BMW M5 Forum and M6 Forums banner

1 - 20 of 29 Posts

·
Registered
Joined
·
12,936 Posts
Discussion Starter #1
OK, after reading recent threads, I decided to test my MAF's although car seems to be runing fine.

I unlocked the OBC and got to test 4, which shows liters of fuel per 100kms. I understand I should see around 135-140 at WOT at or near redline.

In second gear, best I could see was high 90's. I am thinking bad MAF's.

Then I try first gear and see 150+. Based on that, no problem. I am running taller gears, but I don't think that should matter.

So, bad MAFs based on 2nd gear runs, or no problem based on 1st gear runs?

I am going in for last covered warranty service next week, so all opinions welcomed!!
Regards,
Jerry
 

·
Moderator
Joined
·
10,458 Posts
hmm odd. with headers, you should be seeing more fuel flow. WHen i ran mine, in second gear i saw 166l/ hr. I tried it again in 4th gear, just for the heck of it but ran out of road at about 6k rpm, i was near 140l/hr at that point. 90 seems low for second gear. You'd think 7k rpm WOT should be the same regardless of gear, but it does seem to be a little lower in the upper gears.
Mike
 

·
Moderator Emeritus
Joined
·
2,977 Posts
What were the temperature/barometric pressure/humidity/altitude?

Given your location and the season, it could be as simple as heat-soaking.

For best accuracy drive the car with sport on at 50 MPH or so for a while (in order to reduce engine compartment temperature), then downshift to 2nd gear and accelerate WOT between 5k RPM and rev-limiter. Then slow down to 5k RPM and repeat a few times.

David
 

·
Registered
Joined
·
5 Posts
Clean your MAF's. It took me a mere 2 hours and cost me a meagre £10 (most of which was for the torx screwdriver I didn't have) but I did it, and my car runs like new !! :M5launch: I can't believe that doing something so simple, and so cheap can make such a huge difference in performance to my car, but it did ! I highly recommend that anyone experiencing the same/similar symptoms with their car should consider cleaning their MAF's. The instructions (in previous post) were very simple and easy to follow. Thank you M5board.com ! hiha
<!-- / message -->
 

·
Registered
Joined
·
12,936 Posts
Discussion Starter #5
DavidS said:
What were the temperature/barometric pressure/humidity/altitude?

Given your location and the season, it could be as simple as heat-soaking.

For best accuracy drive the car with sport on at 50 MPH or so for a while (in order to reduce engine compartment temperature), then downshift to 2nd gear and accelerate WOT between 5k RPM and rev-limiter. Then slow down to 5k RPM and repeat a few times.

David
Thanks. Hadn't thought about heat soak, good point. I always run with sport on. I did accel from about 4k and even in second the rev limiter comes up pretty fast. It is crowded, so I have a hard time finding a stretch of road. May have to do some early morining recon runs!
Regards,
Jerry
 

·
Registered
Joined
·
12,936 Posts
Discussion Starter #6
dino_rolle said:
Clean your MAF's. It took me a mere 2 hours and cost me a meagre £10 (most of which was for the torx screwdriver I didn't have) but I did it, and my car runs like new !! :M5launch: I can't believe that doing something so simple, and so cheap can make such a huge difference in performance to my car, but it did ! I highly recommend that anyone experiencing the same/similar symptoms with their car should consider cleaning their MAF's. The instructions (in previous post) were very simple and easy to follow. Thank you M5board.com ! hiha
<!-- / message -->
Thanks. I know about MAF cleaning, but if I am under warranty and the MAFs are defective, I will just have them replaced. Other than the contradictory readings, the car drives fine, so I am just trying to determine if there is anything wrong.
Regards,
Jerry
 

·
Registered
Joined
·
376 Posts
Hi Jerry,

We have similar mods on our cars...I only get high 90s to low 100's with may car at 4900 feet altitude...and to throw more fuel on the fire, it seems that I get about 3 to 5 more liter/min fuel flow with the K&Ns as oppopsed to stock, new, paper...

Mark
 

·
Registered
Joined
·
12,936 Posts
Discussion Starter #8
drallen said:
Hi Jerry,

We have similar mods on our cars...I only get high 90s to low 100's with may car at 4900 feet altitude...and to throw more fuel on the fire, it seems that I get about 3 to 5 more liter/min fuel flow with the K&Ns as oppopsed to stock, new, paper...

