Ever fitted an Msd or other brand ignition box with the stock ecu setup?

[humanz 3]

Hey everyone. Has anyone in group successfully fitted an Msd or another brand ignition box to the stock setup with the tachy relay, ignition amp, ecu and coil? 

 

I'm trying to fit one but not entirely sure why I'm getting no spark. System works as expected when the msd is not connected. This is on a 1.9 gti. 

 

Cheers. 

[petert 589]

Yes, I’ve done a few cdi units, including MSD. Which model?

 

I think I know what your issue is. I've actually only fitted them to race 8V's or 16V road/race cars, which don't use a tachymetric relay. They just use a normal relay to turn on the fuel pump.

 

You can only have two wires connected to the coil from the MSD. Orange and black? The tachymetric relay would normally be connected to the negative side of the coil and the same wire also triggers the tacho. Thus the tachymetric relay will never turn on. Likewise, your tacho won't work either.

 

Depending on which model, there are work arounds.

Edited June 26, 2022 by petert

[humanz 3]

So glad to hear that you've got some experience with this. Sounds exactly like what's happening. It's an Msd 6al, pn 6425. You're absolutely right: only two wires to the coil. I purchased an Msd tach adapter hoping it would fix the problemn(msd 8910 eis), but it still doesn't work. I'm not getting any spark. 

[petert 589]

Did you connect it like this? You don't actually need an 8910. You can use coil of a relay, pins 85-86 and disable the mechanical part so it doesn't make a noise. The tachymetric relay should connect on the tacho/8910 side of the diode.

 

You don't actually need an 8910. It's a big ugly beast. You can use coil of a relay, pins 85-86 and disable the mechanical part so it doesn't make a noise.

Edited June 27, 2022 by petert

[humanz 3]

I don't think my setup is like that. This is the setup currently I believe. So the setup in your diagram is the one to use? I don't understand when you say the coil of a relay. Are you saying that I can use a 4 pin relay with pins 85 and 86 instead of the tachy relay or in conjunction with the tachy relay? Also, is the tachy already connected to the wire from the ignition amp, or do I now need to splice the two wires together? 

I need to do a quick refresher on the connections for the tachy relay.... 

[petert 589]

Ah, sorry, I didn't pickup on the 8910-EIS. I was thinking older 8910.

 

I see in that diagram that you're using the magnetic pickup input? I would be using the "white" wire input, for your application.

 

I'm suggesting to use a $5 relay instead of your 8910-EIS. Open the case and disable the contacts. You could possibly still use the 8910-EIS. Don't use violet/green wire.

 

Do it one step at a time however. ie

1. connect the white wire to the ignition module.

2. hot wire the tachymetric relay, so the fuel pump is permanently on

 

This should make the MSD fire the coil and start the engine. If this works, go the next step to make the tachymetric relay and tacho work.

 

 

[humanz 3]

Finally got a chance to try your recommended setup. It worked. Used an y old relay and the white wire rather than the magnetic pickup ones. Car fired up almost right away. It's running with the tachy relay and the tacho works. 

 

Tried it with the 8910 eis. That didn't work. It would sound like it was about to start once I stopped cranking. Also, there was a puff or two of smoke from the engine bay, so I quickly gave up on that. 

 

One last question. Is the diode required for proper operation? If I asked that question before, forgive me. It's been a long week. 

 

Cheers. 

[petert 589]

Excellent. How good is the relay mod! It eliminates the need to pull the tacho apart. I would add the diode. I assume it filters out the 400V pulses being generated by the relay coil. The white wire is looking to be grounded by the ignition module and thus fire the MSD. A 1N4004 should suffice.

[humanz 3]

Thanks for the quick responses and insights. You don't know how much you've helped. Had this msd for over a year and couldn't get it figured out. Thanks a lot. Will see if I can get the diode, as my 8910eis never came with one.