My AEM WBO2 is on the fritz. When I power cylce it the boot process goes as normal then it goes to a seemingly random AFR (usually 13ish) then slowly counts up till it goes full lean and shows nothing but 3 lines (---).

I have confirmed the sensor/wiring seems unmolested and the ground wire is good (goes to the ECU location up front under the throttle body).


Any ideas?

Also....It is powered off of a 12VDC source that switches off when the car cranks. Once I get this other issue resolved should I rewire it so it is on during cranking? I am wondering if having it calibrate while the engine is running (right after crank) is going to make it inaccurate?

Random note: The wires on the AEM WBO2 are *tiny*. It is hard to imagine enough juice to power a heater is supposed to run thru that small gauge wire.

 

mine has always done that when the engine was off. reads 14.7, then slowly goes full lean. but when the car is running, there is no problems.

 

That sounds exactly like how mine behaves. It goes through the little boot process, then displays some midrange value, and over a period of a couple of seconds, goes offscale high. Once I start the engine, it immediately settles into a nice, plausible reading.

Are you saying that this is a new behavior in an existing gauge that has been working previously, or did you just install yours are are puzzled by this behavior?


Mine is hot during cranking, though I don't think it matters. The LC1 is reported to have problems if it's fed by a wire that's hot on cranking, but I've never heard this about the AEM.

The unit does not auto-calibrate at powerup. In fact, the AEM does not auto-calibrate ever. The sensors are trimmed to spec at the factory.


Random note: In Nick Mason's composition 'The Grand Vizier's Garden Party', Nick plays all the instruments except for the flute, which was played by wife Lindy Mason.

 

This unit has been installed and working for quite some time. It was working Friday afternoon...I pulled over on the side of the road, tweaked my MS maps, started back up...it has not worked since.

I disconnected/reconnected the sensor itself...no change.

 

Ordered a new O2 sensor from Summit Racing, installed it yesterday, all is back to normal...works like a champ!