Autothority Mass Air Flow for 3.2L... is it a good upgrade

[cnielsen]

I may have access to an Autothority Mass Air Flow system for a 3.2L and I was wondering if it was a worthwhile upgrade. What performance changes will I notice?

The motor is stock with the exception of lightweight flywheel and clutch, SSI, sport muffler and 20/21 camshafts. Oh yeah, I will also be running a Steve Wong chip.

Thanks, Chris

[Chuck.H]

I did the autothority MAF (along with B&B headers and muffler) about 180k miles ago... The combination of the three (MAF, exhaust, and chip) really woke up my 3.2, so I'm very happy with it. Just adding the MAF to what you have, well I'm not so sure, but IMHO the MAF is way better than the barn door.

Note the chip software changes for the MAF - the old barn door sends two signals, air temp and air volume, and the software calculates air 'mass' from these two.

On the MAF unit, there's only one signal for air mass, so the old DME air temp is fixed by a resistor, and the software no longer uses this in the same way - instead it uses the air volume signal to indicate mass.

The bottom line is your chip needs to be aware there's a MAF attached, I guess I should have just said that.

HTH,
Chuck.H
'89 TurboLookTarga, 257k miles

[WydRyd]

Anything has got to be better than that restrictive AFM flapper door!

IMHO, the difference between an AFM and MAF based car is night and day. The AFM setup feels so much more lethargic/sluggish compared to a MAF setup.

Having said that, a MAP based Pressure Sensing setup is even better

P.S: If you go MAF, it's probably a good idea to upgrade to a slightly larger throttle body in the process

[Carrera3.5L]

Sorry to rain on the parade, but I'll offer a dissenting opinion. The only way that I would ever do this mod is if you got an absolute smoking deal on it and it was just too good to pass up.

All you are going to see is a 4-5 whp difference between a good MAF/HFM kit with Steve's chip programmed for an MAF versus Steve's chip for the AFM by itself on a normally aspirated 3.2L with minor mods.

Steve Wong's HFM5 kit is much nicer but also more expensive. If you've got money to burn his kit is eye candy when popping the decklid open and if nothing else your back end will lose some weight by removing the relatively heavy AFM. It looks good and fits perfect and Steve has the tuning for it down pat. It does run smooth as silk.

While the motor with an AFM may seem lethargic in response when compared to an MAF and thus surely must make more power, the dyno (in least in my instance) doesn't support the claim (either peak power or area under the curve). This was with the entire intake tract opened up (heads, plenums & throttle body). I've run the motor before/after with an HFM5 set-up numerous times on the Dynojet, no guessing here...

I would suggest using Steve's chip programmed for the other mods you already have (exhaust & cams) and call it a day unless you really want to slide down the slippery slope and go into the motor internals, right Merv.

Ralph

[jtratza]

I've had one for about 100k miles and been very happy. Great response. Excellent emission results even without the cat. Last dyno averaged 250 hp with 964 ground cams and stock exhaust with second outlet cut into it. If you can get one used I'd go for it since a new one is expensive and IMHO a luxury at the current price.

[Steve W]

Just a note - the chip that Autothority supplies for their MAF unit is programmed grossly incorrect. If you dyno with an air fuel log, you will see each time that it runs with an AFR in the 10s. Also, each MAF unit was hand trimmed, so often times the output curve of one unit is inconsistent with another, even on the same motor, necessitating a custom tuned chip for best performance. AFR difference between units are usually 1 whole AFR apart. I have had to redo chips for many of them. Also missing from the unit is an air temperature sensor. While a MAF not need a temp sensor to measure air mass, Motronic needs the sensor to trim down the ignition timing curves as air temps rise to prevent predetonation in hot ambient conditions. The Autothority system uses a potentiometer to fine tune the idle mixture, but what they don't tell you is it is it is really taking the place of the air temp sensor with a fixed value.

[WydRyd]

Yeh, I'd tend to agree with Ralph. The MAF won't give you that much more top end HP. I was actually referring to throttle response and crisper acceleration, not necessarily more HP. I've driven a car with a MAF setup and I can say from that experience that it was much nicer in terms of throttle response, compared to my Carrera (back in the day when it was naturally aspirated).

[jtratza]

Steve, do I need to get an AF chart to you for a new chip. I agree the Autothority ship is lacking and have been to busy to get a replacement from you. Looking forward to instruction from you on a replacement. I can send the dyno results if that helps. BTW the potentiameter failed on mine after about 75k miles but was able to replace it after much effort to track down that this was the problem I was having. Thanks for your input.

[don911]

Chris,
I really like my MAF. I also had Steve W make a custom chip for it so I think it's optimized. You can see some dynos from my car in this thread. The only sheet that isn't in the thread is the one below. Steve made some adjustments from the initial chip.

More kudos for Steve W and dyno sheets

[cnielsen]

OK, so I have everything ready to install... The motor is done, SSI, sport muffler, lightweight flywheel installed. Everything runs well as is but now it is time to install my new SW chip (Thanks Steve) and the Autothority MAF.

The first issue is that the connector on the MAF is not the same as the connector on the stock 3.2 wiring harness. Where do you get the proper connector and do the wires line up one for one or is the order witched around?

Thanks, Chris

[jtratza]

Yes Chris there is a special connector or at least mine has one. Its been over 12 years so cannot recall but in looking at mine there is a connector that isn't stock. The connector has a potentiameter in it (I know because mine failed after 8 or so years and had to be replaced for $90). Steve Wong has some points on the use of the potentiameter so I'd suggest contacting him.

[Nine9six]

Originally posted by Carrera3.5L
Sorry to rain on the parade, but I'll offer a dissenting opinion. The only way that I would ever do this mod is if you got an absolute smoking deal on it and it was just too good to pass up.

All you are going to see is a 4-5 whp difference between a good MAF/HFM kit with Steve's chip programmed for an MAF versus Steve's chip for the AFM by itself on a normally aspirated 3.2L with minor mods.

Steve Wong's HFM5 kit is much nicer but also more expensive. If you've got money to burn his kit is eye candy when popping the decklid open and if nothing else your back end will lose some weight by removing the relatively heavy AFM. It looks good and fits perfect and Steve has the tuning for it down pat. It does run smooth as silk.

While the motor with an AFM may seem lethargic in response when compared to an MAF and thus surely must make more power, the dyno (in least in my instance) doesn't support the claim (either peak power or area under the curve). This was with the entire intake tract opened up (heads, plenums & throttle body). I've run the motor before/after with an HFM5 set-up numerous times on the Dynojet, no guessing here...

I would suggest using Steve's chip programmed for the other mods you already have (exhaust & cams) and call it a day unless you really want to slide down the slippery slope and go into the motor internals, right Merv.

Ralph

Although I do not have Steve Wong's HFM5 kit, I did remove an autothority MAF and chip that the po had installed. I am now running a Fabspeed cat bypass, and sport, one in, two out muffler, along with a chip from Steve. IMHO, it feels stronger across the entire rpm range than the autothority MAF.
I'll second what Ralph said...