Mass Airflow sensor conversion?

E28 technical advice asked and given! Troubleshooting, modifications and more.
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smackmybutter535i
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Post by smackmybutter535i »

I heard somwere that I can change my Airflow meter over to a MAF sensor for some good horsepower. Are they full of it? if not how would I go about doing this and without messing anything up?
rs4pro3
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Post by rs4pro3 »

Yep it can be done 15hp seems like an average power gain I hear of. Most recent GrassRoots motorsports has a nice article on adding a MAF to a S38 engine.
Shawn D.
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Post by Shawn D. »

Well, smackmybutter535i, do you really mean what you say in your signature: "I'm a newbie, help me out on what to do next for the best bang for a buck"? If so, a MAF is not the way to go. $$/performance, it's down on the list. First would be a different diff ratio (i.e. a 3.46 or 3.73), second would be a Conforti or D'Sylva chip, and third would be a lightened flywheel (if your car is a 5-speed). Unless you're adept at wiring and tuning, a MAF isn't a good choice.
smackmybutter535i
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Post by smackmybutter535i »

I am a newbie to performance upgardes on the motor and drivetrain. But electrical and suspension are nothing new to me. I have great wiring skills so when it comes to wiring in a MAF sensor I'm all about it. I just wanna know the diagrams on what to tap and what to use. Thanks. I want to get into autocross so what do you think would be the better diff the 3.46 or the 3.73 from what I hear the 3.73 only gains power in 3rd gear and up. so I was thinking maybe the 3.46 would be better for autocrossing or am I wrong?
Mark 88/M5 Houston
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Post by Mark 88/M5 Houston »

For most autocrossing I would recommend the 3.73 diff. You can get an idea of what is involved with the MAF conversion if you go to Split Second's web site. (http://www.splitsec.com/)
stuartinmn
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Post by stuartinmn »

Duke installed an MAF on the original version of the engine in his car, and documented it pretty well on his website at http://www.cardomain.com/memberpage/269576.
Shawn D.
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Post by Shawn D. »

Whether you go with a 3.46 or 3.73 will depend on the type of courses you run. For the Peachtree Chapter courses, 3.46 is great for me -- aside from starting off, I can stay in 2nd most of the time (bumping off the rev limiter once in a while); if I had a 3.73, I'd probably kick the tail out and have to shift. FWIW, I won my autocross class this year.
fastpat
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Post by fastpat »

[QUOTE="smackmybutter535i"]I heard somwere that I can change my Airflow meter over to a MAF sensor for some good horsepower. Are they full of it? if not how would I go about doing this and without messing anything up?[/QUOTE]

Yes, you can do the above, but it's not for newbies by any stretch. Check out performance chips along with a diff swap, as several others have advised.
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Post by Guest »

[QUOTE="Shawn D."]Whether you go with a 3.46 or 3.73 will depend on the type of courses you run. For the Peachtree Chapter courses, 3.46 is great for me -- aside from starting off, I can stay in 2nd most of the time (bumping off the rev limiter once in a while); if I had a 3.73, I'd probably kick the tail out and have to shift. FWIW, I won my autocross class this year.[/QUOTE]

That's b/c you're a hardass, Shawn ;)

I have the 3.73 lsd in my daily driver (1985 535i) and it's a totally different machine from the 3.25 open diff.
It's pretty buzzy on the highway, but that's the price I pay. Wouldn't bigger anti-sways, stiffer shocks and possibly bigger brakes be a good choice also for the auto-x? Possibly more important than a few hps gain?

HTH
Martin in BellevueWA
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Post by Martin in BellevueWA »

I installed the pro flow maf conversion on my e34 535. I think it is a great modification with documented dyno results. There is a huge torque improvement below 4k rpm. The Split Second maf may be a nicer unit, with additional signal inputs to map against, for improved tuning. Fer instance, a throttle position sensor, or temperature sensor can be used in mapping to smooth running operation when cold, or improve running under load.

I do agree that it may not be the first modification to make to a well-running m30. I've also done the 15 pound flywheel, numerically lower(3.64:1)limited slip differential, reground 284 camshaft, conforti chip, new 21 pound injectors. None of the modifications improve the car, to my liking, as much as the Bilsteins, sport springs & RD anti-sway bars.

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Craig -535i- Seattle
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Post by Craig -535i- Seattle »

You know Martin I'll bet that MAF works great with a turbo. :p
fastpat
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Post by fastpat »

[QUOTE="Martin in BellevueWA"]I installed the pro flow maf conversion on my e34 535. I think it is a great modification with documented dyno results. There is a huge torque improvement below 4k rpm. The Split Second maf may be a nicer unit, with additional signal inputs to map against, for improved tuning. Fer instance, a throttle position sensor, or temperature sensor can be used in mapping to smooth running operation when cold, or improve running under load.

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[/QUOTE]

Did you find a Throttle Position SENSOR, as opposed to the OEM Throttle Position SWITCH, that fits the car with no mods?

And, can you give us a little more infor on the drawing?
Martin in BellevueWA
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Post by Martin in BellevueWA »

The drawing is the harness layout for adding the pro flow maf. The pro flow maf works on 12V, providing a conditioned signal down to the 4.8V max that the motronic dme is looking for. The intake temperature sensor is independent of the maf harness; it is there, but not conditioned by the maf controller. I ended up adding a resistor of 0.8 ohms @ 1 watt, I think, to get the pro flow intake temperature sensor to more closely match the stock intake temperature sensor in the vane air meter. This resistor has greatly improved cold starts on frosty mornings.
After the initial settings from the first visit to the dyno, I soldered the wires together, under the plastic harness box over the injectors. The maf controller is manually adjustable, as well as being able to accept individual maps plotted on the peecee, with a usb connection. There is a map provided to emulate the stock vane air meter from an e34 535, as well as an e28 m5. There is also a setting that allows, from a specific map, the 4 adjustment pots to be 10 times more precise. A wide band oxygen sesnor would help with this level of tuning available.

I do not have a throttle position potentiometer on my car. There is simply the stock throttle position sensor, idicating idle & wide open throttle. The pro flow maf conversion does not accomodate additional inputs for load, making the latest split second unit possibly better. I am curious about the TEC 3 that Duke is installing. Does it provide signals needed by the on board computer? Will the instrument cluster & trip computer function transparently without motronic 1.3? True sequential injection seems like a huge leap ahead of the motronic 1.3.

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[Edit by Martin in BellevueWA on [TIME]1107706426[/TIME]]
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