Resolved 1G Standalone Link G4+ ECU, Tach signal with COP kit.

[Anfurnyy]

Car is a 93 (so 91+ ignition setup) I'm looking to move to a direct fire / sequential ignition setup using the Brewed Motorsports kit with their wiring harness. I am on a standalone Link G4+ ECU and will use ignition outputs 1-4 for direct fire.

My question is if the PTU is deleted, how does the car get tach signal to the dash and ECU? Is there another place to tap into? Perhaps one of the ignition outputs from the ECU?

 

[motomattx]

If those coils are like the Toyota coils, they will have a tach output on them, that may not be able to drive the stock tach though, because our ignition transistor takes both channels and combines them and feeds them to the tach from my understanding, why are you bent on removing the factory transistor? is there a reason that you cannot leave it in play and use it to drive the tach with? it can be tucked like mine is. Also I am not sure that the G4+ can do sequential ignition on the plug and play version, if thats what you are using, the ECU uses one of the ignition channels for something else already.

 

[Anfurnyy]

If those coils are like the Toyota coils, they will have a tach output on them, that may not be able to drive the stock tach though, because our ignition transistor takes both channels and combines them and feeds them to the tach from my understanding, why are you bent on removing the factory transistor? is there a reason that you cannot leave it in play and use it to drive the tach with? it can be tucked like mine is. Also I am not sure that the G4+ can do sequential ignition on the plug and play version, if thats what you are using, the ECU uses one of the ignition channels for something else already.

I just checked and these GTR coils only have power, ground, signal pins.

I'm not really bent on it but its starting to sound like I'll need to keep it to keep the tach signal. It just would have been nice to get rid of it. How would one keep the PTU and go to a coil setup?

I checked with Link about the outputs and they verified that they can be changed. IGN 3 is used for the OEM fuel pump relay, and IGN 4 is used for the OEM fuel pressure solenoid.

 

[motomattx]

I just checked and these GTR coils only have power, ground, signal pins.

I'm not really bent on it but its starting to sound like I'll need to keep it to keep the tach signal. It just would have been nice to get rid of it. How would one keep the PTU and go to a coil setup?

I checked with Link about the outputs and they verified that they can be changed. IGN 3 is used for the OEM fuel pump relay, and IGN 4 is used for the OEM fuel pressure solenoid.

I saw your post on the Link forums. I must have been told that because they thought that I had the Evo 1,2,3 ECU, but I do remember them telling me that since that was also my plan.

As far as keeping the transistor I would try connecting a trigger wire from the number one and the number two coils to the coil one and coil two inputs on the transistor and leave the rest of the transistor hooked up as it is, this is in addition to still having the trigger wires going to coils one and two still, just splice a second wire into the trigger wires for them, I would imagine that would work, its worth a try.

 

[Anfurnyy]

I saw your post on the Link forums. I must have been told that because they thought that I had the Evo 1,2,3 ECU, but I do remember them telling me that since that was also my plan.

As far as keeping the transistor I would try connecting a trigger wire from the number one and the number two coils to the coil one and coil two inputs on the transistor and leave the rest of the transistor hooked up as it is, this is in addition to still having the trigger wires going to coils one and two still, just splice a second wire into the trigger wires for them, I would imagine that would work, its worth a try.

Thanks, I'll definitely look into that for sure. Have you got any pictures of how yours is tucked? Mines sitting on a JMFab coil bracket right now.

 

[jdxnc]

I don't know about LinkG4 but with the Fueltech it gets the rpm signal from the crank sensor and can output to the oem cluster.

 

[Anfurnyy]

I don't know about LinkG4 but with the Fueltech it gets the rpm signal from the crank sensor and can output to the oem cluster.

That was the other thing I thought about trying was tapping into the black wire on the CAS and using that as the tach to the cluster.

I feel like a ton of people have moved to a sequential/ direct fire setup and removed the PTU but no one answers how to keep the tach signal.

 

[jdxnc]

That was the other thing I thought about trying was tapping into the black wire on the CAS and using that as the tach to the cluster.

I feel like a ton of people have moved to a sequential/ direct fire setup and removed the PTU but no one answers how to keep the tach signal.

Does the G4 not have a tach output?

 

[Anfurnyy]

Does the G4 not have a tach output?

I actually don't think it does. Or not in the pin out / pin functions in the Link software.

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[jdxnc]

I actually don't think it does. Or not in the pin out / pin functions in the Link software.

Tach signal

Hello, I have link g4+ obd1 92-95 honda, AEM eps, coil on plugs on 90 ef civic hatch. My blue tach wire off my harness, were do i connect it to on the ecu to get my tach to work.

forums.linkecu.com

From my quick research, you can assign tach output to any AUX output.

 

[Anfurnyy]

Tach signal

Hello, I have link g4+ obd1 92-95 honda, AEM eps, coil on plugs on 90 ef civic hatch. My blue tach wire off my harness, were do i connect it to on the ecu to get my tach to work.

forums.linkecu.com

From my quick research, you can assign tach output to any AUX output.

Yeah I was just about to reply and say that. Was just looking at the help file.

If I can avoid using another output I will. But if not I might have to do that.

 

[steve]

I used the CAS TDC signal when I had an SAFC for it's RPM input but I didn't like connecting to a key primary signal with some non-critical device that could malfunction and disable the car.

Keep in mind that both CAS signals are from the factory +5v Open Collector outputs. The ECU provides the bias voltage.

 

[Anfurnyy]

I used the CAS TDC signal when I had an SAFC for it's RPM input but I didn't like connecting to a key primary signal with some non-critical device that could malfunction and disable the car.

That's true. I didn't even think about it malfunctioning.

 

[Anfurnyy]

I think I'll probably just go with using an output to drive the tach. Seems like the cleanest and easiest way to get the tach done. I'll report back when I get it installed and hopefully working so people know.

 

[Anfurnyy]

Ended up using Aux 2 ( EGR solenoid output) for Tach output to the factory dash. I just cut both wires right at the ECU and joined them and it seems to be working fine.

 

[marcturbide]

hey there anfurnyy wondering how it worked out the tach ouput? im installing my g4x in my early evo and running into same issue as you did

 

[Anfurnyy]

hey there anfurnyy wondering how it worked out the tach ouput? im installing my g4x in my early evo and running into same issue as you did

I ended up just using an output from the ECU to the tach wire.
The engine gets RPM from the CAS sensor if i remember right so as long as the ECU is seeing RPM signal, you can just set an output to any unused pin and connect it to the wire that runs to the tach and that should do it.
At least thats what i did and its still working fine.

 

[marcturbide]

can you share your tach output setup just for me to have an idea there's a bunch of option been told by a link moderator on g4x forum that might need higher voltage to make it work

 

[Anfurnyy]

can you share your tach output setup just for me to have an idea there's a bunch of option been told by a link moderator on g4x forum that might need higher voltage to make it work

I can upload a picture of something tomorrow.
The Evo ECU might be different though

 

[Anfurnyy]

can you share your tach output setup just for me to have an idea there's a bunch of option been told by a link moderator on g4x forum that might need higher voltage to make it work

This is my entire tach setup. Aux 2 OUTPUT set as tach, with my tacho settings. This is all im using

Your pinout is probably different than mine so you need to find an unused output and then set that as tach cross reference which pin that is on the ecu and wire it to the tachometer wire

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