Verification of MAF check procedure and coolant temperature question. - The Unofficial BMW M5 Messageboard (m5board.com)

vabchbmw · 17th April 2008, 02:04

2001 M5, 45750 miles; original MAFS.

Reading through the FAQ, I set up the display under the odometer on Test #4 after I unlocked the tests via option #19. I selected the second option under test #4 xx.x L/H.

I started the car and drove the 40 minutes through traffic to a road by my house. The car was sufficiently warmed up (i.e. oil and coolant at "normal to me" readings).

I "put the pedal to the metal" and bounced the car off of the rev limiter on three separate acceleration runs in second gear.

I saw 100.x, 101.x, and 100.x L/H. WTF! Isn't the "correct" reading around 140 L/H (70F today, about 20 feet above sea level; who knows about the barometric pressure).

Could this result match up with my butt dyno telling me that the car isn't accelerating as strongly as possible?
Would this have anything to do with slight hesitation when cold

I also verified coolant temperature and it peaked at 81C in traffic, but cooled to 75C when I was cruising at 50 mph after about 2 minutes; then went back to about 78C sitting in traffic. Is this normal? After the car is warmed up, in non agressive style driving; shouldn't the variation be less?

Does this small of a temperature change deal with carbon deposits in the tail pipes if the car is running rich.

I do find it hard to believe that this small of a variation has anything to do with it. Maybe I am being paranoid.

MarkQC · 17th April 2008, 07:49

....on the L/H test it sounds like you did it right - and need new MAFS, did you try cleaning them?

If you clean them and it changes, they may work better for awhile, while you wait for new ones...

not sure on the temps, haven't tried that myself...

Stu @ M Developments · 17th April 2008, 16:28

Mine reads 147 in 2nd gear every time. I would concur with mark.

gsfent · 17th April 2008, 16:34

I get at the lower end of the scale, 120's before bigger MAF housings. As suggested above, clean them, I bet you see an immediate improvement. New MAF's are called, check recent threads for best pricing, under $200.

I don't think your temps are bad, tstat -might- be starting to stick open slightly, but I would leave it alone for now. A couple of degrees variance seems pretty normal to me.
Regards,
Jerry

vabchbmw · 17th April 2008, 17:31

Thank you for the responses.

I will try the CRC MAF cleaner from autozone or so and see if there is an imporvement, and start my search for new MAFs. I have read the numerous threads describing the temporary results obtained from cleaning. At least it will tell me if the MAFs are shot, which based on my numbers seems to be pretty clear. I cannot imagine what this car will run like with new MAFS.

I am also wary of VW MAFs. I read the thread with the poll that showed over a hundred good results with less than 20 ? bad results. I know to get the BOSCH ones made in Germany and not in China. I saw the post by Mactig (ironic that he is in my area and I think works near me) that showed how to change them, including on where to get the 5 sided? torx bit. 20 min job?

Beastpower has MAFs; aren't they just prepackaged VW MAFS with a mark-up?

Do I have to cover the hole in the VW MAFs with a thin layer of RTV?

The VW MAFs should be plug and play?

MarkQC · 17th April 2008, 18:48

I don't block the holes....

ONLY use Bosch part number MAFS, -029 is OEM, -032 is the VW, and the VW part number I think is VAG 06A906461A which includes the MAF and tube together...

You don't really need the torx bit, some have used a vise grip plyers as the screw is not that tight...

Have no idea about beastpower, look for threads doing a MAFS group buy, or low cost in search...

Plug and play with the correct ones as mentioned.

I think my last pair I purchased from pelicanparts

gsfent · 17th April 2008, 20:19

Quote:

Originally Posted by vabchbmw

I cannot imagine what this car will run like with new MAFS.

Yeah, if it doesn't bring a smile to your face, go get a Prius!

Quote:

I saw the post by Mactig (ironic that he is in my area and I think works near me) that showed how to change them, including on where to get the 5 sided? torx bit. 20 min job?

20 minutes? Well, I guess if you are a heavy drinker while working!

First time, it might take you that long, but it is really a 10 minute job at best. A couple of screws to remove, one electrical connector to unplug and then swap each MAF and reinstall. It may take the car 50 miles or so to recalibrate itself to the new MAF's so don't worry if it is not perfect upon startup.
Regards,
Jerry

E55AMG2 · 17th April 2008, 21:33

Quote:

Originally Posted by gsfent

Yeah, if it doesn't bring a smile to your face, go get a Prius!

20 minutes? Well, I guess if you are a heavy drinker while working!

First time, it might take you that long, but it is really a 10 minute job at best. A couple of screws to remove, one electrical connector to unplug and then swap each MAF and reinstall. It may take the car 50 miles or so to recalibrate itself to the new MAF's so don't worry if it is not perfect upon startup.
Regards,
Jerry

it's 5 min tops....including shotgunning a beer