[SOLVED] Cylinder 1 Misfire - P0301 / P0300 Mystery

[ard]

Am I missing something or is your Cylinder #1 damaged?????????

[pshovest]

Originally Posted by ard

Am I missing something or is your Cylinder #1 damaged?????????

Sure sounds like it. Bad rings, leaking/burned valve(s) or valvetronic problem.
This is a Valvetronic engine correct?
It would be nice if we could check compression with valves at max lift.
I recall reading about intermediate levers wearing and causing problems with valve lift particularly at idle when lift is the smallest. As I understood the problem, worn levers reduced valve lift causing roughness & misfires at idle due to incomplete cylinder filling. This could cause a false low compression reading. The fix was to raise the min valve lift using ISTA(?) as I recall. This higher valve lift gives the throttle plate a larger role in controlling the idle speed.

[Toothbrush]

Did a leak down test on while everything was open and had 100% leak on Cylinder 1 at TDC, but couldn't figure it out where it was going. So... hooked up the smoke machine with an air hose without the schrader valve and smoke (all of it?) almost immediately came out of Cylinder 4 through the spark plug tube. All of Bank 1 plugs are out.

Would this indicate bad rings? Or an exhaust leak and the smoke was just finding the first available path?

[Toothbrush]

Sorry for all the posts, maybe somebody will find all of this (thread) interesting.

Update - I plugged Cylinder 4 (threaded a hose on it) and all the smoke came out of the tailpipe. While that was happening I poked my camera through the oil filler cap to watch for any wisps of smoke inside the crankcase and never saw any.

Would this confirm exhaust leak of some kind? I'm hoping there's nothing bent or burnt. Going to run the second can of carbon clean through a little later today to see if I can't get things a little cleaner.

It's difficult to get good pictures of the exhaust valves, but I did open them up and took some pictures. I also watched the intake/exhaust as I hand cranked to see if anything looked out of the ordinary, but to my untrained eyes, nothing appeared to be wrong.

I have a few ideas on how to get some better, in focus, pics but we'll see.

[pshovest]

Originally Posted by Toothbrush

...........Replaced the valve stem seals last part of 2017 before it got cold. Had the misfire ever since.........

Can't overlook this coincidence.
I believe all of the cam/valvetronic hardware has to be removed to change the valve seals. Can it be reinstalled incorrectly so cyl 1 valve(s) don't close completely? Can a stuck/failed lifter prevent closure?

[ard]

Originally Posted by pshovest

Can't overlook this coincidence.
I believe all of the cam/valvetronic hardware has to be removed to change the valve seals. Can it be reinstalled incorrectly so cyl 1 valve(s) don't close completely? Can a stuck/failed lifter prevent closure?

Agree.

Or a valve retainer clip slipped off or wasn't properly seated....

Something in the back of my mind is telling me I read something like this before...here or BF...

[Toothbrush]

I took another look at the one exhaust (and intake) valve that I can see through the oil filler cap with my camera - the ones closest to the front of bank 1. Hard to tell anything looking at it from a strange angle though.

Would it be worth the effort to pull the valve cover off and 're-do' the two exhaust valve seals to make sure everything is seated properly? I don't mind doing that again, except for the fact I would need something to compress the valve springs since I rented the AGA tools last year.

[pshovest]

Smoke test suggests there is an exhaust valve leak. Certainly worth it to pull the valve cover and inspect, though I can't envision an improperly installed valve seal preventing a valve from closing completely. You can check that valve keepers are installed properly and that valve train gear looks identical to the other exhaust valves. Might put a straight edge across both cyl 1 exhaust valve spring retainers, they should be the same height. If they're not, then one is open/damaged. You can remove the valvetronic gear, forcing valves to close and check compression again. If it's still low you get to pull the head. Did you have any trouble re-timing the engine after valve stem seal replacement? Any piston-valve contact while turning engine over?

[Toothbrush]

Originally Posted by pshovest

Smoke test suggests there is an exhaust valve leak. Certainly worth it to pull the valve cover and inspect, though I can't envision an improperly installed valve seal preventing a valve from closing completely. You can check that valve keepers are installed properly and that valve train gear looks identical to the other exhaust valves. Might put a straight edge across both cyl 1 exhaust valve spring retainers, they should be the same height. If they're not, then one is open/damaged.

Thanks! That'll be my next course of action. Cylinder 1 was the first set of valves I changes the seals on, so it's certainly possible my lack of experience and quality of work is the issue.

Originally Posted by pshovest

You can remove the valvetronic gear, forcing valves to close and check compression again. If it's still low you get to pull the head.

This part I'm not quite clear on. Are you saying unclip the electric connection for the actuator (part # 11377548389) or unbolt it? I have uncliped it in the past to see if it affected the misfire, but have not done a compression test with it disconnected.

Originally Posted by pshovest

Did you have any trouble re-timing the engine after valve stem seal replacement? Any piston-valve contact while turning engine over?

I did the seals in the vehicle without removing the cams, so did not touch the timing.

As for piston-valve contact, I don't recall ever hearing anything other than air when hand cranking, any time I've ever done that and I can't see any obvious damage to the piston or valve. Though from what I have read I suppose the only way to be sure is a close visual inspection with the piston clean and/or measuring clearances. ?

Edit: Here are the results of the OTC injection cleaner (1 can) and CarbonClean MV6 (2 cans). Results for the top of the pistons are positive, though not as impressive as I would have guessed. The valve stems look roughly the same, however, getting a good image is very difficult at this time. I've attached comparison pics for Cylinders 1 and 2 and pointed out some differences.

Note: For Cylinder 1, I had previously soaked it overnight 3 times using Acdelco X66P Fuel Injector Upper Engine Cleaner, which is why it looks so much cleaner and you can actually see parts of that piston without contamination, thinking the Piston Rings might have been the problem (obviously not now). That product did much more to clean the top of the piston, but obviously can't do much for the valves as you just pour and soak, then remove. Although, I have had fleeting thoughts of getting the exhaust valves open and then filling the cylinder up as much as possible without getting the cleaner in the exhaust port to see if I could get at least some of the valve/s soaking.

There are some videos for other BMW owners using it for Ring related misfires with good results. Cylinder 1 looked just like the other 7 until I soaked it with X66P, in case anybody mistakes it's condition with a head gasket problem.

[pshovest]

Originally Posted by Toothbrush

.........This part I'm not quite clear on. Are you saying unclip the electric connection for the actuator (part # 11377548389) or unbolt it?............

Not the electrical part, but remove all of the mechanical valvetronic pieces, springs, levers, etc., between the camshaft and valve stem.

Originally Posted by Toothbrush

..........I did the seals in the vehicle without removing the cams, so did not touch the timing...........

OK, good. I thought camshaft removal was required for valve stem seal replacement. If you didn't touch the timing chain, then there's no way valves & pistons would make contact.