540i P1346 and P1347 cyl 3 misfire after timing chain guides + vanos

[joekitch]

Solution update (2/8/18):
All these issues were caused by both of the cylinder 3 exhaust valves being bent, most likely caused by accidentally swapping the cam lock blocks during the timing procedure (A is exhaust, E is intake), this tiny discrepancy puts the cylinder 3 exhaust valves in danger because they're fully open when cylinder 1 is at TDC. The bend probably happened while rotating the engine by hand during the timing process, when you turn the engine a few times then re-verify timing. Normally it would be more obvious when excessive resistance was encountered but because i left all the spark plugs in and was fighting against compression, i didn't notice the extra force that would bend the valves.

LESSONS LEARNED: always remove or at least un-thread ALL spark plugs when doing timing, make sure you remember A stands for EXHAUST in german, and E stands for INTAKE, and if you encounter ANY excess resistance when rotating the engine. STOP and re-verify EVERYTHING




also note: i did the valley pan gasket as part of this whole procedure including replacing the intake manifold gaskets
damnnit
i thought i had given myself the christmas gift of my car running again, and it was granted, sort of..
it fired right up and aside from some audible chain whizzing noise as it gets used to its new guides (and new chain), a very very obvious misfire just by the feel of the cabin shaking.
checked obd2 codes, P1346, "Misfire During Start Cylinder 3"
so naturally i swapped ignition coil bank 1 with bank 3, same code (After clearing it of course)
THEN i swapped the spark plugs and p1346 went away but in its place came a PENDING fault p1347: "Misfire Cylinder 3 With Fuel Cut-off"
and of course thevery lumpy idle hasn't changed at all


-the coils and coil boots look fine, visually
-the plugs when i removed them looked pretty much the same between cyl 1 and 3

i then swapped fuel injector 1 and 3 just in case it was a fuel injector issue....but no luck, p1347 came back

so what should i do now? compression test? is there some common thing that can happen during a vanos and tcg procedure that can cause stuff like this?
i also used a borescope to check the condition of the valves in cyl 3 for damage and they LOOK fine
171225_115721.jpg


so, here's the story so far:
Some things i've tried already:
->swapping ignition coils 1 to 3, didn't work
->swapping spark plugs 1 to 3, didn't work
->swapping fuel injectors 1 to 3, didn't work
->checking electrical behavior of the fuel injector and ignition coil connections using a volt meter with the engine running. the ignition coil was getting 13v as per normal as well as signal pulses down the middle pin. the fuel injector connector was getting 19-25 milivolts which is what the other fuel injectors were getting too, which i found by poking the probes into the wire box and onto the metal crimps for the fuel injector connectors from the back.
->swapping all the ignition coils between bank 1 and bank 2, didn't work
->borescoped in the fuel injector port to look for valve damage, didn't see any
->sprayed some carb cleaner around the VCGs and the intake manifold gaskets around cyl 3. no change in idle speed
->compression testing all cylinders, found the cyl 3 has ZERO compression, the others are fine at around 180-190psi
->borescoping cylinder 3 found some wetness inside the cylinder that wasn't present in the others, maybe fuel?
->borescoping under the intake manifold, intake manifold gasket around cyl looks fine
->poured a cap full of oil into cyl 3 and did a compression test again, STILL zero
->turned the engine by hand while watching the intake valves on cyl 3 with the borescope through the fuel injector port, they seem to be moving normally BUT one of the intake valves had notably more gunk around its perimeter than the other valve..
->pulled the valve cover and oil rails, watched the cam lobes and lifters on cyl 3 while rotating the engine to look for broken lifter springs, but everything seems to be in order


Things i have not tried yet:

-use a borescope with a 90 degree mirror attachment to watch the exhaust valve fitment while turning the engine
-doing a piston soak with ACdelco as well as a rislone engine oil application

[dannyzabolotny]

Before you resort to drastic measures, double check all the obvious stuff. Are all of the injectors plugged in properly?

I recently did an intake manifold re-seal on a 2001 740il and when it was done the car was misfiring on one cylinder. After seeing a misfire code with my code reader, I found that the injector electrical connector wasn't fully plugged in, despite appearing to be properly connected. After plugging it in firmly, the misfire resolved itself immediately.

