THE PORTAL HUB - Pinzgauers, Haflingers, Volvo 303s and more!

When a truck appears to be running on three cylinders I usually pull plug wires off one by one to see which cylinder is not working. With Pinz SSI you can damage the system by running with a plug wire disconnected. Is there another way to see which cylinder is not working.

I would think the easiest would be to get one of those infrared temp guns and see if there is a difference in the exhaust temperatures.

Yes, from under the truck point an IR thermometer at each of the exhaust manifolds -- it'll be clear which one isn't pulling its weight.

On the "pull a plug wire test", the easy answer is to connect each of the wires in succession to an extra spark plug held against the engine. Start/Run the engine and note the RPM, then switch to the next cylinder. If one isn't firing. you'll see no spark on the plug running outside the engine, and you'll see a difference in the RPM.

Back before everybody relied on fancy computerized tools, we used ignition tester. Hold hold it up to the each cable and it would illuminate with each spark.

David Dunn wrote: ↑Sat Jun 25, 2022 7:11 pm Back before everybody relied on fancy computerized tools, we used ignition tester. Hold hold it up to the each cable and it would illuminate with each spark.

I'm guessing those wouldn't work very well with the shielded factory wires. I confirmed my inductive pickup timing light was unimpressed by the factory wires, and thus we used a short length of unshielded wire at the distributor cap to enable using a timing light on the Pinz.

But....this person has aftermarket unshielded wires, so they could test for HV, but you might still have good HV pulse and a dead cylinder, but the tester is a good start. To the OP: maybe you can just borrow a traditional timing light with inductive pickup from someone if you don't own one already.

Just put your hand on the cylinderhead...if its cold its not working.

Easy solution for checking spark regardless of system is use a spare spark plug ground to valve cover between the fins. Observe for spark while cranking.
Quick way to find a bad wire or verify spark.

I still use wax and rub it on the exhaust headers while engine is running. It will be quickly apparent which cylinder is not firing.

Being a wasted spark system, the engine would lose 2 cylinders if the ignition system was at fault, not one. Something else is wrong, several things could cause this.