Question re high speed bog.

[m5luver]

I took delivery of my 2001 M5 last Wednesday.
Because of our Ottawa winters, I have only been able to drive it a few times.
So far, so good, except: Today I took it for it's first high-speed run.
Was accelerating and at 110, the engine bogged and wouldn't accelerate and I started to lose power. Downshifted and pressed the throttle but was still losing power. The CEL also came on and the car began to run not so well. Managed to get home OK and by then the CEL had gone off.
Went out a bit later around town and the car appeared to run fine. I might add that I've already had it on the highway several times up to 80 with no problems. Any ideas before I take it to the $stealer to diagnose?
Thanks in advance...Jeff

[wilsodh]

Now now Jeff.. you know the Golden Rule of M5 ownership:

"Thou Shalt Have A Peake Code Reader."



Ok, consider yourself spanked.

Now, before people jump in and start in with the usual triad (MAFs, cps, O2 sensor), I'm going to say that my hunch would be: throttle position sensor. It can come and go. When it goes bad enough, you can find yourself with a rather alarming 'engine failsafe program' message and a very unresponsive beast that will barely limp home (limp mode). Then magically it can clear up as though nothing happened. Not a big deal to replace. Let us know what the stealer finds.

Dave

[m5luver]

Thanks Dave, your response describes my situation exactly.
I will let you know what they find.
Also, I guess I missed the boat on knowing I should have a Peake Code Reader. Can you recommend which one to buy and where to buy from?
Thank you...Jeff

[wilsodh]

I got mine direct from Peake, but I think if you shop around (Performance Cafe?) you can save a few bucks.

http://www.peakeresearch.com/products.htm

Be sure to get the right one for your MY. '00's require the R5/FCX-II, and '01-03 use R5/FCZ-II-16.

Best 150 bucks you will spend on the beast!

Dave

[m5luver]

Dave, took your advice and got a Peake code reader. What a great little tool.
Also got my high speed bog issue resolved. The dealer replaced the plugs.
He advised the plugs they removed were the original plugs!
With 89,000 miles on the clock, that's a little disappointing to hear. But that's what you get when you buy a car with no history.
That's the good news. Bad news is the plugs were covered in oil due to leaking valve cover gaskets. So that's another $500.00 job. But i guess that's the cost of ownership of this vehicle. Thanks for your help...Jeff

[ard]

Hmmm. Not sure I buy that. Seems like the dealer looked at the BMW service history, saw no plugs (hey, you should have seen that when you ran the VIN prior to purchase) and figured they could replace the plugs. WHAT WERE THE CODES FROM THE CEL?

89k and original MAFs and O2 sensors?

Do the MAF test and report the numbers. I expect there may be other issues.

A

[m5luver]

Here are the codes I got before the plug change:
AE Air-fuel adaptation Cyl 1-4
AF Air-fuel adaptation Cyl 5-8
C5 Misfire Cyl #2
C6 Misfire Cyl #6
C9 Misfire Cy #9
CC Multiple Cyl misfire
E8 Evaporative emissions purge valve functional check

Here are the codes I got after the plug change:
AE as above
AF as above
E8 as above
95 Misfire with empty fuel tank?

So you're right, it looks like there is still something not right.
But yesterday I ran the car up to 140 mph before I ran out of room.
No bog or hesitation, (although I feel a flat spot in 3d gear); just a clean WOT run; whereas before it would not go past 110 without going into limp mode.
Would I be able to do this if the MAF's or O2s were faulty?
-----
OK, I just did a search on AE & AF. It appears these are the MAFs.
And E8 is the Evaporative Purge Valve (EPV).
I can get the EPV done at the same time as they do the valve cover gaskets. And I hope I can still get in on the group buy for the MAFs. At this point I won't even try to clean them, I'll just replace them.
Do you agree with this assessment?

[ard]

Originally Posted by m5luver

Here are the codes I got before the plug change:
AE Air-fuel adaptation Cyl 1-4
AF Air-fuel adaptation Cyl 5-8
C5 Misfire Cyl #2
C6 Misfire Cyl #6
C9 Misfire Cy #9
CC Multiple Cyl misfire
E8 Evaporative emissions purge valve functional check

Here are the codes I got after the plug change:
AE as above
AF as above
E8 as above
95 Misfire with empty fuel tank?

So you're right, it looks like there is still something not right.
But yesterday I ran the car up to 140 mph before I ran out of room.
No bog or hesitation, (although I feel a flat spot in 3d gear); just a clean WOT run; whereas before it would not go past 110 without going into limp mode.
Would I be able to do this if the MAF's or O2s were faulty?
-----
OK, I just did a search on AE & AF. It appears these are the MAFs.
And E8 is the Evaporative Purge Valve (EPV).
I can get the EPV done at the same time as they do the valve cover gaskets. And I hope I can still get in on the group buy for the MAFs. At this point I won't even try to clean them, I'll just replace them.
Do you agree with this assessment?

Fantastic post. Thanks. Really nice to see the evolution of the issues.

Between the MAFs the plugs and the O2 sensors, they will all impact the ability to properly control the AF mixture and completely burn the fuel. After a while, and with age, they trigger faults as their performance drifts from optimal.

I just replaced the MAFs to address the AE fault. Even with the fault the car ran fine. No limp mode, just that single fault.

Have you run the MAF functional test? I was getting 120s and they were bad. I was surprised, I thought 'bad' was going to be down to 100. It was a very noticeable improvement when I replaced them.

Don't worry about the misfire with empty fuel tank. The E8 seems like the evap purge valve- there is a current thread on this.

A

[m5luver]

Thanks ard. Once again, this board has proven to be invaluable!