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Discussion Starter · #1 ·
Could your driving style cause codes??? <hr style="color: rgb(255, 255, 255); background-color: rgb(255, 255, 255);" size="1"> Returned from 500km highway trip today and found new Peake Codes:

AA - "secondary air system flow too low"
AE - "air fuel adaption cyl # 1-4
AF - "air fuel adaption cyl# 5-8

after search and read on the board I realised I had:

1/ done some lugging below 2000rpm up hills in top gear with cruise control on,
2/ ran 30-40 km with fuel light on

as well, it was hot and humid, on- board computer showing 34deg C outside.

Could these conditions cause these codes??

(Have 4 new CPS, new air filters,fuel filter in last 4 weeks. )
 

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The driving style probably didn't help, but it's hard to tell whether it is the cause. Reset the codes, drive it a little more spirited, and see if they come back. If so, we can start on diagnoses.
 

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Is your ///M a 2000? IIRC the secondary air system code was the dreaded carbon build-up issue. [CBU]. I could be incorrect.

I believe the AE and AF codes are typical of MAFs, what's the mileage on the ///M and when [if] were they last replaced? You may want to do the MAF test or just pull them and clean them off with MAF cleaner or brake cleaner.
 

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Discussion Starter · #4 ·
hi guys

thanks for replies

1/2000 M5 (54,000mi) 87,000km, only had it 2 months, cant see Mafs on service records, so i will assume they are old. I did try new VW mafs a while back, but they seemed the same as the old ones so i put them back.

cleared codes yest, no new ones, except "8F ebox fan "which is always there,(have one on order)
but TODAY
wouldnt start (hot) just kept stalling, took 3-4 goes to get going, and threw "AE: air fuel adaption cyl 1-4"

could this mean mafs?
 

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My guess is yes. I'd order some new ones from bimmerzone. there's a thread on the main page about MAFs with a link to bimmerzone's MAFs. You order the pair of sensors and simply change the sensors from the housing. You don't even have to pull the housing off the swap out the sensors.

You can do the MAF test, but with that mileage/age on the MAFs you are way overdue anyway. Replace them and feel good about it. A quick cheap way to see is just clean them off with brake cleaner. Should work for a bit. Pull the sensor housings off and use a pair of vice grips to turn the security hex screws [if you don't have a set of security hex wrenches] to pull the sensors and clean them off. Just be sure to install them back the right way. Arrow on the sensor points to air flow.

With a early 2000 ///M, i believe that the 2000 MY was more prone to the CBU than any other year. So you likely have it. Best way to handle it? Spend $500 on the powerchips group buy ["what powerchips is up to"] and have them shut off the CBU error code alog with the new ECU flash. *And* get a faster, smoother ///M. CBU doesn't affect performance anyway. It's just a PITA SES light.
 
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hi guys

thanks for replies

1/2000 M5 (54,000mi) 87,000km, only had it 2 months, cant see Mafs on service records, so i will assume they are old. I did try new VW mafs a while back, but they seemed the same as the old ones so i put them back.

cleared codes yest, no new ones, except "8F ebox fan "which is always there,(have one on order)
but TODAY
wouldnt start (hot) just kept stalling, took 3-4 goes to get going, and threw "AE: air fuel adaption cyl 1-4"

could this mean mafs?
With it not wanting to start, I would wonder about fuel pressure. Has the fuel filter been changed? That's an easy DIY and something that should be done anyway.
 
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Discussion Starter · #8 ·
thanks ard mike.s and gheradini

hot -start prob getting worse -

only code now is "8f ebox fan "

takes 3 starts and throttle pumping to get running. all is ok then ---cold start good, and warm start mostly ok.

got some new VW mafs, if i try them and it fixes hot start, that would mean mafs the issue for sure?

if no better, then on to air leaks next.

thanks again guys
 

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Discussion Starter · #9 ·
free at last (code) free at last!

got my new ebox fan in today and for the first time i have been code free! No more 8F code (ebox fan) every time.

Was also getting AE (air fuel adaption bank #1) now and then after a big rev, too wet today to get more than DSC light - he he
 

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If you unplug your MAFS and your starting problem dissapears then its MAFS I suppose.

I would start preparing for a new fuel pump, if its been 70K miles on it, if your starting/stalling problems return.

Also look at intake air leaks and possibly leaking o2 sensor bungs, if your fuel adaptation codes return.

Good Luck
 
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Discussion Starter · #11 ·
update

Could your driving style cause codes??? <hr style="color: rgb(255, 255, 255); background-color: rgb(255, 255, 255);" size="1"> Returned from 500km highway trip today and found new Peake Codes:

AA - "secondary air system flow too low"
AE - "air fuel adaption cyl # 1-4
AF - "air fuel adaption cyl# 5-8

after search and read on the board I realised I had:

1/ done some lugging below 2000rpm up hills in top gear with cruise control on,
2/ ran 30-40 km with fuel light on

as well, it was hot and humid, on- board computer showing 34deg C outside.

Could these conditions cause these codes??

(Have 4 new CPS, new air filters,fuel filter in last 4 weeks. )

update

changed pre -cat o2 sensors, 2 weeks ago,and haven't had "AE " "AF" air fuel adaption codes since

"AA" secondary air system flow too low still appears every week.
 

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Discussion Starter · #12 ·
AA AE AF returned

update

changed pre -cat o2 sensors, 2 weeks ago,and haven't had "AE " "AF" air fuel adaption codes since

"AA" secondary air system flow too low still appears every week.

update on this: AA sec airflow too low -- this hangs around all the time - not too concerned as its well known issue CBU

But AA AE "air/fuel adaption " L and R banks has returned.

car runs fine, did new plugs, and found crushed earth wire to 2 coils on R bank, fixed with tape.

Fixed my pixcels last weekend and can now do Maf test:

getting 145- 150 l/hr corrected in 3rd gear before cutout.

Surely the Maf s are ok?
 
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