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[Kevin Wood]

Hmmm, I see there are a few threads currently about 2.5 v6 misfires

Hope the others aren't as bad as mine

Dropping like flies.

Kevin

[TheBoy]

Right, good spark on No6.

Compression on No6 was 4 bar initially when tested, went up to 18bar () when a bit of oil popped down inlet.

[Entwood]

Wonder if you have a "ring" problem .... (waits for unsuitable comments !!!  )

[CaptainZok]

Wonder if you have a "ring" problem .... (waits for unsuitable comments !!!  )

Fnar fnar.

[Kevin Wood]

Right, good spark on No6.

Compression on No6 was 4 bar initially when tested, went up to 18bar () when a bit of oil popped down inlet.

How much oil did you put in?

At least there is compression, and remember the silver bullet did exactly the same? EDIT: OK, not 18 BAR but it dropped considerably after a misfire.

I wonder if you were a little heavy-handed with the oil and it's taken up some of the combustion chamber volume. Either that or the pot is full of fuel. :-/

Any sign of a leaky injector with intake off?

Kevin

[TheBoy]

Right, good spark on No6.

Compression on No6 was 4 bar initially when tested, went up to 18bar () when a bit of oil popped down inlet.

How much oil did you put in?

At least there is compression, and remember the silver bullet did exactly the same? EDIT: OK, not 18 BAR but it dropped considerably after a misfire.

I wonder if you were a little heavy-handed with the oil and it's taken up some of the combustion chamber volume. Either that or the pot is full of fuel. :-/

Any sign of a leaky injector with intake off?

Kevin

I may have been heavy handed - was guessing at a teaspoon but bloody well sneezed. Probably nearer a tablespoon.

[feeutfo]

Right, good spark on No6.

Compression on No6 was 4 bar initially when tested, went up to 18bar () when a bit of oil popped down inlet.

How much oil did you put in?

At least there is compression, and remember the silver bullet did exactly the same? EDIT: OK, not 18 BAR but it dropped considerably after a misfire.

I wonder if you were a little heavy-handed with the oil and it's taken up some of the combustion chamber volume. Either that or the pot is full of fuel. :-/

Any sign of a leaky injector with intake off?

Kevin

I may have been heavy handed - was guessing at a teaspoon but bloody well sneezed. Probably nearer a tablespoon.

gaw steady on, almost enough to hydro lock, if it goes over tdc with a full combustion chamber of oil it'll lift the head off and streatch the head bolts

[TheBoy]

Right, good spark on No6.

Compression on No6 was 4 bar initially when tested, went up to 18bar () when a bit of oil popped down inlet.

How much oil did you put in?

At least there is compression, and remember the silver bullet did exactly the same? EDIT: OK, not 18 BAR but it dropped considerably after a misfire.

I wonder if you were a little heavy-handed with the oil and it's taken up some of the combustion chamber volume. Either that or the pot is full of fuel. :-/

Any sign of a leaky injector with intake off?

Kevin

I may have been heavy handed - was guessing at a teaspoon but bloody well sneezed. Probably nearer a tablespoon.

gaw steady on, almost enough to hydro lock, if it goes over tdc with a full combustion chamber of oil it'll lift the head off and streatch the head bolts

Thats why plug was out when I turned it over

[mrjimbo]

4 bar (without oil) is not much, it's only 57psi. I would be looking for 10 - 12 bar(145 - 170psi) at least.

What are the the other cylinders reading ?

If you have 2 cylinders next to each other with low readings then i would say its head gasket related, blowing between these 2 cylinders.

If a complete bank is giving low readings then i would say its more likely a cambelt/pulley problem (possibly a sheared woodruf key) the pictures look as the timing is OK but if the woodruf key has sheared the pullies will still look as though they are in the right place but the cam could have turned inside the pulley.

