AEM High Output Inductive Coils

[polarmoment]

The problem with bike coil sticks is that some are inductive, some are CDI. The ones I have are inductive, but people try to use the CDI sticks for inductive and they misfire and burn up fast, since they're not designed to store a charge, only step up the voltage dumped through them by the capacitor.

But yes, either way you'd need some form of driver circuit. The 350Z coils have built in igniters. Most OEM coils do nowadays. The 350z, honda and toyota coils can all be driven with a logic signal from the ECU. All those I listed use falling edge trigger.

 

[Moonlight GSX]

Here's the "finished" product, the only thing I have a question about is the dashed line (Switched +12V Constant)... where is this constant actually coming from? I know it's from the battery but where from the battery? Is it being split (i.e. PTU pin 6 and connection at coil packs) between the two?

Other than that it seems like it makes sense - this should also allow me to run sequential ignition and control dwell time.

Edit:
I may have to re-do the coil 3 and 4 ECU connections... they may be in the wrong spot.

 

[godschylde777]

Good read. I learned a bit. I am useing the cop set up with a dis 2 msd. So if I understand, I am gaining nothing over stock?

 

[Moonlight GSX]

Good read. I learned a bit. I am useing the cop set up with a dis 2 msd. So if I understand, I am gaining nothing over stock?

From what Polar said, yes. The only thing I think you would run a problem into is that from what he said...

COP coils have very low inductance. The proper way to drive COP coils is to ramp dwell based on engine load. Short dwell for low load conditions, then ramp the dwell up for higher boost. This keeps them from overheating under normal operating conditions. There are only a handful of engine management systems that can do this, unfortunately.

Alright so I wonder if this seems logical:

Pins 1 and 8 leave the PTU and go to the coil pack triangular connector, with that being said, would I be able to (as shown in the above diagram) "reroute" the connector by connecting the original connector for the coil packs to that one and then wiring the two wires from that connector back to the ECU at pins C52/C62 (coil driver 3/4)? If my theory is correct I should be able to add the two pins without having to cut the stock engine harness, not to mention there "should" be a very small voltage drop as it may just be a through wire between pins 1 and 8 to the two pins (excluding the +12V) on the stock coil pack connector. Basically rather than the signal leaving it'd be going through the stock coil pack connection and going back to the "modded wiring harness" (PTU) and giving coil triggers to 3 and 4.

 

[Moonlight GSX]

So I figured rather than try and re-route the triangular connector back to the ECU I can just just wire everything up through one connector (but not the PTU). This is what I've found...

Connector 1
Connector 2

Figured I'd remove the old connector and replace it with one of these or something similar...

 

[Moonlight GSX]

So I've got all the equipment and things needed to create this harness but my current problem is I don't know where to mount these? With that being said I can't determine how to position each of the connections to best fit the positions of the coils themselves... any ideas?

 

[dexterholland04]

Thanks for the intelligent tech posts, gentlemen! We don't often get this kind of information anymore. Good read.

 

[Moonlight GSX]

Thanks Dex.

So I want to tie the other 3 sensors' 4 other signals (Gnd, Sensor Gnd, Cyl Head Gnd, +12V) to the 1st as my convoluted cable wrap is too thin and I'm keeping the amount of pins on the ignition harness to engine harness down to a mere 9 pins (rather than 20). With that being said what is the amount of current running from the +12V, and the Sensor Gnd at the ECU? I'm sure that's the only problem I need to worry about is the current limiting factor yes?

Edit:

I may have solved my own question... if the peak secondary current is 102mA +/- 10% at a 71:1 winding ratio (primary:secondary) then the most I should see is 7.8A at each coil? Meaning I'm going to run into a current limiting factor of about 31.2A total... 16 gauge wire can't handle but about 20A or so before it runs into voltage drops (excessive). Correct me if I'm wrong... I'm hoping I'm looking into this correctly.

 

[TrevorS]

I wouldn't recommend connecting the transistor pack tach output signal to ground, it's an active output, not an input. Also, the OE power transistor pack doesn't contain current limiters. The limit seen in use is due to a combination of coil primary resistance (.8 ohm), transistor C-E impedance (depends on the current), and ground lift plus voltage supply drop due to the current. With a non-sagging power supply and solid ground, the transistors are at least capable of delivering 9A, most likely more -- 'course, as the current goes up, the more heat that will need to be dissipated.

