Cel Then Big Flame

[MacRS200]

Like it says above but a bit more detail - was sitting in 4th on the tip, floored it, car "kicked down", car took off as usual then CEL flashed on and a big orange flame came out the back. Same time the CEL went out, I eased off the gas and all back to normal. It has happened before, about twice, but not on this scale and the other times I did not notice a CEL. Tried to make it happen again but no joy so must be intermittent what ever it is.

I am thinking :-

1/ Dodgy spark plug

2/ Dodgy coil pack

3/ VVTi problem

4/ Sticky Exhaust Valve, even bigger

Would think that 1, 2 & 3 would cause it to throw a CEL but not 4?

Anyone got any other ideas.

TIA

[Adie]

I'm assuming the flame is due to the build up of unburnt fuel which has probably built up to throw the CEL on. Then with burning it with a backfire, clearing the CEL.. and this is caused by??

I'm assuming the flame is due to the build up of unburnt fuel which has probably built up to throw the CEL on. Then with burning it with a backfire, clearing the CEL.. and this is caused by??

Maybe 1 or 2 or both if the fuel is not being burnt properly.

How long has it been going on for? Just recently?

[MacRS200]

I'm assuming the flame is due to the build up of unburnt fuel which has probably built up to throw the CEL on. Then with burning it with a backfire, clearing the CEL.. and this is caused by??

Maybe 1 or 2 or both if the fuel is not being burnt properly.

How long has it been going on for? Just recently?

I am assuming the same as you mate unburnt fuel getting in the exhaust. Only 2 causes I can think of are exhaust valve open at the wrong time or no spark to burn the fuel in the cylinder. As I have no cats and the pipe is basically straight through I blows out the tail.

Like I said it has happened in the past on odd occasions and I just ignored it. Before I did not see a CEL though.