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+--- Thread: Chronic misfire after short drive (/showthread.php?tid=7978)
Chronic misfire after short drive - JCLM - 29-08-2022
…new to this so hoping I’m posting properly.
I’ve a 1934 Ruby that’s giving me misfire grief. I moved to an accuspark distributor last year and initially all worked ok. Started to develop a misfire last week. Engine starts fine and initially runs fine. After a couple miles however the car misfires something chronic and sounds like a bag of spanners! It’s almost unable to be driven. I swapped out the trigger for a new one and again, same issue. Then moved back to the DK4 distributor yesterday and the same issue?? It’s leading me to think I’ve a bad connection in the ignition switch and making and breaking, but not sure. Wondered if anyone could give me a steer?
Thanks,
JC
RE: Chronic misfire after short drive - Ruairidh Dunford - 29-08-2022
In my experience, if the electronic units go, they stop completely.
Have you tried a different coil - ensure the new one has at least 2.4 ohms of protection if you continue to use the Accuspark unit.
RE: Chronic misfire after short drive - JCLM - 29-08-2022
Thanks,
Coil is measuring 3ohms. I’ll swap it out as suggested and see if that helps any.
RE: Chronic misfire after short drive - Bob Kneale - 29-08-2022
Before you do anything as drastic as dismantling the ignition switch, try substituting the ignition coil for a known reliable one. It could well be that the coil is breaking down after it warms up with high voltage flashover occurring.
Having just tracked down a chronic misfire on my '34 box I've just been through the same systematic process, and beyond. My problem was an excessively wide Exhaust tappet (202 thou)!
Good luck with your endeavour.
Bob
RE: Chronic misfire after short drive - JCLM - 29-08-2022
Thanks Bob, appreciate the insight.
RE: Chronic misfire after short drive - John Mason - 29-08-2022
Hi JSLM, You could also have misfires if you have a failing condenser that fails when hot. Also a bad plug that fails when hot although I doubt the plug though as your car would just run on three cylinders. Not enough to make it undrivable.
John Mason.
RE: Chronic misfire after short drive - JCLM - 24-09-2022
…solved! Finally got a chance to sort the issue out. It was a combination of a faulty coil and poor ignition contact in the switch. Replaced with a new coil - improved immensely but still got odd intermittent misfire. Pulled the switch apart and it was filthy. Cleaned it up, back together and all working fine.
Thanks for all the help…