M62TU Dreaded cyl 7 misfire
G'day,
I've been reading this forum for years. About time I joined. I have an 03' X5 Sport that I'm the second owner. Purchased at 100,000km's or 60,000 miles, which ever way you want to look at it. I've since put another 60,000km (37,000 miles) on it and haven't had an issue with it until now. In saying that, I've maintained it and serviced it, as you should. I now have a misfire on the 7th cylinder. Fault code is P1355 (Misfire 7th cyl with fuel cut off) Started off with the engine light flashing once a day. Then once every few hours, now all the time. Car runs like a dogs breakfast. Immediate thought was coil. Swapped coils to see if misfire moved. No luck. New spark plugs, injector, fuel filter, valve cover gaskets (which were leaking). Misfire still persists. Cleaned MAF also. Next checked compression, which was ok. My next thought would be that the PCV diaphragm is ruptured and have ordered a new one anyway, since the car is about the age they like to go bad however I'd expect this to cause a multiple cyl misfire. I guess I'm writing this post to see if anyone has had experienced an isolated misfire due to the PCV CCV being stuffed. I live on a farm, pretty far from any mechanic that would have BMW experience and I work on engines (mainly diesel though) on a weekly basis so I have confidence I can sort it but am running out of places to look. I'll check power to the coil and injector but I'm sure they are getting power as It will run on all 8 cylinders when up in rev's, on the road but will still miss repeatedly. Will check voltage though, when I have a second person to give me a hand. Crank angle sensor? O2 sensors? I doubt they are the culprit as the misfire is isolated to cyl 7. I could be completely wrong though. Anyone who's had similar issues, please enlighten me with the outcome. Cheers! Jono. |
Did you do the basic check such as cylinders compression test? A cylinder that has less compression than the other cylinders will produce less power and the computer will interpret that cylinder as having a misfire.
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Yep, as stated, compression was fine. Has me puzzled.
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Was the compression reading in cylinder 7 the same as compression readings in the other 7 cylinders? Compression reading maybe fine if it shows compression, but if the other cylinder were higher, than the compression reading is not fine.
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So the new CCV unit arrived and I pulled the old one off to find it was pretty badly deteriorated and cruddy, as expected. I replaced it this morning but the misfire still persists. Compression was fine across the board. All around 150PSI so what's the next step? Hmm.. Mice chewing at wiring? Loose earth due to living on a bumpy dirt road?
I'll get my multimeter out and do some more investigating, me thinks. |
Leak down test is "the next step". Specific, methodical diagnoses is the key. A lost art this day and age....
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On the E34 forum when I owned an E34, a guy was having a misfire in his car. Turns out that one of the coil drivers in the DME / ECM was bad. He replaced the DME and the misfire went away. In these days of coded parts by BMW, swapping a DME is not easy. Perhaps there's a service that can test and rebuild your DME/ECM.
This guy on eBay repairs BMW DME. BMW ECM ECU PCM Engine Computer Repair Return BMW DME Repair | eBay |
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I have an 03' X5 Sport that I'm the second owner. Purchased at 100,000km's or 60,000 miles, which ever way you want to look at it. I've since put another 60,000km (37,000 miles) on it and haven't had an issue with it until now. In saying that, I've maintained it and serviced it, as you should. I now have a misfire on the 7th cylinder. Fault code is P1355 (Misfire 7th cyl with fuel cut off) Started off with the engine light flashing once a day. Then once every few hours, now all the time. Car runs like a dogs breakfast. Immediate thought was coil. Swapped coils to see if misfire moved. No luck. New spark plugs, injector, fuel filter, valve cover gaskets (which were leaking). Misfire still persists. Cleaned MAF also. Next checked compression, which was ok. My next thought would be that the PCV diaphragm is ruptured and have ordered a new one anyway, since the car is about the age they like to go bad however I'd expect this to cause a multiple cyl misfire. I guess I'm writing this post to see if anyone has had experienced an isolated misfire due to the PCV CCV being stuffed. I live on a farm, pretty far from any mechanic that would have BMW experience and I work on engines (mainly diesel though) on a weekly basis so I have confidence I can sort it but am running out of places to look. I'll check power to the coil and injector but I'm sure they are getting power as It will run on all 8 cylinders when up in rev's, on the road but will still miss repeatedly. Will check voltage though, when I have a second person to give me a hand. Crank angle sensor? O2 sensors? I doubt they are the culprit as the misfire is isolated to cyl 7. I could be completely wrong though. Anyone who's had similar issues, please enlighten me with the outcome. Cheers! |
I would verify that you have spark at the plug and an injector pulse at the injector and go from there.
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:iagree:
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I also agree a leak down test should eliminate internal causes if the plug and injector current are good. Welcome! |
Problem Solved
So I have fixed the problem. Turned out to be the usual culprits, all at once.
