Missfire and popping

Had new plugs and leads 2 weeks ago and all sparking well.

Fuel filter or pump if it isn't air. (Plenty of fresh fuel in tank i presume)

where are you based?somebody might be local to have a shufti.

I am based in Mansfield. Anyone close?

I find these engines sensitive to the make of spark plug. Mine had a miss fire, turned out the champion spark plugs were no good. Even with new ones out the box. Fitted Brisk plugs, problem sorted.

I've had many dodgy Champion plugs over the years - I only buy NGK now.

popping and spitting back through the intake is (usually) caused by,wrong cam timing or incorrect preload on the lifters,ie valve being held open,a compression test should reveal this,air intake leak,incorrect firing order on the ignition leads,check the order carefully bearing in mind that no1 cylinder is front right.that may be obvious but i had somebody install ignition leads using front left as no 1,one burnt out starter motor later,(lots and lots of cranking) i happened along

Just an update. Tried everything suggested so far (except diag which is booked for Saturday) and still the same. Rangie will sit and rev lovely on the drive but when put into drive or reverse power is lost and no feeling through the accelerator. Any more guesses people???

Lots of good advice on here, sounds like your making good progress with diagnosis at least. Hopefully the diagnostics will put you on the right track.
Had a similar issue with mine, though the revs would flutter in neutral. But under power there was major power loss and backfiring. Turned out to be the crank sensor, just bear in mind when it's on the diag that it'll throw up a cam sensor code if this is the problem.

Ok. Just an update. Today the diagnostics showed up the maf which was obviously an old fault as when cleared and reset it didn't show up again.
So me and my brother stripped the polonium chamber off, coil pack and leads and all air hoses. Cleaned everything down, checked for splits in hoses and put everything back. The car started and revs will now sit at 2000 rpm??? Car still misfires and pops and lacks power.
So we removed drivers side exhaust manifold and low and behold cylinder number 8 pipe was completely blocked...... Could this have been my problem all along???

Blocked???

qwertz said:

Blocked???

Click to expand...

Yep. Blocked solid.....

ibateman said:

Yep. Blocked solid.....

Click to expand...

Blocked with what? Was the gasket back to front or was the exhaust port full of something?

jt_armstrong said:

Blocked with what? Was the gasket back to front or was the exhaust port full of something?

Click to expand...

Gasket was fine. Exhaust was solid with carbon deposit.

ibateman said:

Gasket was fine. Exhaust was solid with carbon deposit.

Click to expand...

Really????

Holy Feck that cylinder has been seriously overfuelling then...could be a leaky injector, or valves not seating properly....

Never heard of that before....

Saint.V8 said:

Really????

Holy Feck that cylinder has been seriously overfuelling then...could be a leaky injector, or valves not seating properly....

Never heard of that before....

Click to expand...

Sounds like he's got a 2 stroke version

I've just had a similar problem with mine - a loud popping sound on acceleration and lack of power.

Took it to my local indie and after stripping the engine down bit by bit the culprit was found. The camshaft hardening process had not worked properly on one of the cams which had worn it from a pear shape to a round shape. This meant the exhaust valve was not operating, crap built up in that cylinder and from what I understand the gasses had blown the head gasket to escape. I had not lose of oil or water or mixing of them.

Apparently this is not a usual thing to happen with the camshaft but not unknown.

So, new gaskets, both heads skimmed, a new camshaft and a lighter wallet later, it is all fixed and like a new car.

I had a SD1 head where one port was 1/2 blocked with aluminium from when it was made.
really crap quality control in the day.