Offroad-Express

Jumped in the surf this morning to go to work and it doesnt want to go. Has been sitting since friday.
It just winds over but no fire.
After a couple of attempts it backfired a couple of times.
Any ideas where i should start?
Cheers
Jade

Check for spark air n fuel that's all you need to have it run.

Ashohman wrote:Check for spark air n fuel that's all you need to have it run.

If it were that easy auto sparkies wouldnt exist.

if its back firing it has fuel and spark, just not at the right time.

crank angle sensor, clearly it aint squirting and firing when it is supposed too. and yes, they do stop working just like that. one day fine, next day, screw you walk to work.

Be great if it was that easy ashoman.
Thanks crash i thought cas would throw a fault code so it had me stumped. Also thought they gave a bit of warning lol.
Looks like i need a cas then lol

Auto sparkies are over rated mate.

Check you have power to the injectors also try unpluging tps sensor. Check for damage to crank angle sensor as it is routed behind acc belt and crank wheel.

Will disconnect tps tommorow and see what it does, at the moment it just turns over for a while then kicks back and backfires.
So im guessing the wasted spark set up would cause it to backfire?

jade_l wrote:Will disconnect tps tommorow and see what it does, at the moment it just turns over for a while then kicks back and backfires.
So im guessing the wasted spark set up would cause it to backfire?

no, wasted spark fires twice a revoloution , but still just after tdc. thats the only difference...as said before, if its back firing it still has fuel and spark just not at the right time.

Yeah i understand i have fuel and spark.
My understanding of wasted spark was that one cylinder is ignited while compressed and another "empty" cylinder is also ignited simultaneously.
I was thinking that since it wasnt sparking on time the "empty" cylinder may not be empty because the fuel in that cylinder wasnt burnt in the previous cycle.
If that makes any sense lol

You are correct, but even if there was unburnt fuel on the exhaust stroke it still shouldnt back fire. Backfire is caused by ignition while the exhaust port or ports are open which by deduction says incorrect ignition timing.

Even with wasted spark the exhaust port wont be open yet when it fires...

Any more bright ideas? Put a new cas in today still not running 100% has a miss when i put my foot down not too bad at light throttle
I also tried the tps of my old motor and it seemed to make buggar all difference.
Changed dfi coils and leads of my old motor which was running fine until it decided to through a leg out of bed

I got it to run (very poorly) before i put the new cas in also.

check spark plugs and leads ive had mine fail and cause a miss at higher rpms or under load.

check the gap on all your spark plugs too should be a 1.5mm gap

I will swap back to my old leads and see how it goes. The ones on it at the moment where near new when old motor blew up.

Idleing OK but missing under load sounds fuel related??

Cheak plugs, if you had a starting problem and wound it over not firing it doesn't take much to foul plugs now unfortunately

module under coils go's haywire on these. series one or 2 engine? does it have a clicking noise in front. harmonic balancer rubber slips and can upset crank angle sensor a bit. tho not usualy causing miss tho.

Got her sorted i think. Cas was first problem and i think i may have cracked a plug when i was testing for spark, its a series 2 vr engine i tried different dfi aswell.
Done 300kms this weekend away hunting and its ran pretty well.
Just has a slight miss every now and then at very light throttle, like when you slow down from passing a car to 100 and gently put the gas on it will sometimes give a wee hiccup.