Intermittent cyl 2 misfire after head rebuild
#1
Intermittent cyl 2 misfire after head rebuild
This has happened three times in our first 800km (500 miles) since rebuilding the head. I swapped the cyl 1 & 2 coils after the second time but it hasn't followed the coil. Spark plugs were new in January.
It can be a bit lumpy idling when warm (it feels like too low rpm).
New battery, water pump, thermostat, eccentric shaft sensor, vanos solenoids, oxygen sensors, timing chain + guides.
It's a 2008 R56 Cooper N12 justa.
Wondering if anyone who knows what they are looking at can see a pointer in this freeze frame data:
It can be a bit lumpy idling when warm (it feels like too low rpm).
New battery, water pump, thermostat, eccentric shaft sensor, vanos solenoids, oxygen sensors, timing chain + guides.
It's a 2008 R56 Cooper N12 justa.
Wondering if anyone who knows what they are looking at can see a pointer in this freeze frame data:
Last edited by craney; 08-01-2019 at 04:39 AM. Reason: title typo + added car model
#3
This was while driving at 40km/h.
Didn't do any investigating tonight. Had planned to do a post rebuild oil + filter change before i disappear for two weeks away for work (my wife drives the car). We've tried to keep it under 3000rpm since getting back on the road. The oil looked OK with no particles in it (phew).
I can do a hot engine compression test after work tomorrow.
The rebuild problem was zero compression on cyl 4 - turned out to be four collapsed valve lifters.
Didn't do any investigating tonight. Had planned to do a post rebuild oil + filter change before i disappear for two weeks away for work (my wife drives the car). We've tried to keep it under 3000rpm since getting back on the road. The oil looked OK with no particles in it (phew).
I can do a hot engine compression test after work tomorrow.
The rebuild problem was zero compression on cyl 4 - turned out to be four collapsed valve lifters.
#4
#5
#6
Ok, we need to get our part names squared away to ensure we're talking about the same thing. There aren't any "valve lifters" in the N12 cylinder head like there are in an over-head valve push-rod engine.
In the first picture below of the intake camshaft, item 8 is called a "roller drag lever" In the second picture of the eccentric shaft, item 10 is the "intermediate lever". On the intake side, the intermediate lever controls valve lift via the position of the DME controlled eccentric shaft. In the 3d picture, you see how the two pieces work together. With that out of the way, what actually collapsed?
The exhaust side doesn't have an eccentric shaft, so the roller drag levers are actuated directly by the exhaust camshaft lobe.
In the first picture below of the intake camshaft, item 8 is called a "roller drag lever" In the second picture of the eccentric shaft, item 10 is the "intermediate lever". On the intake side, the intermediate lever controls valve lift via the position of the DME controlled eccentric shaft. In the 3d picture, you see how the two pieces work together. With that out of the way, what actually collapsed?
The exhaust side doesn't have an eccentric shaft, so the roller drag levers are actuated directly by the exhaust camshaft lobe.
#7
Trending Topics
#9
#10
#11
#13
The reason I was asking was, the valve seats like to fall out of these heads. After one of mine dropped (500 miles after fixing the warped head), I replaced all of them.
http://www.engineprofessional.com/TB/TB113017-1.pdf
http://www.engineprofessional.com/TB/TB113017-1.pdf
Thread
Thread Starter
Forum
Replies
Last Post
F55/F56 Turbo Boost 3 cyl vs 4 cyl
Minnie.the.Moocher
F55/F56 :: Hatch Talk (2014+)
8
08-15-2016 03:56 PM
gchin
F55/F56 :: Hatch Talk (2014+)
3
02-11-2014 11:04 AM