1980 Nissan



January, 7, 2007 AT 12:36 AM

I'm getting misfiring whenever I rev the engine. At idle, and revs up to about 2500 RPM, it is fine. As soon as it starts reving higher, it chokes and clutters and misfires badly (sounds like nearly all clyinders at times). Have replaced spark plugs, fuel filter, distributor cap, rotor. Has had timing done. New coil, condensor, leads were put in no more then 9 months ago - and has been running well until this problem arose few weeks ago. Please help!


5 Answers



January, 7, 2007 AT 2:18 AM

Is this a Carb or EFI system also the type of Ignition system

Try this remove the PCV valve-the rpm should drop atleast 50rpm when plugged and raises when unplugged. No changes inspect valve and vacuum passages.

Also perform a fuel pressure test.

Double check all connections at plug wires at spark plug and distributor to include the coil wire from coil to dist. Cap.

Does it have a mechanical vacuum advance?

Spark plugs is it the correct type and heat range.

HTH Good Luck!



January, 7, 2007 AT 4:18 AM

It is a Carby system.

Tried removing PCV tube and RPM did increase when tube was removed.

Tested fuel pressure - seeing its gravity fed, I pumped some compressed air down the line backwards to possibly blow out any gunk. Didn't seem to make much difference and pressure still seems good.

When I was checking coil, leads, etc, I noticed the condensor was loose (and therefore not grounding properly). Once I corrected this - it is now working 100%! Could this indeed cause the problem I was having, or did I perhaps knock something else while I was hunting around?



January, 7, 2007 AT 5:24 AM

Yes it will-the condenser absorbs energy ( voltage) to help the coil to build the magnetic field to induce the secondary surge on the secondary windings to fire the plugs. And also provides noise suppression.

Also on a Contact Points ignition system it helps prevent the points from burning up due to arcing.



January, 7, 2007 AT 5:52 AM

Much appreciate your help - thanks very much! You have helped solve a 2 month niggly problem : )


Service Writer

January, 7, 2007 AT 8:24 AM

Strike another one up for the good guys : D

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