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Discussion Starter #1
Well, it turns out that I have been pulling my MAFs numbers incorrectly.

So far, I have been using 2nd gear to pull my MAF numbers, which are always 128-129 (Corrected)

Today I had an oppertunity to use the highway and used 3rd gear to pull Maf numbers, sadly the highest I saw was 89.
This cannot be right, correct?

Either I am doing something wrong or there is something wrong with the car. How can there be such a big drop in the number from 2nd to 3rd gear?

Does everyone report and test the MAf in 3rd gear?

Please advise
 

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Well, it turns out that I have been pulling my MAFs numbers incorrectly.

So far, I have been using 2nd gear to pull my MAF numbers, which are always 128-129 (Corrected)

Today I had an oppertunity to use the highway and used 3rd gear to pull Maf numbers, sadly the highest I saw was 89.
This cannot be right, correct?

Either I am doing something wrong or there is something wrong with the car. How can there be such a big drop in the number from 2nd to 3rd gear?

Does everyone report and test the MAf in 3rd gear?

Please advise
You are using test #4, option 2??
Regards,
Jerry
 

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Discussion Starter #3
You are using test #4, option 2??
Regards,
Jerry
I am testing test #4..am not aware of an option 2.

Can you educate me?
 

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I am testing test #4..am not aware of an option 2.

Can you educate me?
There are two options within test #4... the first, which you enter when you select test 4, measures miles per 100 Liters. The second option, which you select by pressing the OTHER button once you are in test 4, is Liters per hr.

Retest, report back.

The test, when in the correct mode, will always be lower in 2nd gear....
 

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Discussion Starter #5
There are two options within test #4... the first, which you enter when you select test 4, measures miles per 100 Liters. The second option, which you select by pressing the OTHER button once you are in test 4, is Liters per hr.

Retest, report back.

The test, when in the correct mode, will always be lower in 2nd gear....

Thank you for clearing that up.

i am going out to test duiring lunch break (its bothering me) and will report back soon
 

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Discussion Starter #6
Is this the correct "Menu":

 

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Yes, now press the left button to select the 2nd mode of option 4. The display will read L/hr. That is what you want to view.
 
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Well, it turns out that I have been pulling my MAFs numbers incorrectly.

So far, I have been using 2nd gear to pull my MAF numbers, which are always 128-129 (Corrected)

Today I had an oppertunity to use the highway and used 3rd gear to pull Maf numbers, sadly the highest I saw was 89.
This cannot be right, correct?

Either I am doing something wrong or there is something wrong with the car. How can there be such a big drop in the number from 2nd to 3rd gear?

Does everyone report and test the MAf in 3rd gear?

Please advise

FWIW that's not a MAF test.. what you need is to do is look at additive and mulitplicative adaptive values. What you're looking at is raw fuel useage based on injector cycles. I know I'm beating a dead horse... I'll stop for now.
 

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Discussion Starter #9
FWIW that's not a MAF test.. what you need is to do is look at additive and mulitplicative adaptive values. What you're looking at is raw fuel useage based on injector cycles. I know I'm beating a dead horse... I'll stop for now.

You are right and the number I reported (129) was the "corrected" number. But it turns out I have been using the incorrect original/raw number.

Thank you for the correction
 

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Discussion Starter #10
Ok, so after 3 WOT runs in 3rd gear I an unhappy to report that I could only do a 119 (Raw).

When I correct the 199 for 64 deg weather, 30.13 Barometric pressure and 574 feet of elevation, I get the same 119.

So I guess I most def need new MAfs since the car has 67K miles on original MAFs and has new fuel filter and no SES light or any other errors.
 

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IIRC, the explanation given of this test in the original long thread was that at WOT, the DME ignores the O2 sensors and resorts to look-up tables and injects fuel based on air flow into the engine. So if you are consuming fuel at 140 l/hr (corrected) when you hit the limiter, this proves the MAF's are reading the correct WOT airflow. Seems reasonable. Until I saw another post that pointed out that factors other than bad MAF's can cause a low air flow reading at WOT. The simplest would be dirty air filters. Another may be bad CPS's causing less than optimum cam timing.
If the poster is correct, the MAF test should only be used for diagnosing bad MAF's when everything else that affects air flow on the engine is working! Perhaps that is why some people don't see an improvement with new MAF's - they have another problem causing low air flow at WOT.
 

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I believe the MAF sensors also have a barometric sensor in them as well and the MAF senors can fail in different ways.

There are also factors that may "color" the MAF reading results as well. Vanos not working correctly (Cam sensors, VANOS soleniods), some sort of fuel delivery problem MAY? "color" the results as well. Not sure what happens if you have 1 bad MAF sensor and 1 good sensor, assume the figures will be lower than expected, however, not sure how you could determine which one is "bad". This is probably why most folks usually replace them in pairs?

I think the only way to really verify the MAF results is swapping in a known good pair and/or swapping MAF's out with a buddies car to see what results are.

Guess you could somehow use a vacuum cleaner to at least draw air though a MAF, see if you can get any reading on the OBC, then connect the other MAF and see how the raw readings compare??
 

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Ok, so after 3 WOT runs in 3rd gear I an unhappy to report that I could only do a 119 (Raw).

When I correct the 199 for 64 deg weather, 30.13 Barometric pressure and 574 feet of elevation, I get the same 119.

So I guess I most def need new MAfs since the car has 67K miles on original MAFs and has new fuel filter and no SES light or any other errors.
HI:
I am in the same story...so did you change your MAFS lately and it get emproved or what happened.. please share us your problem

Thank you
 
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