AEM X Series AFR not matching Megasquirt - CANBUS
#1
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Hi guys. I used to have an Innovate MTX-L wired to my Megasquirt using the analog signal. I just now swapped out the Innovate for an AEM X Series UEGO and I'm now using the CANBUS protocol to read the AFRs. Everything functions as it should, but I noticed that the AEM is approximately 0.5 leaner than what is showing in Tunerstudio. I'm not sure if maybe my CANBUS settings might have something to do with it? Anything I can play around with to try and get this closer to even? I've attached my tune to help with troubleshooting.
I used the following threads to help me with my CANBUS settings:
https://www.miataturbo.net/megasquir...9/#post1470957
https://www.miataturbo.net/megasquir...not-ms3-98941/
I used the following threads to help me with my CANBUS settings:
https://www.miataturbo.net/megasquir...9/#post1470957
https://www.miataturbo.net/megasquir...not-ms3-98941/
Last edited by Orinawak; 06-03-2023 at 10:32 PM.
#2
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So I went back and checked my wiring, everything looks to be fine. I also have the gauge end of the CANL and CANH wires terminated with a 120 ohm resistor across them.
I do not, however, have the analog signal wires hooked up. Do I need these hooked up if I’m using CAN? This thread suggests that I should?
https://www.miataturbo.net/megasquir...ctions-106404/
I do not, however, have the analog signal wires hooked up. Do I need these hooked up if I’m using CAN? This thread suggests that I should?
https://www.miataturbo.net/megasquir...ctions-106404/
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Well I sent AEM support an email to see what they say since I am having a really hard time finding any info on this. I just tested again yesterday and when Tunerstudio shows 14.8 AFR, my AEM gauge shows 15.3 using CANBUS. No idea what is going on.
#7
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![](https://cimg3.ibsrv.net/gimg/www.miataturbo.net-vbulletin/1204x774/can_settings_1_c8d91f38cbf28a456b3d0a0cd0ff26354d465dc3.png)
![](https://cimg4.ibsrv.net/gimg/www.miataturbo.net-vbulletin/933x909/can_settings_2_4b4d1b4f6fcc6f2462ab6c91e84145c5b25bf6f3.png)
![](https://cimg5.ibsrv.net/gimg/www.miataturbo.net-vbulletin/478x676/can_settings_3_ecfa897345d7da81ca3ea23dbab72bfbddf628e2.png)
![](https://cimg6.ibsrv.net/gimg/www.miataturbo.net-vbulletin/619x856/can_settings_4_b1d1ce2fca717eaf0adcf5883eb3f3f42c9d4fe4.png)
![](https://cimg7.ibsrv.net/gimg/www.miataturbo.net-vbulletin/1494x885/can_settings_5_6521cf2f1dfa71114ae2b75d5f8a0f5dc0017bd5.png)
![](https://cimg8.ibsrv.net/gimg/www.miataturbo.net-vbulletin/478x723/can_settings_6_68bebb4c7d0685b636f5621cdb3f095c2a172960.png)
![](https://cimg0.ibsrv.net/gimg/www.miataturbo.net-vbulletin/531x658/can_settings_7_37d029eb05849a890e4694fd3ca89afb8cf04be6.png)
#8
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In case anyone comes across this issue in the future, I figured it out. For some reason, my Stoich AFR was set to 14.1. As soon as I changed it to 14.7, the reading is spot on. I have absolutely no idea why mine was set like that, but all is good now.
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When I tried to go back to CAN with my AEM (since I'm back to 1.5.2 FW), I cannot get it to work. If I set it as "Innovate", it works, but is not correct values. If I put it to AEM X Uego, I get "0" AFR.
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