I'll explain my situation and hopefully you can shed some light on why this is happening.
I have a 91 JDM vr4.
I have boost leak tested it many times but only to about 20psi. I have just increased my boost level to ~26psi and thought I better do a boost leak test to above that level to ensure I wasn't missing any other high pressure leaks.
I found a couple and fixed them. (Throttle body gaskets and biss o-ring).
While resetting my biss screw to hit 30 on the isc position I though it would be a good idea to check my base timing.
Hooked up the timing light and I can only get a clear and consistent light that actually revealed my crank pulley marks from the plug wire going to cylinder 4! (4 being at the thermostat end of the engine, furthest from the timing belt)
When I connect the timing light to the plug wires leading to cylinder 1,2 or 3 I get multiple strobes and cannot see the crank pulley marks anywhere even when moving the cam position sensor both ways until the engine start to stumble.
The car runs great with setting the timing to 5 BTDC off plug wire to cylinder 4 and has been dyno tuned to 250kw (335hp) in that setting.
I certainly don't think that my timing is out but why can I not get a good timing strobe from the cylinder 1 plug lead?