Hellish misfire
 

Hey folks!



I am the proud owner of a faulty N62 4.4l X5, with a constant misfire on cyl 7 and I was hoping one of you could help out.


To start the initial issue was a leaky plug tube, the tube seal was leaking oil into the plug and plug 7 was coated with burnt, flaky oil, which was mitigated with a brand new (Febi) tube and valve cover gasket, the car ran fine for about a month.


To which about a month ago, I got codes for multiple misfires on cylinder 5,6,7 with injector circuit open codes. I re-seated the injector connectors which was a "fun" task, but which helped cyl 6, no more code on cylinder 6. So I just bought 2 new injectors for Cylinders 5 and 7, replaced them, and I was still getting injector open circuit, I then tested the harness and noticed that 2 pins (for cyl 5 and 7) were not making contact, cool, ordered a harness, it came, I replaced, all of the codes for injector circuit open were resolved BUT the misfire on cylinder 7 remains.

From that point, I have taken the DME out, it of course, had oxidization on some pins, so I used contact cleaner and clean the connector side and the DME side, I also opened up the DME, tested the FETs and they tested fine. But still a misfire on cylinder 7.



Now we come to today, I decided to clean the coil harness and the ground points on the valve cover for bank2, I also replaced the brand new plug with another new one (all 8 were replaced 3 months ago after the valve cover job), I also tested 4 (brand new) coils, 4 different brands, 2 Bosch from different eras, 1 Delphi and 1 OEM from BMW, no luck there.



I am losing my patience with this thing, I have never had such a persistent misfire with so little information, I have access to tools like ISTA, BMW scanner and a regular OBD scanner, none of which show any relevant codes, and all the Lambda, O2 and MAF stats meet requirements of the DME, so its not sensor related (from what I can tell).



I would also like to add that the Fuel pump has been replaced by an OE unit from FCP (All parts are from FCP and I DO NOT use after market garbage). Also the vanos solenoids have been cleaned and tested, they work fine. I also made sure to re-learn the valvetronic motors before starting the engine after the VC replacement (Using ISTA).



For some back story, I have had a e46 for 6 years now, have done all the work on it myself from regular tuneups to code for a manual swap. I have had many many issues that have taken a few days to solve but this is going into a month of not being able to figure it out.

It misfires from start, until the engine is turned off, after the regular 60 seconds (I think) the DME shuts off fuel to Cyl7. I have also attached the freeze frame that I have from OBD Fusion.


Please, anyone suggest anything that I have not thought of, after all I am an M54 knower, I do not have a lot of knowledge of the N62B44.

Try your ISTA to verify code as "P" codes are generic and sometimes not what you think.

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I don't anything about the V-8s but you need to do a compression test. Maybe faulty new injector? Strange that you have/had so many injector harness problems??

Prior I did read the codes and they revealed the same + cylinder shutdown due to the misfire and alternator code, but there is nothing wrong with the alternator... it is charging the battery just fine @ 13.6 - 13.8V. I do think it might be the comms wire to the alternator that is the issue, but that is not the cause for Cyl7 misfire (At least I do not think it is?) The battery is at a constant voltage and does not drop below the "regular" 12.7V (when powered off) and 13.6V when idling. I also did replace the alternator regulator and battery not too long ago (about 5 months now).

Cheers for the suggestions, I have decided to read the car again with ISTA just to be sure, SS is attached, along with some stats from INPA (I know it a bit better) Maybe these can give a hint to something? The Camshaft advance on bank2 is a bit high, not sure if this could be related or if its normal, seems to be out of spec by a few degrees?

That is my next test for sure! My in-law will be bring his compression tester here tomorrow and I will test it, I can say that I know the injector is firing now since I can smell the raw fuel being dumped out the exhaust. (This stops as soon as the DME shuts off Cyl7. So its not Fuel...

As for the injector harness... yeah... weird is all I will say... It might have been me though, when this first started I did put a needle connected my voltmeter to test continuity and I may have busted the pins on the harness side? Maybe? I do for sure know its on the harness connector and not the injector side that is the issue. Since I swapped the harness out, 0 issues with the injector open circuit and with INPA I can successfully now control each injector. Before swapping that harness, I could not.



A new development tonight, crank but no start... Never happened before, I was working on her earlier today, started a few times and had no issues, tried about an hour ago and she would not start at all, Had a few cylinders fire off and then it would just crank with no start. I tried 3 times and the 3rd time she started with the same cyl7 misfire... No new codes nothing new besides the no start.

Knock value up on 7 is worrisome but not necessarily a problem. Compression test will tell more. I'm not sure if it's a problem with these engines but a worn out cam lobe is something to keep in mind. Strange that 2 misfire codes and the alternator code got set at the same mileage and the adaptive headlite code 5 miles later.

I believe the knock on Cyl7 is because of the cylinder shut off? Higher knock since the piston is being dragged rather than exerting the forces from combustion. (I am not sure thought...)

