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ngc1068
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Last seen: 5 months 1 day ago
Joined: 08/28/2019 - 16:26
AEM Failsafe Wideband 30-4900 reported AFR error

Hi, I have a 30-4900 failsafe wideband.  I am only using the AFR, boost and RPM inputs.    When my car is idling warmed up (running off the narrowband sensors in closed loop), I notice that the AFR reading stays around 14.2.    I recently obtained the AEM X-Series wideband for my other vehicle (and to use with HP Tuners) and decided to try it on the subject car with the 30-4900.   The X-Series unit reads between 14.6 and 14.8 (as expected in closed loop).   I purchased a brand new LSU 4.2 sensor for the 30-4900, expecting it to begin reading like the X-Series, however it still reads around 14.2.    I can't fine a procedure to calibrate the 30-4900.   What am I missing?  I don't think 14.2 is correct based on the expected AFR in closed loop as well as the X-Series readings confirmation.  Thanks in advance for any assistance.

 

 

 

 

 

 

cmkelly01
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Last seen: 2 months 3 weeks ago
Joined: 11/09/2014 - 15:45
I have a 30-4900 that reads

I have a 30-4900 that reads low (~14.2) when in closed loop, as well. I looked through the forums some time ago, and found a number of people with the same problem that was never really resolved. Some returned the gauge for recal, but continued to have the same issue afterwards. AEM at one point said that the gauge may be a bit off at stoichiometric, but would be accurate at WOT, "where it counts". Or, at least that's my recollection. Mine seems to be correct at WOT, FWIW. I just live with it. Good luck!