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Discussion Starter #1
Hello all,

I was finally able to do a couple of WOT runs using the hidden menu. My uncorrected number is 129 and using the correction methode I am ending up with 124.

I know from searching that there are several hundred posts on this subject, my specific question is this:

Is the 124 corrected reading bad enough to cause little or lots of damamge. Is that too lean and MAFS should be replaced ASAP or do I have a couple of months. The car has 65K, is on original MAFS as far as I can tell from the receipts, as well as stock fuel filter (UNLESS it is common practice for dealer to change that during Inspection II).
 

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Hello all,

I was finally able to do a couple of WOT runs using the hidden menu. My uncorrected number is 129 and using the
correction method I am ending up with 124.

I know from searching that there are several hundred posts on this subject, my specific question is this:

Is the 124 corrected reading bad enough to cause little or lots of damamge. Is that too lean and MAFS should be
replaced ASAP or do I have a couple of months. The car has 65K, is on original MAFS as far as I can tell from the
receipts, as well as stock fuel filter (UNLESS it is common practice for dealer to change that during Inspection II).
Though your fuel flow is nothing to be concerned with, I would encourage you to replace your fuel filter and install
a fresh set of MAFS's (from Bimmerzone). Your beast will reward you handsomely with some new-found ponies.

Regards,
Alan
 

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This value doesn't tell you anything about the fuel/air ratio, it's just a raw measurement of fuel being delivered. It could be due to a lean condition, it could also be due to bad MAFs or any number of other things and the FAR could be fine. At any rate, as far as I know, the car is smart enough to pull timing if it detects an overly lean condition and you'll lose power before you do damage, unless you're so far out of whack the ECU can't compensate.
 

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Like mentioned, its not a test of A/F.

example. If you have a clogged fuel filter, your #s will be lower, and would result in a leaner than optimal A/f.

If you have clogged air filters, you would be getting lower numbers but the end result would be a richer than optimal A/f.

The computer compensates for both, so the only way to tell what the A/f is , is to to actually meter the A/F.

The test is only a measure of the combination of several systems, any one of which could result in lower numbers; however, lower numbers cannot directly be used to dagnose any individual part when only looked at in its entirety
 

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you do know that all these flow numbers and maf "tests", were cooked up by people here. these aren't tests that a dealer or probably even most indys would use. as already said this number is only a measure of fuel flow. a low number dosen't necessarily mean bad mafs, and 124 isn't that low anyway.
 

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you do know that all these flow numbers and maf "tests", were cooked up by people here. these aren't tests that a dealer or probably even most indys would use. as already said this number is only a measure of fuel flow. a low number dosen't necessarily mean bad mafs, and 124 isn't that low anyway.
After this was shown this to the shop foreman and lead tech at my local dealer about 5-6 years back, they began using it on all M5s that came in with owners complaining the car was off full song since there is never anything stored in most cases, so a quick check of WOT L/h peak flow at 7k in 2nd gear quickly determines if someone is accurate in their complaint.

To OP, my car with 57k miles now, only would return 128 or so corrected a couple of years back (~45k miles), so I replaced the MAFs and could then get ~130ish corrected. This summer I replaced the spark plugs, and immediately was hitting 138-140. I was surprised the plugs made that much of a difference since the old ones (original) didn't look bad at all.

If you car has the original plugs, I'd start by replacing those along with the fuel filter. Both of these are easy and inexpensive places to start. Don't fool with the MAFs until you've done these first imo.

Chuck
 

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For the OP, I don't think your MAF numbers are bad.

I would suggest one change at a time and after a few days for the car to adapt, do another set of WOT runs. This way you can isolate any improvements.

Fuel filter, and spark plugs should have been done on Inspection II IIRC. Those show up around 60k miles, depending on how hard the car was driven. But changing the fuel filter is no big deal and piece of mind. If you go to the trouble of pulling plugs to inspect, I would have a fresh set handy since it is just as much work to put back new plugs are used plugs!

MAF cleaning usually indicates if you have worn MAF's. A temporary improvement in WOT #'s indicates worn MAF's. Most consider MAF's a wear item; check the board here for some good pricing on replacements. Remember, you only need the sensor, not the entire housing (which is what a dealer and some vendors try to sell).

Regards,
Jerry
 

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Discussion Starter #8
I called the BMW dealer in Ft Lauderdale and to my surprise the Fuel filter is NOT listed anywhere on the invoice as being changed during Service II.
Spark plugs are 4K miles old and were changed during the Inspection II.

Is there is a way for me to check if the fuel filter was changed, may be a visual inspection, if it looks arther new etc?

As far as the numbers go, if the fuel filter is still original, I will change that first and then do the MAfs.

Thanks to the responses and what I have read from even more searching, the 124-128 number isn't too bad and since I need new ffront rotors i will not be doing much of WOT during regular driving anyways.

Thanks for the tips on MAFs, to not buy whole housing.
 

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Fuel filter is not part of the inspection II. It is an easy DIY.
 
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You might be able to tell by looking at it (I don't recall if mine had a date stamped on it when I changed it about 6 months ago). As stated, it's an easy DIY. Be sure to check your vacuum lines and fuel pressure regulator when you take the old filter off.
 

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... and make sure you install a new crush washer (copper) when you connect up the new fuel filter. It typically does not come with the replacement part so you will need to get one separately. In fact, get several. They are handy to have around.
 
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