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MSD 6al with 8910 or 8920 install


MontyTSI
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I finally bought an 8920 and installed it to test the install and perfect the diagram. Here are diagrams for both 8910 and 8920. If your still using the stock ecu this is the only way to install the 8910 if your keeping the igniter/knock box and the 8920 if you are getting rid of it (not recommended for most)!

 

Keep in mind when using the 8920 you get rid of the stock igniter and knock control. And you have to cut and splice the harness from the distributer (unless you do like i did and cut the engine harnass part off of a parts car ;) )

 

http://www.26liter.us/gallery/albums/userpics/10123/msd_install_with_8910.jpg

 

http://www.26liter.us/gallery/albums/userpics/10123/msd_install_with_8920.jpg

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  • 1 year later...
I'm just curious, I assume the tach won't work but are we able to install the msd without the tach adapter?

 

The ECU runs off the tach signal as well so the answer is no.

I tried it a couple weeks ago and you do need the tach adapter or it will not run.

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The tach won't work without the adaptor and neither will the ECU. It's not that the tach itself is needed (the ECU doesn't know/care if the tach works or is even installed)... the ECU needs the same signal that feeds the tachometer for a couple things:

1: the ECU uses the pulses from the ignition system to measure idle RPMs; it then tweaks the ISC as needed to get the correct idle RPMs. The tach of course just displays this pulse rate.

 

2: the ECU holds the ECI relay ON (=fuel pump power) only when it sees these ignition pulses. If it can't see them, it assumes the car was just in an accident and it kills power to the pump and fuel system for safety. So without the tach adaptor, the ECU won't keep the fuel pump running. In theory, if you hold the ignition key in START for long enough (more than 15 or 30 seconds, something like that) it "gives up" looking for that signal and turns the ECI relay ON; at the same time it sets the "ignition pulse" error code. This is a pretty flakey way to get a StarQuest running with the MSD though - relying on this "give up" function. The tach adaptor conditions the MSD signal to something the ECU and tachometer both understand.

 

mike c.

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