AEM aem + jdm fd3s no go?
02-19-11, 05:27 AM
#1
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aem + jdm fd3s no go?
I have a jdm 1994 fd3s and I bought a Aem 30-1800 pnp ecu for the usdm fd3s.
I tought if the apexi pfc (jdm) can work on the usdm rx7, that means the pinout are the same but it seems to me they are not, why I say this? because last night I plug in the Aem for the first time and it does not read RPM that means does not read crank angle sensor.
everything else seems to work it was late mast night when i tried it, two things we notice:
1. no RPM
2. and the batt volt in the aem shows 10.8 or keep changing 10.2-10.5-10.6 but very fast.
When i checked with a voltmeter it's 11.87, still low but higher then what aem shows me.
so right now we are going to keep looking for solution, but if anyone has a jdm pinout and a usdm pinout please post.
or any info help appreciated.
thanks
I tought if the apexi pfc (jdm) can work on the usdm rx7, that means the pinout are the same but it seems to me they are not, why I say this? because last night I plug in the Aem for the first time and it does not read RPM that means does not read crank angle sensor.
everything else seems to work it was late mast night when i tried it, two things we notice:
1. no RPM
2. and the batt volt in the aem shows 10.8 or keep changing 10.2-10.5-10.6 but very fast.
When i checked with a voltmeter it's 11.87, still low but higher then what aem shows me.
so right now we are going to keep looking for solution, but if anyone has a jdm pinout and a usdm pinout please post.
or any info help appreciated.
thanks
02-19-11, 09:02 PM
#5
My 30-1800 EMS has never measured battery voltage correctly, the value displayed in the AEMPro software is always about 1.0V lower than the voltage you can measure at the 12V input pin on the ECU.
If you're measuring 11.9V at the battery that is pretty low, not a good starting point if you're trying to fire a car up for the first time on a new setup. A healthy battery should measure at least 12.6V when the engine is off, it might be a good idea to charge yours or replace it with a new one.
I put my EMS in a friend's RX-7 to try and help troubleshoot a possible wiring or ECU problem, and it didn't measure RPM when cranking even though his battery was healthy. The FD has 2-wire magnetic type sensors, which means the signal strength will depend on the engine speed and the air gap distance between the sensor and the trigger wheel. We used a very thin washer to decrease the air gap by moving the sensor closer to the trigger wheel, then the EMS worked with his car. My car always worked OK without any modifications or washers.
If you're measuring 11.9V at the battery that is pretty low, not a good starting point if you're trying to fire a car up for the first time on a new setup. A healthy battery should measure at least 12.6V when the engine is off, it might be a good idea to charge yours or replace it with a new one.
I put my EMS in a friend's RX-7 to try and help troubleshoot a possible wiring or ECU problem, and it didn't measure RPM when cranking even though his battery was healthy. The FD has 2-wire magnetic type sensors, which means the signal strength will depend on the engine speed and the air gap distance between the sensor and the trigger wheel. We used a very thin washer to decrease the air gap by moving the sensor closer to the trigger wheel, then the EMS worked with his car. My car always worked OK without any modifications or washers.
02-19-11, 10:15 PM
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The above is correct about the airgap although even the sensors themselves can be a little different one from the other. You can adjust the settings in the AEM and it will work better.
As to battery voltage the AEM "see" what the ECU's power harness gets. If you measure the voltage with a DVOM at the 12V source pins you will see what the AEM sees, even though the voltage at the battery might be higher.
Also, the AEM ECU will not typically fire the coils/injectors below 9Volts, so even though the engine cranks the voltage might drop pretty low during cranking ( I have noted 7V while crnaking at times) and the car will not start.
As to battery voltage the AEM "see" what the ECU's power harness gets. If you measure the voltage with a DVOM at the 12V source pins you will see what the AEM sees, even though the voltage at the battery might be higher.
Also, the AEM ECU will not typically fire the coils/injectors below 9Volts, so even though the engine cranks the voltage might drop pretty low during cranking ( I have noted 7V while crnaking at times) and the car will not start.
