Hey so I recently installed a PNP sytem for my FD RX7 and I have been fiddling with some base tuning but haven't done much because I wanted to confirm my timing first. So I finally found a timing light to borrow and I'm having some weird issues with it. On my leading plugs it flashes just fine but when I switch it to either of my trailing wires it doesn't flash at all. After some trouble shooting we noticed that it would flash for a second when we would pull the ground off the car, as if it would only fire as the light was discharging.

Now I have an Ultra M.D.I. ignition hooked up to my trailing coils and I'm wondering if this is the cause of my timing light issues and was wondering if anyone else has had this problem or if there was a work around. Thanks in advance!

 

MDI is basically a CDI ignition system.

Not all timing lights will work lights will work on CDI setups.

 

Thanks for the insight, I'm familiar with CDI's from my motocross days. Makes sense then why I'm having some issues.