missfire gq 4.2 petrol

[sambar308]

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

[AB]

Hi mate, are you running LPG?

[sambar308]

no just petrol

[Bigrig]

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

[AB]

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.

[timbar]

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

[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.

[Benno7]

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.

[timbar]

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.

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 !!

[patch697]

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.