As for the codes, I was testing things, so I cleared them prior to taking the photo, the headlight level sensor and alternator have been an "issue" since we got the car 3 years ago, I have the headlight sensor ready to replace when warmer weather comes and the alternator regulator was replaced but the code is still there, as I mentioned, I believe its the comms wire that connects to the back of the alternator, I will troubleshoot that in warmer weather though.



I did stumble upon a thread that mentions incorrectly seated valve retainers after a valve stem seal job causing a constant misfire. And the behaviour looks the same as what I have on Cyl7. So this compression test will probably end with not great compression... :sick:


As mentioned earlier, today I will be getting a compression tester, I am hoping to be able to do the test today when we get back.

Good evening folks!


So, I just came back from testing the compression on cylinder 7. its a whopping 0. Nothing, needle does not budge... it sounds like the exhaust valves may be open, But I do not understand how that is possible, I did nothing in the engine that would cause this all of a sudden...



Needless to say, I am lost for words and for next steps. Should I remove the valve cover to check if the valves are stuck open? Or a collapsed spring maybe?


Bare in mind, the garage is not heated and its 5F haha.



Thanks to all that have contributed this far!! Take care ya'll!

For sure take the valve cover off and have a look. I'm gon'na assume the rest of the cylinders tested good??

Ouf, sorry, forgot to mention the others, they seem within spec, lowest was 149 and highest was 165. Lowest was cylinder 4.

Fiber-optic cam could check valves.

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Any Endoscope will do? - there are tons on amazon and the like. I am not sure how to get it to turn 180 degrees to see the valves. I have never needed to use one.



Or would it need to be something like this: https://www.amazon.ca/Articulating-B...%2C114&sr=8-16



Thanks!

Most cameras come with adapters. Adapters will allow use for side, downward, or upward views. Both of my cameras have adapters.

Gotcha, thanks! I will order one in the mean time.

Some of them have a turn adjustable end also...

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Hey Folks, quick update. I took the valve cover off and I cannot see anything wrong with the intake/exhaust valves or the cam shafts or the valvetronic shaft.. I have attached a ton of photos of the Cyl7 valves rockers.



I am still waiting for the borescope, no news on that front, it should be arriving on the 3rd of Jan.



I did manually crank the engine over and throughout the whole firing cycle, there was a hissing sound (kind of sounds from the exhaust.) I do not think this is normal since Bank1 did not have the same sound.

Is it just the lighting or do you have a groove in your roller?https://uploads.tapatalk-cdn.com/202...ab92f18240.jpg

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There is a slight grove, but my nail was not catching on it. It’s fully smooth.

Thanks I just wanted to check. [emoji106]

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Oh for sure! Best to check, I could miss something. Thank you!

Do you have the adapter for your compression tester that allows you to put some compressed air to it? At TDC with compressed air, you should hear something somewhere.

Did you check valve lash? Next, put a little oil down the plug hole. Do a compression check. Does it go up? Oh, air intake should maxed out. Remove the throttle body or another intake hose. On older engines, flooring the pedal would open the throttle body. Can't do it on an electric TB. Or does BMW have a flooding clear option by flooring the pedal?

I do not, I will check whether I can cobble something together because this is a brilliant idea! Thanks!



I did not check for valve lash as I do not have feeler gauges (yet), I ordered some, they will take a while to get here... I live in the sticks so any part/tools take forever to get to me... I will see if the father in law has some to bring with tomorrow.



When you say a little bit of oil, how much are we talking? I would prefer to avoid bending the rod :P I am guessing like ~2 tablespoons would be good? For the intake, I do not have a spare TB gasket, would me removing the CCV hose be enough?


Thank you! And happy holidays all!

Actually less oil! It would only take a few drops to see if compression changes. At top dead center, another emission style test can be done. Using a vacuum cleaner. Connect the hose on the vacuum outlet. Connect the vacuum hose to the exhaust. Turn on the vacuum cleaner. Where is the air coming out?

Disconnecting a top intake CCV hose would work. Not the valve cover one.

Gotcha, thanks X5chemist, I will try the few drops of oil + compression test on Tuesday.

If it so happens to change the outcome of this method compression test what would it prove? I’m guessing piston rings being shot or maybe head gasket?

guys. if you have zero compression in cylinder 7, you are having burnt valve that is warped and not seating on the valve seat. there's no point in doing anymore checks, OP already took over valve cover and the keepers/springs seem to be undamaged and that was the only check needed. while other member's posts are coming from a good place, it's really all a waste of time after the compression was determined as zero and then checking physically valve gear from the top after removing the cylinder cover.
Replace the engine head with a good used unit, or remove and send damaged head for repairs.

Very true!

Adding more checks. If you suspect a head gasket, pressure test the cooling system.

As unfortunate as this news might be, I would prefer to stop working in a frozen garage haha.

I will still wait for the borescope to arrive and do a few mundane tests before calling it. Besides the head gasket and intake/exhaust gaskets, are there any other gaskets I should order/prepare for? Maybe valley pan gasket while I’m there?

