Unfortunately the tech assumed it skipped a tooth because of the uneven cranking sound, backfiring and weak or no spark from the coil. He did not remove the connectors for the injector nor the coils and so when cranking it would sound like it had a compression problem. If he had disabled the fuel and or coils as I did the engine cranking sound would have pointed him away from a timing problem.

This system uses waste spark ignition, meaning it fires one cylinder at compression and the running mate during exhaust. My theory is because it still have fuel going into the cylinders which did not get ignited during compression it gets ignited when it goes into the exhaust manifold via the other cylinders during exhaust stroke. Poor ignition is also a cause for backfire. Because lpg burns at a slower rate it is possible that it is still combusting when the exhaust valve opens.

@@forkliftgeek10 Thanks! Didnt know about the "waste spark igintion". So the fuel could get ignited via the exhaust manifld ..by heat then? Also other reason for backfiring was interesting to know. Q: I am just about to look for job ... how did you get yours?

I was a forklift operator when my forklift broke down and a mechanic went in. He opened it up and I saw that most of the parts I recognized and know how it worked, so he gave me a calling card and told me to apply as an apprentice.

Most of it is by taking captures of normal as a reference. When it comes to electrical circuits understanding of the component you are testing and how voltage and current behaves through that is critical in determining what is normal.

Thanks for the advice! I am a technician for an MCFA dealer. I am looking for ways/tools to make more accurate diagnosis. Hopefully the Picoscope helps.

Picoscope 6

Ignition timing is definitely suspect.

Correct , or misplaced wires to distributor, check firing ORDER

Picoscope

On the right side of the steering column

Just message me on Instagram or Facebook.