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Alpha for president
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Discussion Starter #1
I know that this question has been asked and answered but no search so no find...I want to wire my FJO into the AEM but i dont know what to look for.I'm pretty sure it's 1 wire from the FJO but i'm not sure...any help would be great...thanks
 

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I need some info as well. I wired my fjo analog output wire into 47b of the ecu harness of the aem and went through the o2 wizard and set it up for fjo, but my aem reads 5.7 afr and my fjo display says 20.0
 

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If it's the first model FJO, there is a four wire plug that has the main power and ground. On that plug there will be a grey wire and that's the analog output you need to wire into the O2 input on the AEM.

On the newer version FJO, that wire will be red.

I've got no idea about your problem though Eddie, sorry.
 

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I got it figured out, the new version of aempro defaults to meth as the fuel type, runs11 pm me you email and I will send you a doc file for installing the fjo, if you already have it installed there should be a four pin connector on the fjo box, one white 12v, one black ground, above the black ground wire there is an empty spot on the connector if you look close you will see it is labled with 'A' this is the analog out of the fjo and can be wired into terminal 47b of the aem and it should appear as o2#1.
 

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runs11, my pics did not turn out that well but here is a pic from the fjo manual. You are looking for to run a wire from the "a" port of this 4 prong connector, this should be the empty spot above the ground wire for the fjo box.

 

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Hey Eddie,
How do you change the fuel type on the AEM. I'm having the same trouble you had.

Thanks,
Daniel
 

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Alpha for president
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Discussion Starter #7 (Edited)
If it's the first model FJO, there is a four wire plug that has the main power and ground. On that plug there will be a grey wire and that's the analog output you need to wire into the O2 input on the AEM.

On the newer version FJO, that wire will be red.

I've got no idea about your problem though Eddie, sorry.
ok...i have the older FJO...the 4 plug that you'retalking about, is it the square or the flat one, i was on the FJO site and i'm guessing from what i can see it's the square one...but not sure...thanks
 

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ok...i have the older FJO...the 4 plug that you'retalking about, is it the square or the flat one, i was on the FJO site and i'm guessing from what i can see it's the square one...but not sure...thanks
The flat one is for the display. The square one has the output you need. That plug has a main power and ground to power the controller and also has the 0-5 volt output and sensor ground. Use one of the ecu ground pins (don't have the pinout infront of me) for that sensor ground.
 

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would not converting them to gas be an explanation for why the aem readout and the FJO gauge are different? Would you guys trust the gauge or the readout when connected to the ecu?
 

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would not converting them to gas be an explanation for why the aem readout and the FJO gauge are different? Would you guys trust the gauge or the readout when connected to the ecu?
I would trust the fjo gauge over the aem, there have been some instances that I found when researching the fjo to aem connection where the aem would read about .1vdc off on some cars. This may not be much but the fjo legacy curve is not a linear curve. Some poeple have grounded the fjo to the ecu ground to fix this, others have lived with it, and some never see it. Me on the other hand just sent my aem back because the aem was reading 3 points lower than my fjo gauge with the gain adjustment maxed out.
 

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I would trust the fjo gauge over the aem, there have been some instances that I found when researching the fjo to aem connection where the aem would read about .1vdc off on some cars. This may not be much but the fjo legacy curve is not a linear curve. Some poeple have grounded the fjo to the ecu ground to fix this, others have lived with it, and some never see it. Me on the other hand just sent my aem back because the aem was reading 3 points lower than my fjo gauge with the gain adjustment maxed out.
Oh wow. Thats wild, i would never have guessed that was an issue!

Thanks for the info, good stuff!
 

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I would trust the fjo gauge over the aem, there have been some instances that I found when researching the fjo to aem connection where the aem would read about .1vdc off on some cars. This may not be much but the fjo legacy curve is not a linear curve. Some poeple have grounded the fjo to the ecu ground to fix this, others have lived with it, and some never see it. Me on the other hand just sent my aem back because the aem was reading 3 points lower than my fjo gauge with the gain adjustment maxed out.

That is some crazy shit!
 

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What is so wild about it? The AEM reads a voltage and you have to tell it what AFR to spit out for that voltage. Having to send the whole unit back because you can't adjust for it is nuts. I hope that isn't a common problem.

Daniel
 

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The problem is the voltage differential between the AEM EMS power source and where you wired in the FJO. I recommend using the same ground and +B to power the AEM EMS and the FJO. On my car that was easy - ground to the intake manifold (same bolt as factory harness) and power source was from the old fuel pump resistor connector, which conveniently ended up with the same wire length from the battery to the FJO as from the battery to the AEM EMS. I had already run a new circuit for my fuel pumps and did not intend on running the stock O2 sensor at all so neither the fp's or O2 heater were on the +B circuit. I have the v2 FJO and set it for a 0-5V linear curve and set up the AEM EMS for the same. My gain is 1.00.

Also, the FJO LED display is SLOW. I wouldn't trust it.
 

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What is so wild about it? The AEM reads a voltage and you have to tell it what AFR to spit out for that voltage. Having to send the whole unit back because you can't adjust for it is nuts. I hope that isn't a common problem.

Daniel

My aem was bad from the get go. The fjo was sending out say 5 volts and the aem would read 1.5 volts less, and this was with the gain maxed out. My aem arrived today from aem for repairs and with a gain of 1.38 on the legacy curve it is dead on.
 
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