Wideband going nuts? Funky readings

[podium]

My wideband was working perfect before. I upgraded my fuel pump and redid the lines in my corvette. Set fuel pressure to 58 and good to go. After I had every thing back together I was going to tune it since the fuel trims were off due the line/pump change. Well, my wide band started going nuts. Reads lean on first start up and always lean when I get on it. It will go lean and then super rich then back to lean or hover around lambda. I put the wideband on my 05 silverado and it read "air" or "lean" at idle just like the vette. I used a different sensor and used the tail pipe adapter. I thought for sure the plx was bad. I ordered a AEM 30-0300 and itsa doing the same thing. There is no exhaust leaks that I can tell and everything is tight. Could this be a bad ground? Could it be the power source? Sometimes I even rev it to 4k lightly and it goes lean and takes a a few seconds to read lambda again. even a blip of the throttle will do this.

Any thoughts?

I included a log.


It didnt have this problem before I swapped to a 8 an line and added the return. Fuel pressure is nice and steady

[cobaltssoverbooster]

Check batter cable connections, grounds, and test the voltage regulator. My wideband switched from 18-12 when cruising because the voltage regulator decided to stop working.

Did you ever fresh air calibrate the sensor?

[podium]

Interesting. I have not done the fresh air calibrate. I dont think the plx or the AEM needs it but I could be wrong. I was thinking of doing a new, independent ground for the wideband. Reading the same on 2 cars tell me its the wiring.

[podium]

Well, I did the brake cleaner in a rag test and BOTH of the sensors I had failed. One of them wouldn't even move while the other flinched a little and went lean as soon as it it was in the rag. I did by a new AEM wideband and that senor passed easily. My other two sensor do not have much time on them at all. One sensor has only been in a car for a few thousand miles and the other was only use for WOT tuning on about 4 cars.

[cobaltssoverbooster]

fresh air calibrate is critical. Innovate and AEM have re-calibration procedures because of sensor degradation. For these disconnect the sensor and turn on until gauge throws an error code. turn off system for 30 seconds and reconnect sensor lead. now turn gauge on with sensor in fresh air and it will re-calibrate upon warm-up.
for the PLX you have to follow the test procedures which has a 30 second warm-up cycle included which is the units "calibration and pre-heat phase".

PLX Test:
1. The output is not showing the correct AFR readings:

A. With the O2 sensor harness disconnected, at initial power-up it should display between 14.6 and 14.7(wideband analog voltage: 2.30V - 2.40V).i. If it is reading below 14.5, please verify that the unit is receiving at least 12V and you have at least a 5amp fuse. If it is still reading below 14.5 even with the correct voltage, contact [email protected] andrequest a RMA number. Your unit is faulty and needs to be repaired.ii. If it is reading above 14.8, contact [email protected] and request a RMA number. Your unit isfaulty and needs to be repaired.

B. Reconnect the O2 sensor with the sensor harness, with the O2 sensor exposed to free air. During the 30 second warm up phase, the voltage should increase from 2.35V to 5.0V.i. Voltage does not read 5.0V even after 60 seconds:a. Try another power source for your SM-AFR.b. Verify that a fuse is installed rated no less than 5A.c. Check connectivity of harness and O2 sensor.d. Your O2 sensor needs to be replaced.

C. When the unit says AIR*, blow on the O2 sensor. The display should show LEAN*.i. Display does not go to LEAN*: a. Your O2 sensor needs to be replaced.* will only show “LEAN” or “AIR” on DM-6 Gauge

[Badazzsi]

Did you ever figure this out? I know a very old thread but mine is doing basically the same thing. i have already replaced the sensor 1 time and i dont even have a couple thousand miles on the current one. maybe its the gauge or the fact that i have the sensor after the hollowed out cat on the driver side. was thinking its time to pull that header and have a bung welded in the proper location for proper readings for the AFR gauge

[Evo8john]

I have noticed that with a lot of controllers (Haltech, AEM, Innovate specifically) if you leave the gauge/sensor on without the engine running it seems to kill the sensor much quicker. I have customers that have lost brand new Bosch sensors in less than 500 miles due to extended periods of key-on engine-off while setting other things up on the car, or just forgetting the key/accessory power was on. Just something to keep in mind.

[dr.mike]

Leaving the sensor powered up, for long periods, in the open atmosphere, will degrade the sensor. But, that takes a good while.

Leaving the sensor un-powered in a running exhaust will, also, degrade the sensor, over time. But, again, this takes some time.

What can kill a sensor, in short order, is to let the sensor power up, before starting the engine. When the sensor is powered up, its CERAMIC element is heated up to about 1400?F ( glowing orange hot ). This happens within a few seconds of turning the wideband power on.

When the engine is started, there is an initial rush of cold exhaust gas. It is, often, accompanied by condensation ( water ). This rush of cold/wet air will fracture the sensor element, if it hits an element that is already hot.

OEM ECUs are smart enough to not start heating the wideband sensor until the engine is already running. But, aftermarket widebands, generally, do no know when the engine is running. ( I am working on that )