If it's only the one cylinder with low reading it could be a snapped cam, it's not unheard of and no6 is right on the end aswell thus causing piston and valves to come together resulting in a couple of bent valves. One of the hydraulic tappets may have split and temporarely become wedged in the tappet bore again this could cause a bent valve (the Rover SDI's with the inline engine suffered from this, especially the 2.6) or it may have dropped a valve due to collet or spring failure.

The best thing to do is test the compressions on all the cylinders on that bank and see what you have and then take the cam cover off that bank and see what you have then.
 
I hope it's not too serious but it does sound more mechanical than fuel or spark problems.

[TheBoy]

4 bar (without oil) is not much, it's only 57psi. I would be looking for 10 - 12 bar(145 - 170psi) at least.

What are the the other cylinders reading ?

If you have 2 cylinders next to each other with low readings then i would say its head gasket related, blowing between these 2 cylinders.

If a complete bank is giving low readings then i would say its more likely a cambelt/pulley problem (possibly a sheared woodruf key) the pictures look as the timing is OK but if the woodruf key has sheared the pullies will still look as though they are in the right place but the cam could have turned inside the pulley.

If it's only the one cylinder with low reading it could be a snapped cam, it's not unheard of and no6 is right on the end aswell thus causing piston and valves to come together resulting in a couple of bent valves. One of the hydraulic tappets may have split and temporarely become wedged in the tappet bore again this could cause a bent valve (the Rover SDI's with the inline engine suffered from this, especially the 2.6) or it may have dropped a valve due to collet or spring failure.

The best thing to do is test the compressions on all the cylinders on that bank and see what you have and then take the cam cover off that bank and see what you have then.
 
I hope it's not too serious but it does sound more mechanical than fuel or spark problems.

Other 4 I could get to read in the normal 12-14bar range. Couldn't get to 5 due to fuel lines (easily removed I know, but I am more interested in no6, as that is the cylinder not firing).  4bar shows there is no valve damage, but potentially suffering bore wash (remember, its been started a number of times now, and that pot is not firing), hence the oil trick.

[Kevin Wood]

It would be interesting to re-test that cylinder after turning it over a few times on the starter. See if it drops back to a sensible reading as the oil disperses or drops to a very low level again.

My feeling is that it's just bore wash, as this is exactly the issue we had with one cylinder on the MV6, and there wasn't even an underlying cause of misfire there, in the end. We'd just started it for short intervals until one of the plugs fouled due to the rich mixture.

You wouldn't have any compression with a failed cam as the valves would either have been chewed up, or would be closed, in either scenario you won't get any compression.

My suspicion lies with the fuel injector on that cylinder.

If all goes well, I guess you'll have an entire spare intake manifold to chuck on after this weekend, to eliminate that.

If I remember I'll bring my injector circuit tester too.

Kevin

[TheBoy]

It would be interesting to re-test that cylinder after turning it over a few times on the starter. See if it drops back to a sensible reading as the oil disperses or drops to a very low level again.

My feeling is that it's just bore wash, as this is exactly the issue we had with one cylinder on the MV6, and there wasn't even an underlying cause of misfire there, in the end. We'd just started it for short intervals until one of the plugs fouled due to the rich mixture.

You wouldn't have any compression with a failed cam as the valves would either have been chewed up, or would be closed, in either scenario you won't get any compression.

My suspicion lies with the fuel injector on that cylinder.

If all goes well, I guess you'll have an entire spare intake manifold to chuck on after this weekend, to eliminate that.

If I remember I'll bring my injector circuit tester too.

Kevin

New inlet was my next course of action

[TheBoy]

Oh, and inlet valves look to be moving as expected on all 6 cylinders.

Which is handy, as those 3l cams are worth £100-£150 when I break the car

[Marks DTM Calib]

Give the fuel injection loom on both halves a quick look over near the injector multiplug

[TheBoy]

Give the fuel injection loom on both halves a quick look over near the injector multiplug

The wiring looks OK, but not had the connector apart yet (it was fighting back, so I went in for a cuppa, sat down in front of OOF, and that was another evening gone )