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Discussion Starter #1 (Edited)
Hello all-

Ok, so here's the deal:

1. The SES light came on...but the car didn't drive differently. Pulled codes, found a misfire on cyl 1 and 3, and something for emissions.

2. Replaced a tank ventilator valve (which contributed to the emissions code), and re-set codes. That code has not come back since.

3. SES light came back on after 50 miles ...but didn't run differently. I decided to romp on it - and took it WOT to 6k. Car then went into limp mode, but not like the diesel limp (like when my VANOS solenoid went out).

4. Took it back to shop, found codes (sans emission code). So we went in, changed CPS, plugs, and cleaned MAF. The spark plug in cyl 1 was noted as fuel-fouled.

5. Took car out again. It felt underpowered still...but no SES. Ran it hard for about 3-4 mins. Then I went WOT to 6k trying to reproduce error, and bingo - SES light and moderate limp. So I know I'm not crazy for thinking it was underpowered.

6. Here's the kicker - after about 10 mins of normal driving, the SES light turns off. The car is still underpowered, but the light didn't come back until WOT test.

They now suspect fuel injector...we're putting in a VG44 fuel system cleaner. If that doesn't work, we may look at injectors....which I would think is an expensive proposition. I've already changed out VANOS solenoids on both banks awhile ago....and the symptoms don't line up with that. Any ideas?

Thanks,

Lance
 

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My car did this a couple of times on the track one weekend. If it was the same as my issue, you're getting "misfire with cylinder shutdown" according to the bmw gt1 tester. (my peak tool just gave a misfire code, but you could feel that there was one cylinder not fireing, shut off and restart cleared it). My dealer said "i don't know, we reset the adaptations and cleared the fault" which really wasn't good enough for me. I changed the plugs and put in a fresh fuel filter (have 60k, seemed reasonable). I haven't been back on the track to duplicate the conditions, but no issues yet on repeated wot drives on the street.
Mike
 

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It could be the crankshaft sensor being out of alignment, or itself or its cabling being faulty. It is rather easy to check the alignment (TIS RA 12 14 520):

1. remove the crankshaft sensor from bellhouse.
2. measure depth from seating plane to teeth on the flywheel.
3. measure distance from seating plane of sensor to front of sensor.
4. measure shims if any.
4. add or remove shims between sensor and bellhouse to get a distance of
0.55 +- 0.2 mm between front of sensor and flywheel teeth.

David
 

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DavidS said:
It could be the crankshaft sensor being out of alignment, or itself or its cabling being faulty. It is rather easy to check the alignment (TIS RA 12 14 520):

1. remove the crankshaft sensor from bellhouse.
2. measure depth from seating plane to teeth on the flywheel.
3. measure distance from seating plane of sensor to front of sensor.
4. measure shims if any.
4. add or remove shims between sensor and bellhouse to get a distance of
0.55 +- 0.2 mm between front of sensor and flywheel teeth.

David
David, when are you going to start your own M5 workshop ? :)

I recently had some powerloss problems on my car, and it turned out to be the fuelpump. They messured the fuel pressure to ~3 bars while it should be ~5+ bars. So new fuel pump on it's way. Don't think it's related to cvp911t's problem, but it might be worth it to measure the fuel pressure. Mine gave errors on lambda one of the times it lost power due to fuel loss.
 

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Well, gaining M5 knowledge is a hobby... If it can benefit fellow owners too so much the better.

I´m glad to hear they located the problem, and that it is a simple matter of fuel pressure.

Before opening the tank and replacing the fuel pump, I´d ask them to

1. Measure fuel pump current and pulse width and pulse duty-cycle of the drive current. (To rule out a fault in the pump drive electronics.)

2. Check the fuel filter and the pressure regulator, if not already done. Those are cheaper than the pump, and a lot easier to replace, and if either of those are the cause the pump can be ok, and the fuel pressure still low.

If the pump has worn out mechanically (not electrically in the motor of the pump), I would also replace the fuel filter anyway just in case it has trapped some particles from the pump.

About the replacment pump, watch it so they put the exact right brand new Bosch BMW OEM fuel pump into the tank, and not an "equivialent aftermarket product" or a refurbished pump.

Best Regs,

David
 

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cvp911t said:
4. Took it back to shop, found codes (sans emission code). So we went in, changed CPS, plugs, and cleaned MAF. The spark plug in cyl 1 was noted as fuel-fouled.
I wouldn't rule out bad MAFS. I cleaned mine per the procedures listed on this board, and the same symptoms as yours persisted except that they ocurred sporadically. Try to borrow some known good MAFS and see if you can still reproduce the problem. You have the advantage that your symptoms are consistent, mine didn't ocurr every time I went WOT.

