captainbeaky
Active Member
OK, we are smashing our heads in on this one.
2004 Defender, 15p Engine Cylinder head has been replaced at some point with a 2006 dated head.
Car came in with a cam lobe badly worn (on injector cam lobe) Fixed that (replaced cam and injector cam follower/tappet assy).
Found debris in sump, so we checked the bottom end - found damage, so fitted new crank, mains, big ends, oil pump and seals.
Didn't remove pistons, but bores and crowns are mint, piston slop in bore is minimal.
Engine starts on the button and idles beautifully even from stone cold, cylinder balances nice - less than 5. No smoke on start and idle at all.
All's good right? Err no.
Apply a little throttle to raise the revs to about 1500 rpm, and a cylinder or two drop out, and billows white smoke that smells of diesel, cylinder balances go bezerk on cylinders 2 and 3. This is no load.
Here's what it's not (either fitted a new part or a known good part, pretty much in this order):-
Scoped out the Crank signal - it's OK - no noise.
Throttle pedal signal looks OK - linear and contiguous action.
We are now chasing possible electrical gremlins - harness damage?
The harnesses that run alongside the gearbox have been crunched a bit by some previous work, so we pulled the engine harness out (Red plug from ECU into the engine bay) and found no obvious trauma, and all the engine harness wires buzz out ok.
Next step is to check the harness behind the dash into the engine bay...
But this really is scraping the barrel...
Starting to lose my sanity - I cant think of what it could possibly be that would cause this weird misfire, but give an absolutely "perfect" idle (that we haven't already checked).
Any ideas?
TIA...
Mike.
2004 Defender, 15p Engine Cylinder head has been replaced at some point with a 2006 dated head.
Car came in with a cam lobe badly worn (on injector cam lobe) Fixed that (replaced cam and injector cam follower/tappet assy).
Found debris in sump, so we checked the bottom end - found damage, so fitted new crank, mains, big ends, oil pump and seals.
Didn't remove pistons, but bores and crowns are mint, piston slop in bore is minimal.
Engine starts on the button and idles beautifully even from stone cold, cylinder balances nice - less than 5. No smoke on start and idle at all.
All's good right? Err no.
Apply a little throttle to raise the revs to about 1500 rpm, and a cylinder or two drop out, and billows white smoke that smells of diesel, cylinder balances go bezerk on cylinders 2 and 3. This is no load.
Here's what it's not (either fitted a new part or a known good part, pretty much in this order):-
- Injector Harness (This was looking dirty in the sockets so we changed it while we had the lot out - ECU harness is clean as a whistle)
- Injectors (Changed them out for a known good set with new LR seals)
- Fuel filter ( we fitted new filter and air bleed and one way valve - all were faulty)
- Fuel pump and Pressure regulator (Fuel pressure is bang on at 4.2 bar - rising to 5 bar when engine running)
- Crank Sensor (Tried a known good one - also scoped the signal)
- DMF (Checked it when we had the engine out - worn but good)
- ECU (Tried a known good one - albeit from a disco - also to check that it wasn't the tune)
- Cylinder head (Put a known good one on - we were thinking crack in the head)
- Since we changed the head, it's not likely it's a pumped up hydraulic lifter.
- Cylinder head gasket and dowels (see above!)
- Turbo (We are running it without the I/C at the moment while we are trying to figure this out, and it does it with the turbo not connected to the intake, so it's not oil from the turbo or an EGR problem)
- EGR has been deleted anyway.
Scoped out the Crank signal - it's OK - no noise.
Throttle pedal signal looks OK - linear and contiguous action.
We are now chasing possible electrical gremlins - harness damage?
The harnesses that run alongside the gearbox have been crunched a bit by some previous work, so we pulled the engine harness out (Red plug from ECU into the engine bay) and found no obvious trauma, and all the engine harness wires buzz out ok.
Next step is to check the harness behind the dash into the engine bay...
But this really is scraping the barrel...
Starting to lose my sanity - I cant think of what it could possibly be that would cause this weird misfire, but give an absolutely "perfect" idle (that we haven't already checked).
Any ideas?
TIA...
Mike.