Mark
Thanks for the extra data point. I tried again today, 94-96 degrees out. Car was not stuck at light, so I think I got two good runs in 2nd without much heat soak. The two runs were a couple of minutes apart. I saw 113 one time and 115 another just as I hit the rev limiter. The car pulls great though, so I am inclined to think there is nothing wrong, especially in light of pulling 150 in 1st gear, unless someone here indicates otherwise.
Regards,
Jerry
 

·
Moderator
Joined
·
10,458 Posts
gsfent said:
Thanks for the extra data point. I tried again today, 94-96 degrees out. Car was not stuck at light, so I think I got two good runs in 2nd without much heat soak. The two runs were a couple of minutes apart. I saw 113 one time and 115 another just as I hit the rev limiter. The car pulls great though, so I am inclined to think there is nothing wrong, especially in light of pulling 150 in 1st gear, unless someone here indicates otherwise.
Regards,
Jerry
Still seems low to me Jerry. I saw 166 and repeated it and got 163 with the obc saying 111F coming back from a track event entering highway 5. Had a mix of 91 and 100 octane in the tank.
Mike
 

·
Registered
Joined
·
12,936 Posts
Discussion Starter #10
mottati said:
Still seems low to me Jerry. I saw 166 and repeated it and got 163 with the obc saying 111F coming back from a track event entering highway 5. Had a mix of 91 and 100 octane in the tank.
Mike
Hmm, based on your info, maybe I should try cleaning. I know if I tell the dealer, they will have to run a "dynamic" test and probably flog the car. I have a bunch of errands set for tomorrow, maybe I can find time to pull the MAF's and give them a bath in Simple Green and alky. 160 is a far cry from 115; certainly strange 1st and 2nd gear pulls are so far apart (150 vs 115). Thanks.
Regards,
Jerry
 

·
Registered
Joined
·
12,936 Posts
Discussion Starter #11
Thanks to mottati, all is well. He pointed out I was using the wrong test. I needed to be in test 2 under program #4, which is liters per hour. I was in test 1 using liters per 100km of distance.
I only got one run, temp mid 90's, south Florida humidity, but I did see 145 in 2nd, so I think I am fine. Car certainly feels fine!!
Regards,
Jerry
 

·
Moderator Emeritus
Joined
·
2,977 Posts
mottati said:
Still seems low to me Jerry. I saw 166 and repeated it and got 163 with the obc saying 111F coming back from a track event entering highway 5. Had a mix of 91 and 100 octane in the tank.
Mike
That is a very nice number! What was the weather like, apart from 111 deg F?

What numbers do you get on normal petrol?

David
 

·
Registered
Joined
·
376 Posts
Jerry,

Now...you got me wondering...

When I get home on Sunday...I will have to re check and see if I was in the right test...

Mark
 

·
Registered
Joined
·
12,936 Posts
Discussion Starter #14
drallen said:
Jerry,

Now...you got me wondering...

When I get home on Sunday...I will have to re check and see if I was in the right test...

Mark
When you think about it, liters over distance didn't make a lot of sense, but I didn't think about looking for a second test. Just go to second test (hit left button a second time) and you will see L/H. My car idles around 2 (it does seem to move around a lot between 1.9 and 2.4) which I assume is pretty normal. Have fun doing your testing!!
Regards,
Jerry
 

·
Registered
Joined
·
138 Posts
I've been following along with all the MAF posts lately and decided it was time. I unlocked my OBC before running around today and found the following, hopefully someone can help either confirm or deny what my thoughts are.

Did several 2nd gear pulls to redline and bounced around to a max of 101 L/H I think I saw.
Did a couple 3rd gear pulls (little harder to do, never realized til I was really paying attention to all the figures how fast 3rd gear can get, wasn't expecting that). The 3rd gear pulls peaked right at redline around 125-131 L/H. I didn't do any first gear pulls, might do those tomorrow as well. From what I can see, "properly working" MAF's should register around the 140-160 range for 2nd gear and I haven't seen conclusive for 3rd gear, but I'd guess the same?? I used the MAF cleaning procedure a few months back which seemed to really help out for a while but I fear it was a temp fix apparently. I bought some contact cleaner spray and I'll be taking the MAF's out and trying that route to clean them again seeing as a $10 can is far less than $600 worth of MAF sensor'd dealer profit margin.

Can I also safely assume I should be looking for a new set soon or am I reading the data wrong?

:cheers:

Sean
 

·
Registered
Joined
·
12,936 Posts
Discussion Starter #16
SeanMD said:
I've been following along with all the MAF posts lately and decided it was time. I unlocked my OBC before running around today and found the following, hopefully someone can help either confirm or deny what my thoughts are.