Having replaced the CCV (which was completely 'chooched', as Ave would say), I then double checked the electrics. I'd already replaced the injector but hadn't confirmed I had injector pulse. Multimeter confirmed I had both steady injector pulse and power to the coil. When I first replaced the leaky valve covers, I purchased a new coil as I was pretty confident the old one on cyl 7 may have fouled due to the oil in the spark plug well. When I first swapped it out, it made no difference. This time, with the new CCV unit, it worked. Misfire gone. Car runs smooth again. So in conclusion, the valve cover gaskets began to weep at the same time as the CCV deteriorated, the pool of oil stuffed the coil (and probably the plug) and until I'd fixed the vacuum leak, the misfire would not disappear. What a bastard to get that CCV out too. I'm amazed I didn't drop those little torx bolts down the back of the engine... Thanks for your suggestions. Appreciate the help. |
If you had mentioned that when you replaced the spark plug with a new spark plug that the spark plug hole was filled with oil, someone would have pointed out to you that the oil in the spark plug tube is a known source for an engine to misfire.
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When the misfire became apparent, I went ahead and ordered a new coil as I was fairly confident this would be the issue but was too busy at the time to look at it. When I finally had the spare time to change the coil, I removed the covers only to find oil in the plug wells. It was then I realised the valve cover gaskets were leaking So I replaced them, along with 8 new spark plugs, having sucked the oil out and cleaned the wells, of course. I also installed the replacement coil. After a full day's labour, the misfire still persisted on cyl 7. Now I'm sure you can appreciate my frustration as logically it should have fixed the problem. So the issue turned out to be the above, along with the CCV. For some bizarre reason, the new coil wouldn't fire (despite having power to it) until I replaced the CCV. Or perhaps it was more likely the fuel shut off to the injector.. Who knows.. Glad the X5 is out of the way. I now have to sort out the intermittent jake brake on my Signature Cummins. Out comes the multimeter again...Yay.. |
The reason for intermittent problems is to expand our ability to calmly handle frustration. Side benefit of DIY.
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I am experiencing the exact same issue here. Swapped in a spare used Bremi coil (can't confirm it was good so may try another one) spark plugs were stated to be replace by the PO but I will check those as well. Cylinder 7 is still misfiring randomly but no check engine light. I am watching the cylinder smoothness values through INPA. I ordered a new Kayser CCV and a Febi OSV and will probably do an intake reseal at the same time of the replacement...
https://www.dropbox.com/s/fs3w4xfh0u...53330.mp4?dl=0 https://uploads.tapatalk-cdn.com/202...654f82106e.jpghttps://uploads.tapatalk-cdn.com/202...40b5740a93.jpg |
Do you have to clear error codes once the DME shuts down a cylinder due to misfire?
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yes. The engine will be in limp home mode until reset. You don't need to even shut off the car if you have a wifi dobgle in the obd port.
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I have not gotten an engine light or a stored misfire code sonce clearing but I can feel it...
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sorry to hijack this. every now and again ,. maybe once every few months, my m62, runs like a dog, I can run it one time turn engine off , fire it back up and it dies on cylinder 7,, its always number 7.
its an oil fouled plug, so no spark on that, everything else tests ok, I know ive got a OK CCV on the rear of the intake , its the little vacuum pipe that connects to it that's disintegrated , I just don know why its always number 7 :) after the current lock down has passed I want to get her in for a compression test |
Replacing a couple weak coil packs and finally using some Lucas injector cleaner and no codes a year and counting.
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Replaced the PCV(Kayser) and OSV(Genuine BMW) and on INPA cylinder roughness screen, cylinder 7 still had high number and then engine still felt like it had the slight misfire. Moved the coil(bremi) and spark plug(NGK-BKR6EIX) from 7 to 6 and 6 to 7 and then watched the cylinder roughness again and it moved to cylinder 3 where 6 and 7 seemed within acceptable range now. This all happens after the X warms up. I can still hear the driver side exhaust has a slight misfire at idle. What gives?
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M62TU Dreaded cyl 7 misfire
Have you run injectors cleaner? If so the next step I would do is clean the injectors with the machine
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I do have a fuel tank vent valve error and it seems to not be functioning. Can this cause a similar issue? It only starts acting up when the engine gets warmed up...
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If failed open not a big deal. If failed closed it will crumple the tank like a beer can
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So I did an 88c tstat at the same time and upon bleeding the valley pan blew(what luck right?) So I ended up doing the valley pan, a full intake reseal including TB gasket and valve cover, vanos solenoid, UTCG gaskets and new NGK +4 plugs amd a new GRAF water pump as well. I can report back that the motor is running buttery smooth now but its hard to pinpoint the exact culprit after all that was done. The fuel tank vent system(not valve error) error is still there so this was not related to the engine roughness I was experiencing...
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Rough
Can you elaborate on what "rough running" shows you? I have seen that screen but never know how to interpret it. Thanks
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The lower the numbers the smoother it runs.
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the beast is in for a compression test tomorrow. lets hope she is good,
i dont want to think on she has some internal problems, that will be the end of the x5 |
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