Hey all, looking for some help and options to log boost with evoscan using a AEM boost gauge.

I'm looking to log boost using the factory ecu / evoscan using the output from the AEM 30-0306 boost gauge which comes with a 3.5 bar sensor. I haven't found any threads specifically about the 30-0306 gauge but in general from the research I've done it looks like others have wired up the signal output from the boost gauges to pin #73 or #92 depending on if its a 3 or 4 plug ECU.

My evo is a 04 JDM VIII MR - no map sensor on these models (as far as I'm aware) so unfortunately I can't just buy a 3 bar map sensor and connect it up to the plug on the IM like with other models.

I wanted to double check with anyone else that has done this if this is correct and also which wire would I be connecting to the ecu? The gauge is currently wired up and working fine.







Cheers

 

Just in case anyone is looking to do this, I ended up connecting the White 0-5V wire to pin 92 on the 8MR ECU and function (0.2488*x)-20.648 in EvoScan. If someone could explain why this function works and the one above in the mannual does not work that would be helpfull.

In EvoScan I used the below settings:
- Display: Boost GM-3Bar MAP
- Request: 38
- Function: (0.2488*x)-20.648

I am running ROM ID 96260709 Tephra V7 and did not make any adjustment to the MUT Table in EcuFlash. If you are new to this some things to note:

- the white 0-5v + wire cannot be connected to any free port on the ECU, it must be a ACD port (Analog to Digital), from what I have read on the 8MR ecu pin 92, 73,74 are all ACD.
- the brown 0-5v - wire must be connected to a ground point. If you notice in EvoScan the reading jumping around or innaccuarte it could be a bad ground connection.
- the function (0.2488*x)-20.648 worked for me and, you may need to tweak this.
- at idle the reading in EvoScan will not match the gauge - this is a known issue. The reading should match once under some load.

Cheers

 

i just finished rewiring my zeitronix into the ecu and it too had a similar discrepancy. The equation given by them was (volts)*2+9.6 but it ended up being (volts)*10+9.6 to line up. I'm not sure if that means the assumption 0 volts=0 and 5 volts=255 (0.0196*x) is wrong or what the deal is. It could just be analog signal error due to different ground potentials, but I wouldn't expect such a dramatic effect, and my zeitronix is grounded through the ECU grounds so it seems less likely.

 

double post

 

Tapping into the ECU ground sounds like the smarter and tidier way to do it, maybe that's why I had to a just my equation..?...I might do that when I get around to connecting the AFR gauge to the ecu.

 

It helps eliminate the chance that they are at different ground potentials which would screw with the volts the ecu sees coming out of the wideband.