Thank you!!! And happy holidays.

Hey guys, so the borescope finally arrived...

Well needless to say I found the issue.... :banghead:

So it also seems that I need a new block, since there is no-one around me that could possibly work on alusil cylinders and for that matter I would not trust the work. I have seen too many "rebuilds" fail.

That said, anyone know of a N62B44 engine for sale in Canada that won't cost an arm, a leg and a kidney? LOL.

Thank you to all that have submitted all of the great advice and suggestions, I really appreciate it. Happy new year to all!

I would look for a replacement engine. ;(

It might not be a contributing factor but were you using regular gas by chance?
Or maybe pissed someone off who put something in your tank ??

No, I was using shell premium since getting the car and no signs of tampering of the gas filler neck/tube so I would say no to vandalism. I use shell premium in all my beemers.

I think the issue was that the spark plug tube was leaking for a long time before we got the car. I believe the oil crud buildup on the valve is what caused this. I could be wrong though. It’s a shame she was running so good up until the misfire started.

At least when it's that bad you have less decisions to make! ;) Good thing you took EOD's advice and got the camera scope first, that saved pulling the head off.

I have a 4.8L block... but a 4.4 ... maybe just call around local wreckers and have them take out an engine for you!

Seems I have 2 decisions, buy a wrecked one from auction to swap the engine/trans or try find a motor. Yeah, makes the choices much easier lol!


I called around, no one has a bmw never mind specific ones haha! I got a few more sources I can check.

Also, you definitely called it! I mean it’s more than burnt but yeah haha. Thanks!

I have found a replacement engine, 156k km on it. I got the trans with it too since my trans is high miles and I just wanted to be safe since I will be there already.


So I see its not really possible to pull the trans + engine out with a cherry picker, I was wondering if it would be possible to pull the front clip off, which would then give me the space I need. Has anyone gone this route?


Apart from the alternator bracket and the valve covers. Any gaskets I should do while the engine is out? I would prefer not to separate the trans from the engine. But maybe it would be wise to do it and sort out that rear coolant cover?


Thanks!

the only seal you won't be able to reach with the transmission connected is the rear main seal, which you should do since it will be easy with transmission and engine out. how can you be so lazy to have a complete engine and transmission out but then not want to separate them and do the job properly

I have no idea why you have problems finding an engine. I see another parts E53 with a 4.4 engine for $1000 another one comes for sale every week in my area

Redo the coolant system. Anything you can't reach without removing major parts should be updated for preventative maintenance.

Its not laziness so much so as needing to take time off of work to do this along with getting my wife up and running again. Also I will be doing this job myself and my back has not healed since an accident last month, so I am trying my best to trim down on extra work where I can. I am just trying to simplify an already massive job.

And I just said I would prefer not to separate the 2, if its advised, I would do it without hesitation.



As for the availability, I live in the sticks in Manitoba, shipping is outrageously expensive, along with no 4.4l being available, all the junk yards I called near me (within 4-6 hours drive) did not have any BMWs, let alone specific engines. Most BMWs available here are base models anyways.





Cheers! Most of the coolant items were replaced, Rad, Expansion tank, hoses, pump, thermostat. I will be swapping over the new parts from old engine to new one with brand new gaskets.

There is a thread somewhere about pulling the engine/trans through the front. I think that's how I would do it.

Just get a parts car shipped to you. You can get one for $500-1000 and then just add transportation

Hey Folks, so the engine/trans got delivered, upon inspection, the cylinder walls are perfect and the valves are in great condition.


One question I do have, there seems to be a revised CCV system on the new engine, the cylinder 1-4 valve cover, the old engine has the CCV diaphragms built into both valve covers, however the new engine has an external one for cylinder 1-4 and the VC for 5-8 have it built in like the old engine.



Part# for the CCV repair kit: 11127547058
Part# for revised VC: 11127563474
Part# for old VC: 11127522150
Part# for external CCV: 11617563476


Now it would be simple to keep the revised VC, my only concern is that the new CCV has an electrical connector that the old engine does not. This is the only difference with the 2 engines, should I be concerned or should I just swap over the the old VC that has the built in CCV? (I am changing the VC gaskets anyways, so it does not really make too much difference efforts wise).


In my opinion, the external CCV has a connector, whether its a sensor or a solenoid, I cannot tell, but the DME on my car will not know what to do with it, maybe it will? With that in mind, I think it would be best to swap to the older VC.


Cheers!

There was an update for some CCV systems adding a heater (heated elbow on the N52) maybe that's what your electrical connection is??

That would make sense! Since it’s off the valve cover, and there are lots of “issues” with the m54 being away from the heat, which was later fixed by the built in ccv.

If that’s the case, then I’ll just swap the vc with the old one. Thank you! I was just worried it might be a solenoid of sorts that moves that diaphragm. I didn’t want to take it apart because those tabs are notorious for breaking.

There were also updates on the heaters for starting fires. I THINK the problem with that was mostly due to the connectors.