, what about placement, are people using the dual channel sensor? or just one after the cat/y-pipe?

sorry, im a bit of a noob when it comes to engine management, im trying to learn, but have more questions than answers at this point!

[Johnybeas]

+1 for how wideband sensors work, I tried asking one of my auto teachers and he kinda gave me a half assed bs answer that just confused me more... I'm still not sure how this works. I'll always be one to say I'll forever be forward about something I don't know, knowledge is power, share it if you have it, don't bs it if you don't ;)

[dynomatt]

Wide band lambda meters can't run off your existing O2 sensors. The factory Subaru sensors are narrow band, and have too small a range and operate too slowly. They are really only good for running closed loop under very limited circumstances, defaulting to open loop more often. They are also known to cycle meaning they read rich-lean-rich-lean which isn't useful when you want ultra fast real time control.

Proper wide band lamda sensors will register much higher/lower mixture ranges and operate much faster. They sniff the exhaust gas measuring the amount of oxygen...because the ECU knows how much air (via the MAF) and fuel (via injector pulse length) it put in, it can reverse engineer the mixtures.

With a factory ECU (particularly where it's NA, and you can't force a lean condition by overboosting like in a turbo), the benefits of a wideband are pretty small. You can use it to monitor what the Subaru ECU is doing, but because there's no input back into the ECU that you can feed the lambda readings, you only get some numbers that you can look at or write down.

In my case, Megasquirt, as with other programmable ECU's, you can run the perfect condition. That is, set a target AFR within the ECU, then feed the wideband readings into the ECU as if it was another sensor (like TPS, CAS etc). The ECU then adjusts mixtures real time and can run in closed loop all the time. Theoretically, it's the perfect way to run an engine...reality is that a fixed AFR across the entire rev range will not develop the most power.

As a tuning tool, widebands are priceless.

[redlinedeath]

so say i went with the AEM wideband sensors, can i use these to replace my stock sensors?

[Johnybeas]

so is there a particular model or something we need to get one for the SVX???

[Crazy_pilot]

so say i went with the AEM wideband sensors, can i use these to replace my stock sensors?

With a factory ECU (particularly where it's NA, and you can't force a lean condition by overboosting like in a turbo), the benefits of a wideband are pretty small. You can use it to monitor what the Subaru ECU is doing, but because there's no input back into the ECU that you can feed the lambda readings, you only get some numbers that you can look at or write down.

I'm not sure the factory ECU would even be able to read the signals from wideband sensors. It's looking for a narrowband signal.

[redlinedeath]

ah, ok, i understand, its strictly for monitoring purpose!

[Crazy_pilot]

As far as the stock ECU is concerned, yes. With aftermarket engine management the signal can be fed into the computer and used to tune/run the car.

[Johnybeas]

So with my Hydra what do I need

[Crazy_pilot]

I'm no expert on tuning and setting up engine management. As the designated Hydra distributor, YT is probably the best person to talk to, or your tuner.

[TomsSVX]

Hydra has their own wideband sensor... It is a standard LL2 (i think) which comes with a pigtail and harness to pin directly into the ECM... You can plot your target AFR on a 32x32 load/rpm map and set up the ECM to calculate the desired duty cycle for the injectors to reach the desired AFR...

Problem is, there is so much work into setting it up, it is really just easier to tuned based on injector milliseconds... The wideband is still needed to get accurate readings

Tom