[JimLev]

An injector not connected properly seems to be a pretty common problem over the last few years.
Did you note if all of the metal clips were seated properly on both sides. Pretty hard to see.
Push done on the #3 connector.

[joekitch]

i've already removed and re-seated the injector and coil connectors twice by now after swapping coils as well as pulling the fuel rail off, everything is connected well as far as i can tell
i haven't yet inspected the actual connector, maybe it got damaged in the tcg operation somehow? the connector on the injector looks alright

IMG_20171225_123755.jpg

[JimLev]

Ohm the injector coil.

[joekitch]

err, the ignition coil? again, i already swapped the cyl 1 and 3 coils with no effect, misfire stayed on cyl 3
do you mean ohm the fuel injector? i did not know that was a thing, and again i swapped the injectors for cyl 1 and 3 as well, and the misfire was STILL on cyl 3

[JimLev]

The injector has a coil in it, should read about 14 ohms if it is good.

[joekitch]

The injector has a coil in it, should read about 14 ohms if it is good.

i'll give that a shot, but i'm also going to inspect all the wiring going to cyl 3 in case something got jostled loose inside the electrical box or something, or one of the connectors is fouled
but i don't see why checking injector ohms would be beneficial now if swapping injectors didn't cause the misfire to move

[JimLev]

The first time you had mention this problem you had not swapped injectors. I was just following up on the suggestion that might help others.

[joekitch]

oh right sorry, i updated the post a bit when i made the thread to mention what new things i did but that might have been hard to see, i'll put that step in bold

[Mach540]

Maybe hook up a little light bulb to the injector wires for #3. Easy check if it's getting electrons.

[joekitch]

a volt meter is more readily available and has alligator clips
although sticking clips into the injector plug while the other three injectors on that bank are still plugged in is going to be...tricky...

[JimLev]

Take to cover off the wire box to clip onto the injector wires there.
Use needles or common pins to pierce the insulation.

[joekitch]

so i popped off the wire box cover, and of course several of the clips broke because ancient bmw plastic.
Started the engine, put volt meter leads on the wires going into the fuel injector connectors and read between 19 and 25 milivolts, it fluctuated. i then read the connectors of another injector and it had the same behavior of fluctuating between 19 and 25 milivolts.
so i popped off the ignition coil connector for cyl 3 and checked that, 12v between the outer leads and the inner lead is presumably signal, seems to be sending the right signals.

One sneaking suspicion i've had is that, because the valve covers were powder coated, what's the chance the posts for cyl 3 are covered enough that the nuts don't make good contact and thus whatever coil is on cyl 3 can't get a good ground? is that a thing that can happen or does the grounding not even work that way for ignition coils?


edit: one other thing i'll try tomorrow is totally swapping all coils across both banks, since i have heard that one coil misbehaving can look like adjacent cylinders misfiring and mask the problem

[Mach540]

Shouldn't be a "valve cover" grounding issue, since the valve covers are completely electrically isolated anyways.... VCG and rubber mounted washers on the mount screws.
But isn't there a ground wire from one of the coils to the block? Hmm, maybe it is what you think. Can't hurt to put some emery cloth to it.

I'm pretty sure both primary and secondary coils are grounded internally to the brown ground wire in the connector.

[joekitch]

There are the two ground straps which are supposed to be placed ABOVE the coil but below the nut on the middlemost post on each bank, the idea is to pass the ground from the orange wire on the coil harness down to the block of the engine through the stainless steel woven strap, since as you said the valve cover is electrically isolated

540i coil ground straps.jpg



they are placed correctly on mine, although for shiggles i might just relocate the straps to one of the posts on cylinder 3's coil. since the normal position is one of the cylinder 2 posts

[joekitch]

well, just totally swapped all the coils between both banks, coil 8 to cyl 1 and 7 to 2 etc
absolutely no difference in behavior.
although i noticed that after clearing the code then starting the car back up, the code takes a few minutes to actually come back and i need to rev the engine for the SES light to start blinking and throw the "pending" code. Not sure if that distinction is significant at all.

