missfire gq 4.2 petrol

The problem I am having is that whenever I am driving, it has a random misfire! As it misfires the Tacho meter fluctuates, the needle quickly drops and returns as if the power is being cut and turned back on very quickly. this causes a back fire sometimes and makes it quite hard to drive. It can happen when the engine is hot or cold, under load/no load but seems the worst when I am coasting like slowing down for an intersection, that's when it flicks constantly!

SORRY I TOOK THIS FROM AN OTHER SITE as this is happening to my patrol

Hi mate, are you running LPG?

no just petrol

Ignition/injection problem on one of the cylinders?? Not much else I can offer - have you swapped out the plugs and leads??

Ok, could be a few things. what have you checked and can tick off as being ok?

Just throwing some ideas out there...

Hopefully someone else can throw some other things to check

• Check fuel filter to make sure It's not blocked
• Check spark, replace spark and if no success just keep spare spark anyway
• Timing?
• Check the points
• Check the coil

Just some basic checkovers but out of that list there's a good chance you'll find something there.

Yell out if you need help checking those or clarification, etc and let us know how you go.

check conections around balist and coil ensure the coil bracket on the coil is earthed properly and tight check for cracks in dizy cap

Hi,
As said above check all ignition and fuel, my GQ does the same thing about every 10,000-15,000klm, mine is running LPG, but normally easy to fix, quick change of points, sometimes only just need a quick rub with fine wet/dry sand paper. Reset timing and problem useually fixed. One of the things on my wish list is to replace cra*py points with petronics or some type of electronic ignition system. Hope you find the problem.

Mine was doing the same changed every thing (coil, leads, plugs, points,) and it still had the problem it ended up being the small earth wire inside the dizzy so I made up a new one and problem solved. hope this helps.

Quote:

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Originally Posted by WHITEGQ

Hi,
As said above check all ignition and fuel, my GQ does the same thing about every 10,000-15,000klm, mine is running LPG, but normally easy to fix, quick change of points, sometimes only just need a quick rub with fine wet/dry sand paper. Reset timing and problem useually fixed. One of the things on my wish list is to replace cra*py points with petronics or some type of electronic ignition system. Hope you find the problem.

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I Have the Pertronix ignition and sometimes i wish it was points purely because there is no sure way of checking the module for problems a set of pionts you can turn the motor over and see the points are sparking no such luck with a module makes aa big differance in the bush between driving home and being towed home !!

If it still running a breaker point system? thats the first thing to be checked & it is also the cheapest at around $10.... Not hard to fit & im tipping its where the problem lie anyway.