bosch to megasquirt tach input

TimS · 04-03-2021, 01:37 PM

I'm trying to put a MS2 on a 1984 240 kjet turbo, IC, but don't want to get into ignition control( right now). Can I just go right from the coil or do i tap into the trigger wires from the dist.?
If I use the wires from the dist. do I just tap into each wire and back to the computer
at VR1 and Vr2, with it still connected to the bosch black box?

Tim

bobxyz · 04-03-2021, 01:52 PM

Normally, for fuel-only, you tap off the coil negative "-" tab. You need to build the MS2 Coil Negative circuits.

I don't know how Bosch Breakerless connects the 2 VR signals from the distributor. If it grounds one of the signals, you might be able to tap off the other VR wire to MS. (MS expects one of the 2 VR wires to be grounded.)

TimS · 04-03-2021, 07:34 PM

it is actually a microsquirt, so its ready for both. The manual says the same thing about the - side of the coil, but i mentions not to do if its a CDI unit. I'm not sure if that's the same as what a Bosch system is. I was hoping someone would say that they've run MS like that.

bobxyz · 04-04-2021, 10:25 PM

MicroSquirt is easy - connect the Opto +/- wires to the 2 tabs on the coil -/+ (they cross Opto+ to - tab).

CDI is the same thing as an add-on MSD red high-voltage multi-spark ignition box, not the factory Bosch Breakerless ignition.

Once you want to go beyond Fuel Only, you'll need a LH2.2 distributor, or will need to modify the Turbo K-Jet distributor to lock down the vacuum and centrifugal advance mechanisms.

Dirty Rick · 04-04-2021, 11:42 PM

I think You can also trigger the MS off the tach output of the power stage.?

04-03-2021, 01:37 PM	#1
TimS Board Member Join Date: Dec 2017	bosch to megasquirt tach input I'm trying to put a MS2 on a 1984 240 kjet turbo, IC, but don't want to get into ignition control( right now). Can I just go right from the coil or do i tap into the trigger wires from the dist.? If I use the wires from the dist. do I just tap into each wire and back to the computer at VR1 and Vr2, with it still connected to the bosch black box? Tim

04-03-2021, 01:52 PM	#2
bobxyz Board Member Join Date: Aug 2014 Location: Boulder CO	Normally, for fuel-only, you tap off the coil negative "-" tab. You need to build the MS2 Coil Negative circuits. I don't know how Bosch Breakerless connects the 2 VR signals from the distributor. If it grounds one of the signals, you might be able to tap off the other VR wire to MS. (MS expects one of the 2 VR wires to be grounded.) __________________ '85 245glt b21ft aw71 k-jet -> lh2.4

04-04-2021, 11:42 PM	#5
Dirty Rick Board Member Join Date: Apr 2013 Location: Cornholio, OR	I think You can also trigger the MS off the tach output of the power stage.? __________________ I don't know who I am when I am somebody else.

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04-03-2021, 07:34 PM	#3
TimS Board Member Join Date: Dec 2017	it is actually a microsquirt, so its ready for both. The manual says the same thing about the - side of the coil, but i mentions not to do if its a CDI unit. I'm not sure if that's the same as what a Bosch system is. I was hoping someone would say that they've run MS like that.

04-04-2021, 10:25 PM	#4
bobxyz Board Member Join Date: Aug 2014 Location: Boulder CO	MicroSquirt is easy - connect the Opto +/- wires to the 2 tabs on the coil -/+ (they cross Opto+ to - tab). CDI is the same thing as an add-on MSD red high-voltage multi-spark ignition box, not the factory Bosch Breakerless ignition. Once you want to go beyond Fuel Only, you'll need a LH2.2 distributor, or will need to modify the Turbo K-Jet distributor to lock down the vacuum and centrifugal advance mechanisms.