i'm buying a decent compression tester now off amazon, autozone and advance auto don't loan them out and i wouldn't trust one coming from them anyway

if compression comes back all roses i'll be officially flumuxed'ly stumped and i'll have to give it to an indie to diagnose further
if it comes back with significant compression loss in cyl i'm completely hosed since i wouldn't know where to start on an engine rebuild or valve replacement

[Mach540]

Wellllllll........... I'm laughing as I bring this up.......... but it might be the dreaded "Bore Wash after TCG" issue that has appeared occasionally. There was a thread a while back where GG and I went a few rounds over it.
Quick way to check. Pour a capful of oil into the cylinder, turn the engine over a few times, reinstall plug and see what happens......... Nothing to lose.

[edit] Or better yet, dump a fair amount of oil in the cylinder to completely cover the top of the piston, so the rings get completely soaked in oil. Then suck out everything you can before turning over to minimize the mess.........

[joekitch]

just sprayed some carb cleaner all around the VCGs and around the intake manifold gaskets near cyl 3 with no change, meaning probably not a vacuum leak.

i'll do that oil rings check tomorrow i suppose. but if that's what's happening it looks like i'll need to pull pistons in the dead cold of winter right?
this royally googly stinks

edit: although i just remembered i did run the engine without the fuel pump for about 15 seconds total before first starting after tcg, precisely to distribute oil evenly

[Mach540]

it looks like i'll need to pull pistons in the dead cold of winter right?
this royally f***ing sucks (Did you not see JimLevs edit to your previous post?)

No, I think a good Risolone(?) treatment cures it.

[joekitch]

good gracious i sure hope it ends up being that easy
although if some oil in the piston doesn't cure the misfire either i'm going to be really REALLY confused

[joekitch]

HAH, well there's yer problem


IMG_20171228_181917.jpg


the other cylinders were all around 180-190psi on both banks, but cyl 3 showed a nice fat zero.
I did another test after adding a capful of oil, but, same result of zero psi


before i did the second compression test though, i did some borescoping.
checked the intake manifold gaskets around cyl 3&4 under the manifold, they look fine

171228_174755.jpg

also looked into cylinder 3 itself and i noticed....it seems quite a bit more damp than the other cylinders (again, this was before adding the cap of oil)


171228_175242.jpg171228_175250.jpg


is this indicative of the actual problem, or just something like unburnt fuel that's been hanging out in there for a while? since it seems this cylinder never fires even during startup.

Based on all this, it seems a lot like a stuck valve issue, any suggestions on specific things i can do to diagnose and how i can fix it?

[StRaNgEdAyS]

Try rotating the engine using the borescope to watch the valve movement?

Sent from my G8141 using Tapatalk

[joekitch]

Well, i tried to turn my borescope 180 while still letting it get into the spark plug hole...no dice, with the cord folded over it's too thick to fit in the hole, so i have no way currently of watching the exhaust valves inside the cylinder, darn


currently putting together an imgur album of moving the intake valves on cyl 3 while turning the engine by hand but imgur is being a pest, for now, have one image showing some obvious gunk around one of the intake valves.
this is with the valve fully open by the way

171229_152708.jpg


and here it is fully closed, ewww


171229_152723.jpg



i did watch both the intake valves move up and down simultaneously while turning the engine, so it's not a stuck intake valve..


i made a 60 second video showing the cams rotating by hand with the valve cover and oil rails off, everything looks fine (lifters moving fine, not getting stuck or jerking) so PROBABLY no broken valve springs




for comparison's sake here are both the valve on cyl 3, sorry they're so dark but the LEDs on this borescope cam are pretty damn lousy

171229_152226.jpg



i'm pretty sick of this usb borescope, so i just dropped $40 on what seems like a much better one, which will arrive sunday...
man i hope i don't have a bent exhaust valve...

[JimLev]

Turn the engine so all 4 of the #3 valves are closed. Then connect some air pressure to the sparkplug hole.
If you hear it blowing out of the throttle body (intake tube disconnected and butterfly open) then you have a problem with the intake valves. As you know you can see them with the manifold off the engine.
If the exhaust valves are borked (GG term) the air will be blowing out the exhaust.
Good luck.