X16XEL misfire

I recently bought a zafira with a blown engine, number one cylinder proper let go. It's a v reg car and I sourced a 2005 engine for it. This meant changing the cam pulley and sensor, crank sensor air con pump and bracket and inlet to the original ones. I've also put a new belt and pulleys on, new oil and filter as well.

Now on first start up it was a bit happy but by the time it got hot It shut up and now doesn't ever tap at all. On idle it runs really nice and if you build the res gradually it doesn't miss a beat at all yet when under load it misfires, it's pretty bad but it is drivable.

So far I've tried a new coil pack, new plugs and new crank sensor none of which have made a shed of difference. I have also had a tech 2 and snap on on it and the engine management light isn't on.

So suggestions people?

was the engine you sourced a good known engine Luke? what engine code is it as they never made an x16xel in 2005?

Well it doesnt rattle or knock at all and has 200+ psi on all cylinders so it's not bad. Not sure exactly on the code but the only difference is the management side of it but I've changed all of that

No air leaks inlet side?

Don't think so plus as these run a map sensor instead of a maf set up it should be less sensitive to stuff like that I think

Done a cylinder leak test?

Do you know why it let go in the first place or not Luke? might be related?

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Originally Posted by Andy

Done a cylinder leak test?

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No but didn't Particularly notice it going down whilst on the compression tester. Assuming I know what you mean

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Originally Posted by John

Do you know why it let go in the first place or not Luke? might be related?

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Not a clue, just looks like epic rod failure

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Originally Posted by burgo

No but didn't Particularly notice it going down whilst on the compression tester. Assuming I know what you mean

Not a clue, just looks like epic rod failure

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Well,if the wet and dry comp test were inconclusive then a leak test is next,to listen to leaks/if any from the,inlet,exhaust,expansion tank,dipstick. it can indicate broken valves or cracked combustion chambers etc.
Just another process of elimination mate:)

When I got between 200-220 on all cylinders dry I didn't even bother doing it wet as anything above 100 is generally considered ok

it is yes,but compression is only pistons,the leak test obviously eliminates valves and cracks,and head gaskets.Comp tests are generally only good for rings.

I guess. Thing is I forgot to say I took it up the road earlier and whilst accelerating in second it actually cleared and didn't misfire and pulled properly. It only really did this once though but that has me thinking it not a mechanical issue as such