MAFS OEM or VW's?

Laidback · #1 02-25-2009, 01:16 AM

I had an interesting chat with M5m3mc (hope he chimes in here) between using the VW MAfs as oppose to using the OEM MAFS, note he have used both MAFS and have extensively research the pros and cons of both...long story short after our conversation i'll go ahead and order the OEM MAFS

...i'll let M5m3mc explain his theory and experience (this will be an interesting topic)....

m5m3mc · #2 02-25-2009, 02:09 AM

Will explain my thinking later this morning...

onerevn7 · #3 02-25-2009, 08:19 AM

looking forward to it....

m5m3mc · #4 02-25-2009, 02:18 PM

Many in the E39 M5 community are using the Bosch xxx032 MAFS in lieu of the Bosch xxx029 BMW OE MAFS because of the cost factor. (VW MAFS run generally 1/3 of the cost). I've used 3 sets of OE and 2 sets of VW to date so while I have an accumulated anecdotal basis of comparison, therein lies the crux of the matter - we can only go by what we individually feel underfoot, what we see on the dyno, what the unlocked OBC kicks out in measurements etc. - but it is specific to one's own experience and car.

My latest adventure with brand new VW MAFS, installed in a motor that predictably dynos between 353-358 RWHP on the (conservative) Dyno Dynamics dyno:

- OE BMW MAFS with 33k miles recently showed 147 l/hr in the OBC flow test.

- Installed new Bosch VW units, zeroed adaptations with the GT1 and within 100 miles experienced an SES/limp mode experience.

- Take this with a grain of salt because of the limited utility of post-cat AFR readings, but on new dyno pulls done a few weeks ago the post-adaptation VW MAFS showed AFR's of 14+ (definitely leaner than I want to see) as compared to the ≈ 12.8 range with OE MAFS and the same PC software. Although peak power was good it was not as good as I expected, and not in keeping with prior runs.

- Yesterday MFIZZLENYC in a virtually identical car on BMW MAFS saw 140+ l/hr, I saw a maximum of 111 l/hr on my VW MAFS.

- Prior to the installation of the VW MAFS I have said that my car was running as well as it ever has, and that has been borne out both on the dyno and with my butt dyno. With this latest change to VW MAFS I do not feel the same midrange throttle response anymore and on cold startup, driveability is definitely compromised until the engine warms up.

- I now have new BMW OE MAFS, will install them and report back in a few weeks...I will then have a recent basis of comparison for used BMW MAFS, new VW MAFS and new BMW OE MAFS.

My point is that my MAFS experiences mirror a growing body of anecdotal evidence that the use of VW MAFS CAN compromise the inherent performance of the S62 engine. I'll never try to save a few $$ this way again. That said, there many of those using VW MAFS that would counter with positive experiences of their own. YMMV, but within my limited means to quantify the benefits of one approach or the other, I vote for the BMW OE MAFS approach, hands down.