Curious as to where the 4.8mH spec came from for the AEM IGBP primary (don't see it in the spec sheet), if it's true, it will need more charge time than OE (bench measured at 3.9mH) to achieve full spark energy.

 

[Moonlight GSX]

I wouldn't recommend connecting the transistor pack tach output signal to ground, it's an active output, not an input. Also, the OE power transistor pack doesn't contain current limiters. The limit seen in use is due to a combination of coil primary resistance (.8 ohm), transistor C-E impedance (depends on the current), and ground lift plus voltage supply drop due to the current. With a non-sagging power supply and solid ground, the transistors are at least capable of delivering 9A, most likely more -- 'course, as the current goes up, the more heat that will need to be dissipated.

Curious as to where the 4.8mH spec came from for the AEM IGBP primary (don't see it in the spec sheet), if it's true, it will need more charge time than OE (bench measured at 3.9mH) to achieve full spark energy.

Well the reason the tach signal is connected to ground, sensor ground, is because my tach signal will be lost in the changing of my setup. I have removed the PTU all together as each coil has its own "PTU" imbedded within it. The only other way I can do this is what was previously stated by Beau - using the CPS (in my case the 1G black top CAS signal) to generate a tach signal for me.

Just to clarify though, you are talking about the stock transistor yes? Or are you talking about the ones located within each coil?

 

[TrevorS]

I'm referring to the OE J722T transistor pack. Regarding the tach output signal, as I said, it's active and should never be tied to ground regardless of conditions -- just leave it disconnected. On the other hand, as you show, if the tach output is not needed, it's still best to provide ignition power to the transistor packs, it protects the packs from internal leakage or even breakdown. Leaving the power disconnected could potentially lead to early failure.

 

[Moonlight GSX]

I'm referring to the OE J722T transistor pack. Regarding the tach output signal, as I said, it's active and should never be tied to ground regardless of conditions -- just leave it disconnected.

Leaving it disconnected wouldn't be a problem but I'm still curious as how the stock transistor and the ECU are tied together at C58 (tacho pin). The wiring diagram says they are tied together and this thread in post #3 says that pin 4 is the output signal for the tach. Although here it says that the tach is an output (as you have said)... so which way is it actually going? Will there still be a tach signal coming from the 1G CAS I plan to run (simulated CPS and CAS signal)? Just curious kinda want to keep the tach in operation (daily driver use)...

 

[TrevorS]

The tach signal is sourced from the coil pack on the '90 and from the transistor pack for '91 thru '99. In both cases, it's generated by performing a logical "OR" on the power transistor collector outputs.

 

[Moonlight GSX]

The tach signal is sourced from the coil pack on the '90 and from the transistor pack for '91 thru '99. In both cases, it's generated by performing a logical "OR" on the power transistor collector outputs.

Ah so exactly how is it sourced on the coil pack on the '90 model as this may be the basis for what I need to do to mine to get it to work properly. Although I'm thinking I can still tap off the CAS sensor and use that signal for the tacho input (to ECU).

 

[TrevorS]

Ah so exactly how is it sourced on the coil pack on the '90 model as this may be the basis for what I need to do to mine to get it to work properly. Although I'm thinking I can still tap off the CAS sensor and use that signal for the tacho input (to ECU).

Contact Mitsubishi to get the details of the circuitry, otherwise, accept the professed function of the CAS (no personal experience). Myself, I'm limited to reading the circuit diagrams and observing physical behavior, I've no reason to distrust either.

FWIW -- the '90 requires the coil "tach" signal to pass through a noise filter before delivery to the ECU and dash display. This is unlike the '91-'99 transistor pack signal. Do what makes best sense to you, but recognize that if you don't appreciate electronic behavior, then you cannot be expected to arrive independently at the correct solution. You've been provided with good input, I suggest using it.

 

[Moonlight GSX]

I have been just making sure and confirming it's correct. "Measure twice, cut once." I'm also on a "trust but verify" basis as well, trust me I take what everyone has said (in this thread and others) with careful consideration.

 

[Moonlight GSX]

Quick question, how much current goes to the sensor ground at pin 92 on the ECU? Trying to determine the wire gauge for that signal, but unlike the +12V signal and battery return it shouldn't be high current (as their diagram states). Am I correct on this?

 

[Moonlight GSX]

So I'll be using a 1G Blacktop CAS, I should be able to tap off the wire that would normally go to the CPS? Or would it be best just to tap the wire from the CAS (wire that goes to the CAS connector)?