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-   -   M62TU Dreaded cyl 7 misfire (https://xoutpost.com/bmw-sav-forums/x5-e53-forum/104394-m62tu-dreaded-cyl-7-misfire.html)

Efiftythree 08-14-2016 11:40 PM

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.

upallnight 08-15-2016 07:08 AM

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.

Efiftythree 08-15-2016 08:00 AM

Yep, as stated, compression was fine. Has me puzzled.

upallnight 08-15-2016 09:58 AM

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.

Efiftythree 08-20-2016 01:06 AM

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.

CapeX5 08-20-2016 06:06 AM

Leak down test is "the next step". Specific, methodical diagnoses is the key. A lost art this day and age....

upallnight 08-20-2016 07:24 AM

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

X53Jay4.8is 08-20-2016 07:25 AM

Quote:

Originally Posted by Efiftythree (Post 1085608)
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.

Perhaps you have a dead injector

upallnight 08-20-2016 07:32 AM

Quote:

Originally Posted by X53Jay4.8is (Post 1085614)
Perhaps you have a dead injector

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!

upallnight 08-20-2016 08:10 AM

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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