what in the hellls going on with my v6

[cracker]

last few days my vn v6 has been giving me the ****s,
it started out with a very bad miss which got worse.
iv done a compression test all good around 150
new leads, new plugs, changed coils and dfi module, new map sensor, new fuel pump, new fuel filter, new air filter, even a brand new loom, even used jumper leads to check that the earth is all good, changed the ecu u over changed the map sensor over for a non two bar and a stock computer still no change,
when it does run get lots of back firing out the intake and exhuast,
its gone from running lovely to terrible for no reason its got 1/4 tank of fuel and its shell v max, the injectors are firing because i removed them to check they were, and u can smell the fuel
iv got no idea what could be wrong at all its driving me nuts! any suggestions please!

[PaRaDoX]

coil packs maybe?

reinsepct the leads for fouldness

[cracker]

im thinking maybe weak spark what would cause this?

[Pub247]

harmonic balancer? sounds like the timing is way out. Might have spun the balancer.

[cracker]

balancer is fine hasnt seen any high rpm or wot at all its on a base tune nothing over 40% throttle or 3000rpm and it was running very nice

[Rhino Racing]

Crank angle sensor?

[RockyVX]

have you checked the exhaust for blockages?
that could be it

[Blown V6 Hatch]

Could have the same issue that Paradox had a while back. Stuffed keyway on the crankshaft.

[vncruzr]

your cat convertor might be blocked or check the gaskets on your throttle body also check your throttle position sensor and your air idle valve on the throttle body. also might be worth checking your temp sender or the earth to your temp sender which i think also earths your coil. it sounds to be either earth/electrical or its getting a false reading from and engine sensor.

[doms3]

I had something similar years ago ,I fitted after market leads and it ran like a pig put genuine holden ones back on and ran great .

[andyman]

id check that the key way on harmonic balncer hasnt sheered of, from you saying 'when it does run get lots of back firing out the intake and exhuast' that say its firing not in time, so pull the balancer off and inspect it,

im sure you know the balancer has to be in the right spot so the crank angle sensor is picking up the right impulses relative to the engines cycles so the spark is timed at the right moment

[cracker]

yerp balancer has never been off iv never touched the short motor it came from a mates vr calais done 170 000km the balancer will be coming off tomra and a new cas sensor put in.
as for the earth its very good iv had jumper leeds conected to everything it has a very effective earth ( negavite ) its very sure its electrical( lucky im an apprentice sparky gorhh)
manifold gaskets are all good, and blocked exhuast seems unlikely as its not that old and was in good condition when install also being full 3" the whole way it would be pretty hard to block thanks for all ur suggestions they are all very appreciated