AEM is reading different than the datalog

tristanlee85 · Post by **tristanlee85** » Mon Jul 17, 2006 8:06 pm

When I am at idle or driving decently slow, the AFR on the AEM is reading the same as the gauge displayed in MegaTune. I'm trying to read the the AFR in the datalog so I can see where I need to add fuel since when I'm at WOT @10psi, the AEM gauge is showing I'm in the 13's and 14's. That's not acceptable. When I look on the datalogs, what seems to read out 14:1 reads out roughly 12:1, so I'm just at a guess as to what I need to believe. I have my setting on AEM_LINEAR which seems to be the one accurate at idle and such. I'f I choose the AEM_NON_LINEAR, I'm reading 14's AFR while the engine is off...

Is there something I need to change somewhere so I'm not guessing here?

DrBrown · Post by **DrBrown** » Wed Jul 19, 2006 12:07 pm

Im just throwing this out there, but Ive heard several people say you have to calibrate AEM gauges. I never did it to mine personally because their wideband tech support is about as intelligent as a dead fly. So I never calibrated my gauge but I've noticed theres a tiny difference between the gauge and the log readings Ive got. So you arent alone. But if mine were off that far Id be scared.

tristanlee85 · Post by **tristanlee85** » Wed Jul 19, 2006 2:36 pm

Well, I've got no way to calibrate it as far as I know. I was thinking it might be the voltage tables or equation built into MegaTune that giving it an incorrect reading.

DrBrown · Post by **DrBrown** » Wed Jul 19, 2006 2:49 pm

You did tap the white wire in the main AEM harness that comes from the sensor right? Just wanted to make sure because there are many wires on that harness, some provide different signals. Mines pretty close and its the white wire.