Did several 2nd gear pulls to redline and bounced around to a max of 101 L/H I think I saw.
Did a couple 3rd gear pulls (little harder to do, never realized til I was really paying attention to all the figures how fast 3rd gear can get, wasn't expecting that). The 3rd gear pulls peaked right at redline around 125-131 L/H. I didn't do any first gear pulls, might do those tomorrow as well. From what I can see, "properly working" MAF's should register around the 140-160 range for 2nd gear and I haven't seen conclusive for 3rd gear, but I'd guess the same?? I used the MAF cleaning procedure a few months back which seemed to really help out for a while but I fear it was a temp fix apparently. I bought some contact cleaner spray and I'll be taking the MAF's out and trying that route to clean them again seeing as a $10 can is far less than $600 worth of MAF sensor'd dealer profit margin.

Can I also safely assume I should be looking for a new set soon or am I reading the data wrong?

:cheers:

Sean
From list discussions, your 3rd gear pull looks about right. The list wisdom is somewhere around 135 L/H. So depending on temp, humidity and altitude I would say 3rd gear looks ok. 2nd is low, try that one again. One tip I got was to make sure the car was not heat soaked (like sitting at a light before doing the run). The car should be rolling to allow flowing air to cool everything. Then run in 3rd to say 3000 rpm, downshift to second and nail it. Careful, redline will come up pretty quickly. Readings should be similar to 3rd gear pull.
With headers, higher numbers might be expected due to better airflow. mottati got around 160, I got 145 in the awful Florida heat this week, so I am pretty comfortable that the MAF's are working fine.
Regards,
Jerry
 

·
Registered
Joined
·
530 Posts
I have followed the MAF testing threads closely. I almost always go to test mode 4, test 2 when driving, just out of curiosity.

Original Test results:
Temp = 63°F
RH% = ~55%
~30.05"Hg
7300 RPM Rev Limiter [Powerchip]
AA CAI / UFM IATS Relocation / Supersprints / Racing Cats / Tubis [Not too Loud but real Sweet]
93 Octane
3.45 Diff
35K on the car.
This gave me 140 l/h max.

I put in new paper air filters:
Temp = 93°F
RH% = ~85%
Pressure~29.89"Hg
Max = 135 l/h.

1.9-2.0 l/h at idle. 0.0 when using the engine to brake.

Seem that the Oil T° runs a little hotter after the new air filters. Same thing happened when I cleaned my MAF's. (Running hotter). Anyone else experience this.

Also--When I hit the rev limiter, it shuts the engine off--then on again-- a real violent oscillation--is this norrmal? I know it is called a limiter and not a rev governor....
 

·
Registered
Joined
·
138 Posts
gsfent said:
From list discussions, your 3rd gear pull looks about right. The list wisdom is somewhere around 135 L/H. So depending on temp, humidity and altitude I would say 3rd gear looks ok. 2nd is low, try that one again. One tip I got was to make sure the car was not heat soaked (like sitting at a light before doing the run). The car should be rolling to allow flowing air to cool everything. Then run in 3rd to say 3000 rpm, downshift to second and nail it. Careful, redline will come up pretty quickly. Readings should be similar to 3rd gear pull.
With headers, higher numbers might be expected due to better airflow. mottati got around 160, I got 145 in the awful Florida heat this week, so I am pretty comfortable that the MAF's are working fine.
Regards,
Jerry
I tried again and did several 1st gear and 2nd gear pulls. Results:

1st gear pulls I got 102 L/H max

2nd gear pulls I got 112 L/H max

Ideas?

Oh, and also, this today after I cleaned them both again.

AA CAI, exhaust, straight pipes are all that are done to improve air flow.

I'm thinking I'll be ordering a set of those bosch sensors tonight or tomorrow.

Sean
 

·
Registered
Joined
·
12,936 Posts
Discussion Starter #19
SeanMD said:
I tried again and did several 1st gear and 2nd gear pulls. Results:

1st gear pulls I got 102 L/H max

2nd gear pulls I got 112 L/H max

Ideas?



I'm thinking I'll be ordering a set of those bosch sensors tonight or tomorrow.

Sean
Those numbers do look low. Is the car throwing any codes? Do you have a paper air filter or an oil bathed filter?? If the later, that will normally cause problems unless you are very careful with how you oil them.
To be safe, I would probably just order the sensor inserts from Continental, about $150 each. It seems that sooner or later most cars will need one.
Regards,
Jerry
 

·
Registered
Joined
·
138 Posts
gsfent said:
Those numbers do look low. Is the car throwing any codes? Do you have a paper air filter or an oil bathed filter?? If the later, that will normally cause problems unless you are very careful with how you oil them.
To be safe, I would probably just order the sensor inserts from Continental, about $150 each. It seems that sooner or later most cars will need one.
Regards,
Jerry
I have the paper filters as I don't want to mess with the oil fouling them any quicker than need be over little to no benefit. I am though curious as to how much performance I've actually been missing, I'm a bit excited to find out what I've been missing now!:1:Thanks for the help Jerry!

:cheers:

Sean
 
1 - 20 of 29 Posts
Top