My dealership replaced both MAFS and re-flashed the ECU and it was like a new car again.
 

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Discussion Starter #7
Thanks for the feedback all-

The shop that I had it at applied the VG44 fuel system cleanser. He says that the car performed notably better, and at WOT - it didn't throw any errors or have any "hiccups". I'm going to drive it sometime this weekend, and see for myself.

I'll keep you posted...if it's still lacking - I'm going to check the CPS alignment. I thought about the fuel pump as well...I'll let the mechanic know about that. Thanks for the feedback!

Lance
 

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cvp911t said:
Thanks for the feedback all-

The shop that I had it at applied the VG44 fuel system cleanser. He says that the car performed notably better, and at WOT - it didn't throw any errors or have any "hiccups". I'm going to drive it sometime this weekend, and see for myself.

I'll keep you posted...if it's still lacking - I'm going to check the CPS alignment. I thought about the fuel pump as well...I'll let the mechanic know about that. Thanks for the feedback!

Lance
Where do you get the VG44 fuel system cleanser?
 

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It's nice to see some really techncal knowledge on the forums. Now that the E39 is officially the "previous model", we can start to expect a higher level of technical expertise here, :thumbsup: as the reality is now that many of us can no longer simply rely on our CPO warranties. :sad2:
 

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Discussion Starter #11
OK - update on the car-

It's throwing no SES light, but there's still a hesitation on load...I'm going to drive it today to see if there is still power loss. Does anyone in the DFW area have a couple of working MAFS I can test with? If I need to shell out money for one of those, I will. I just don't want to do it unnecessarily.

Also, aren't the MAFS covered under the 8 year/100k emissions warranty?
Thanks!

Lance
 

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Discussion Starter #13
David-

Thanks so much- I'll be referencing this.

I do have another question. I talked to my SA about replacing the MAFs under the emissions warranty - he said that the cats were covered for 8 years/80k miles. However, the MAFs were not under that coverage, and expired with the 4 year 50k miles.

Is this true? If not, would someone do me a huge favor and give me the text to the emissions warranty page? My pdf manual doesn't have anything about it....and I can't really argue anything without relevant text and location.

Thanks so much!

Lance
 

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MAFs not covered by 8-year warranty

Lance,

Just looked at

http://www.epa.gov/obd/warranties.htm

The mandatory warranty covers everthing relating to emissions for the first two years, and the OBD, ECU (DME in BMW language) and the Catalytic converters for eight years.

Seems your dealer is correct, the MAFs are not covered. (I think there might be stricter rules in California. Haven´t checked.)

If you want to try to talk with BMW NA about a Goodwill repair on emissions grounds, I´d suggest to go to a emissions testing place, and have them do their worst, that is to test the car at the lowest allowed temperature after it has cooled off all day etc. If the MAfs arn´t perfect you will see a Lambda value exceeeding the allowed 1.02 (Swedish limit, but I think it is copied straight from the US regulations).

David
 

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Discussion Starter #15
David-

Again, thanks for the help. I'm going to take steps to verify that the MAFs are the culprit (per your provided link)- and if they are...then I might have to just spring for new ones....reason being I passed emissions last month on the current setup.

I'll keep you all posted....

Lance
 

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Well, the MAFs seem to be 50000 mile consumables on the M5.

But before you invest in new ones, try Louv´s cleaning method. Sometimes it takes care of the problem completely, and sometimes partly. Anyway, it gives you a possibility to verify that the MAFs indeed influence the problem you are trying to fix, if the MAF cleaning changes the symptoms.

David
 

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Discussion Starter #17 (Edited)
Update: A few hundred dollars and two new MAFs later, the car runs like a champ. She's back to full gallop. For me, cleaning them did no good - we tried every method on the board. Turns out only one of them was bad...the other works fine.

A sincere thanks to the board - you make maintenance life with an M much easier than BMW dealers intend ;)

Lance
 

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Lance,

Glad it worked out! Can I ask you a favour? Would you like to do the MAF (fuel-flow at WOT) test as described in the MAF-thread one more time with the new MAFs, and post the numbers including fuel type, engine oil temp and atmospheric data, in the MAF-thread, please?

David
 

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It is fuel-flow in l/h (litres/hour). I posted a link to the MAF thread earlier in this thread.

David
 
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