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Old 08-28-2011, 07:19 PM   #1
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Default EMS-4 wiring help

after many hours of searching still stuck on some wiring. This is for a EMS-4 for a 2002 Engine in a kitcar - no stock wiring.

99 plus is Hall not Mag, correct ?
VVT wires to the VSS pin ?
MAP - wires to Manifold Pressure sensor, correct?
VCC is the 5 volt output ?

now the fun part

3 wire coolant temp. Blk/red (grnd?), purple/white (?), Red/blue (sensor?)or do I have to go to GM sensor?

3 wire crank sensor, Red, Blue, Black - are what?

Savington has been very helpful but don't want to call him everyday

thank you for all help.
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Old 08-29-2011, 01:25 PM   #2
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Originally Posted by twpipe View Post
99 plus is Hall not Mag, correct ?
All '90-'05 Miatas use hall-effect crank and cam sensors. Well, they're not literally hall-effect, but they are wired as though they were. (eg: open-collector, external pullup.) The only pure magnetic sensors were the crank sensors on '96-'97 cars, and they were used only for OBD-II misfire detection, the main sensors were still hall-style.

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VVT wires to the VSS pin ?
Not sure how AEM treats this (can they even do VVT control?) but I can't imagine why it would get anywhere near VSS. VVT needs to be connected to a pin which can directly drive a high-current solenoid.


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MAP - wires to Manifold Pressure sensor, correct?
VCC is the 5 volt output ?
Vcc typically describes the voltage supply to a device, not the output from it. So in the context of a MAP sensor, Vcc would be +5v from the ECU to the power input pin of the MAP sensor.


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3 wire coolant temp. Blk/red (grnd?), purple/white (?), Red/blue (sensor?)or do I have to go to GM sensor?
The CLT sensors on the '99+ cars are actually two sensors in one.

Red / blue and black / red are the CLT signal for the ECU, where black / red is ground in the stock configuration.

Purple / white is the CLT signal for the temperature gauge in the dashboard. This one goes to ground through the body of the sensor.


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3 wire crank sensor, Red, Blue, Black - are what?
Hmm. This doesn't match the documentation I have for any '01+ engine. The crank sensor should be white/red (+12), black/blue (gnd), and violet/white (signal).

Could you post a picture, and also let us know the specific year of the engine? There were some wiring differences between '01-'02 and '03+. Also, is this a US-spec car, a Euro car, etc?
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Old 08-29-2011, 01:51 PM   #3
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I'll confirm with AEM on VVT and MAG sensor wiring, VCC is from the ECU so you are correct that it is 5V output. The wires from the crank sensor are Red, Blue, Black but switch to what you stated at the connector on this 2002 engine.
Greatly appreciate the help, a few more wires and then program set up to fire off.
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Old 08-29-2011, 02:18 PM   #4
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VCC is from the ECU so you are correct that it is 5V output.
Ok, those were two seperate questions.

Yeah, the +5 supply out of the AEM should go to a couple of different places. The MAP sensor is one. The TPS also needs +5 to operate. In the factory wiring harness, pin 4L (a light green / red wire) is the "Vref" pin, which carries +5 to the TPS, the EGR sensor, the FTP sensor, and the transmission control module (for automatic cars).


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The wires from the crank sensor are Red, Blue, Black but switch to what you stated at the connector on this 2002 engine.
Oh, yeah. I forgot that the crank sensor has a pigtail on it- I was thinking that the engine harness plugged directly into it like the cam sensor. The pigtail wiring isn't shown in the service manual. It's been a while since I laid hands on an NB engine.


That's a hell of a fun-looking project, incidentally.
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Old 08-29-2011, 04:18 PM   #5
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Joe
It's been a fun "project" but so very anxious to get in back on the road, i'ts taken 8 times as long as I had planned. Delays in getting parts then a lot of Life happening . Fortunately in CA. we have many months of good weather ahead. Hope to fire it off this week.
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Old 08-30-2011, 09:32 PM   #6
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Not sure how AEM treats this (can they even do VVT control?) but I can't imagine why it would get anywhere near VSS. VVT needs to be connected to a pin which can directly drive a high-current solenoid.
All of the AEMs can do VVT. On the EMS-4 it gets run through one of the GPIOs - the second batch of 4 is configured to run a PWM solenoid.

Quote:
Hmm. This doesn't match the documentation I have for any '01+ engine. The crank sensor should be white/red (+12), black/blue (gnd), and violet/white (signal).
The colors change at the connector. I am 99% sure that the red wire is the +12v. The middle wire is the signal. The one that's left is the ground.
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