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Discussion Starter #1 (Edited)
I've spent days reading old posts on this subject, and in conclusion I decided I'd give it a go and try them. purchased two OEM VW/Audi sensors (Bosch 032 ending #'s) and installed them here are my results but first a little background on this car recently acquired 2002 e39 M5 51,000 miles did a thrall inspection and maintenance follows. Changed all fluids/Filters, New OEM spark plugs, AFE filters on stock Airboxes, TMS shark Injector (7000rpm) 91oct. tune, belts and hoses, mafs removed inspected / cleaned and reinstalled. Car runs great idle is good and very responsive throttle. Car has been well maintained and I doubt ever abused (know the prev. owner)....
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After above work was performed I did a L/H test and was 119-126 in 2,3,4th gears these were the original maf's (Bosch 029's) I live at 900ft elev. and ambient temps was 36deg. F<o:p></o:p>
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Next I went back to the shop and swapped to the VW/Audi sensors (they did have the extra little hole and I did NOT plug them) went back and retested L/H on same road getting essentially the same reading +/- 2 L/H. <o:p></o:p>
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Here's the twist I saw an immediate 3mpg reduction in fuel economy as recorded on the cars computer same course and driving style with the VW/Audi sensors vs. the original 50K mile oem's....? I couldn't believe my eyes I rest the computer three times and kept getting the same Mpg readings.<o:p></o:p>
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Went back to shop swapped back to the original used sensors and the lost Mpg came right back... BTW I felt no difference between the two different sensors. Engine seemed to have same power, and idle quality and throttle response was near identical.<o:p></o:p>
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Comments or explanations? <o:p></o:p>
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Because the car runs so much richer. I tried the VW mafs on my 03 and was constantly cleaning the soot off the back of the car. No ses light though... Went to new oems and the soot went down and the car pulled so much stronger.
 

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Discussion Starter #3 (Edited)
Ok so if they in fact run rich why did the L/H not change?
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The only plausible explanation I have is that the DME had not adapted to them yet, but from other posts I read people were claiming L/H increases right after changing MAf's <o:p></o:p>
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Well,most likely your old MAFs are ok then....

The L/HR reading is a combination of many factors and signals,not only the MAF signals...
 

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Comments or explanations?<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com<img src=" /><o:p></o:p>


Yeah, you put the wrong MAFs in LOL!


Placebo effect is the only reasoning behind owners reportedly seeing a difference straight away with new MAF's, unless the old ones were so bad they were throwing a code.

When i replaced mine i was extremely underwhelmed by them until the ECU adapted over say a week ish
 

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Discussion Starter #6
Thanks smartass... LOL

So you saying that I'm correct in my thinking that it takes the DME some time to adjust to MAF's? HAs anyone done L/H test back to back and seen increases right away? I'm trying to decide if I want to reinstall the VW ones or just sell um as near new and get the right ones.

For what it's worth I'm looking for real facts and experences here guys not just what you think... thanks in advance.
 

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you want a more accurate test?


Warm up the car. reset adaptations and go directly into the full-throttle MAFS test.

replace MAFS, warm up the car and reset adaptations again, do the MAFS test again.

now you've got a test that is somewhat indicative of the MAFS conditions.
 

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Well FWIW i actually swapped out my OEM MAF's for new VW ones (unbeknownst to me at the time) as they came up at a good price. I noticed no difference and LPH tests over a few weeks produced no differing numbers. I put it down at the time to my OE MAF's were still good, however, i was placated in the knowledge that i had changed them for piece of mind anyways.

I then found out that there were differences between OEM M5 MAF's and the VW ones, checked mine and found they were VW ones.

I ordered new proper Bosch 029's from Neighbour on here and replaced again. Again i noticed no difference but was once again, now 100% happy i'd put the right parts in. However, after about a week, i noticed pickup was a lot better and MAF tests showed an improvement in LPH consumption.
 

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i'd like to see all of this done while plotting voltage output of the MAFS.
 

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Discussion Starter #10
Well FWIW i actually swapped out my OEM MAF's for new VW ones (unbeknownst to me at the time) as they came up at a good price. I noticed no difference and LPH tests over a few weeks produced no differing numbers. I put it down at the time to my OE MAF's were still good, however, i was placated in the knowledge that i had changed them for piece of mind anyways.

I then found out that there were differences between OEM M5 MAF's and the VW ones, checked mine and found they were VW ones.

I ordered new proper Bosch 029's from Neighbour on here and replaced again. Again i noticed no difference but was once again, now 100% happy i'd put the right parts in. However, after about a week, i noticed pickup was a lot better and MAF tests showed an improvement in LPH consumption.

Thank you finally some revelent information I can use.....
 

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Discussion Starter #11
Anyone else with real world experience to share? At this point I do believe that it takes the DME time at adapt, I'd like to confirm with anyone else that has tried both OEM and VW and what they experienced before I spring for OEM one's and make someone a screaming good deal on two VW Maf'S ($100 for the pair used for 15 minutes)
 

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it's a Well-known fact that the dme needs time to adapt. Read up on federal emissions requirements for past and present obd2 cars.
 

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Anyone else with real world experience to share? At this point I do believe that it takes the DME time at adapt, I'd like to confirm with anyone else that has tried both OEM and VW and what they experienced before I spring for OEM one's and make someone a screaming good deal on two VW Maf'S ($100 for the pair used for 15 minutes)
My car came with fairly new VW MAFs when I bought it last year. As I went through the car replacing sensors, filters, etc. I decided I wanted OEM MAFs as well so I sprang for them. The car seems to feel a bit better (maybe a tad quicker, less hesitation on quick throttle, etc), but I never took LPH fuel measurements with the VWs in there. Maybe the car is faster because it has a few less hundred dollar bills to carry around? :dunno:

Either way, I feel better knowing the car is running the part that was specced for it, even though I never had any problems with the VW.
 

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Discussion Starter #14 (Edited)
My goal outside of necessary maintenance has been to maximize fuel economy not try to exact every last drop of performance. I'm happy to say I'm averaging 19mpg in daily driving and getting 28-29mpg with the cruse set at 70mph. If I thought the new OEM Maf's would help I'd spend the money
 

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i made the same mistake with the vw mafs. bottom line is they dont preform as well as the correct 029 mafs, save your money and get the right ones.
 
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