LUVTruck.com

Hi guys ...haven't posted for a while. I have a77 stock Luv.160,000 miles. Been driving lots of miles out of state. My engine has a random miss at about 55 to 65 mph. It seems electrical and is a sharp jolt to the LUV as it rolls along. I put in new plugs and wires etc. in Jan 08. Thought it was cured, but no. In June I took it to Austin and found on the way that If I turn on the lights, the miss goes away!! It sometimes is a pop-pop-pop and seems definately electrical to me. It can be giving me trouble and right in the middle of the pops, I turn on the lights and it quits. Others have witnessed this. So, I put in a new dizzy/points as it was somewhat worn but, still missing. Recently, I isolated the system to eliminate all the other wiring by adding a switched line from the battery direct to the ballast resistor. Still missing--turn on the lights, it quits. Next I unplugged the ballast by-pass relay--no luck, still missing. I ohmed out the coil and ballast resistor and they are within tolerances. I went over the wiring diagram and the only thing remotely connected(i.e. ign and lights) is a ground wire going through the by-pass relay but now that is disconnected. The coil appears firmly mounted to the fender well thus well grounded. Still missing. I'm pulling out what hair I have left!! Anyone have any ideas??? Thanks in advance...Don.

Yep, that's a strange one!

So what's happening? Turning on lights does three things: lights up the road, puts a drain on electrical system, and causes regulator to sense that power drain and boost volts/amps from alternator.

Your problem is apprently ignition & electrical. Plugs are good, but voltage to points is an issue the way circuits are designed, and that comes by way of the coil, hint, hint, hint....

Check primary voltage to coil with engine running or with ignition in 'run' position. If it's close to battery voltage I'm going to guess you have a saturated coil, weak secondary voltage, needing replacement. Almost any 12V coil will work as a test mule to see if things change.