Anyone know how to trigger off of VR?

[seth1001]

I've given up on getting RPM from the coil (-) on my 1980 280zx. It just won't work. So now I'm going to try and trigger it off of the reluctor. Does anybody know how I'm supposed to get to that thing? And how I'm supposed to wire it up? I've never messed with the dizzy before so I'd like to know what I'm looking for before I go digging in there. Some pictures would be great. It's an N/A...by the way. Thanks.

[mobythevan]

If it was me I would just put an 83 zxt dizzy on there and use the optical CAS from it to trigger megasquirt and then run fuel and spark. That setup has been proven many times over. I wouldn't waste the time to mess with a VR dizzy setup just to run fuel only. (my two cents)

[NewZed]

If you go through this page, using your browser to search for "VR" you'll find several options. http://www.megamanual.com/v22manual/mwire.htm#ignition

 

The two wires inside the distributor are your positive and negative leads to the variable reluctor. There's a drawing on page EL-27 of the FSM - pickup coil assembly. I am fairly sure that you could run a circuit in parallel to trigger Megasquirt, while leaving your ignition module wiring alone. But I could be wrong.

 

The reluctor voltage ranges from very low to very high though so you might have the same problems with its signal as you're having with the coil negative. It is susceptible to noise also. You're just trading one voltage signal for another. The coil output trigger should be easier.

 

 

Full disclosure - I don't have Megasquirt but I do like to get into these problems so I'll know it better later, if I ever get my own. These are just places to look.

[seth1001]

It should be easier but apparently it's not. But looks like the VR setup isn't working either. It's really starting to piss me off. I've got the thing working fine on the stimulator and the spark is working fine on the car...I just can't getting any damn RPM signal to the MS. Also the FSM doesn't identify which wire is positive and which is negative...but it says the green wire goes to the "spark timing signal monitoring circuit" so I figured that was the one...but it didn't work.

 

Moby: my logic is that if I can't get this thing to work on "fuel only", there's no reason to think it will work as fuel and spark. Plus I really don't like working with distributors because my understanding is not good enough to not destroy the engine while I'm dicking with it...and changing the distributor has got to be harder than getting this thing to work...but that balance shifts with every failure.

[mobythevan]

I can understand where you are coming from. The only thing I want to add is that triggering with a VR signal is the single toughest thing to do with megasquirt installs. I avoid it at all costs, but I'm a whiner

 

BTW, your coil will have a marking that shows which post is positive and negative. Run your coil negative trigger wire all the way to the coil post if your not sure which wire out of the harness to use.

[seth1001]

Yeah I had it hooked up the post the whole time...Nothing is working to get an rpm signal to this thing...It's getting to the point where I don't understand how people are buying these things when it's such a pain in the ass to get them to work.

[Matt Cramer]

I'm convinced there is some sort of external wiring problem here - that is usually the case if the MS will get RPM on the Stim but not on the car. You might want to try going back to triggering off the coil, with the MS set up exactly the same way on the Stim as on the car and the input through the optoisolator.