MAF info, install & running report

[Brian Olsen]

I got the kit from an outfit named Pro-M. Their web site is www.pro-flow.com. They are primarily oriented toward Ford applications. They are the company that makes the MAF sensor sold by Autothority. I've heard it said the Huntley unit is also made by Pro-M, although I can't say for sure. Both the Autothority and Huntley units are a little different, and it's the proprietary intellectual work that they charge the long dollar for. On the Pro-M home page, follow the "Import Meters" hyperlink for a description of their kit. The kit consists of a cone filter, the 75mm MAF bullet sensor (hot wire), and the adaptor box. Cost is $690. It comes with everything you need to install and run. It takes about two hours to install, and an hour to get to run right. You probably want to install an air-fuel ratio meter, or go to a shop with one, just to make sure you're not running lean. Lean condition at WOT can be disastrous to your engine.
For the ~$1000 you'll save, you'll need to do a little extra work. Like I said, get the AFR checked for optimal performance and safety. Also, you'll need (and I still do) to create a bracket or some other method of bracing the MAF/filter. Currently, mine are being supported by the rubber boot, which is sagging a bit. It works fine, but isn't a nice permanent setup. You'll need to wire in four crimp-fit male spade connectors into the wiring plug for the original air meter. Also you'll need to come up with an acceptable connector scheme for secure connection, and water-proofing. The bare spade connectors are neither. You'll need to use a digital multimeter to set AFR (injector duty cycle) at idle and WOT. The adaptor box has two screwdriver-adjustable trim pots to do this adjustment. The idle adjust is pretty intuitive - adjust for best idle at 800 rpm. If it's too rich, it'll stall. The instructions contain guidelines for setting the WOT adjustment, and doing test runs. I set mine a little on the rich side for a safery margin. Finally, you'll need to find an acceptable mounting location and scheme for the adaptor box. None of these should be show-stoppers. The kit does come with accurate and complete instructions. Their tech. support wasn't great, but I did recieve some good info from fellow Pelicans and Rennlisters. I'd be glad to offer whatever info I can. If you have more specific questions, feel free to get in touch.
I'm also including below a setup/running report I sent to some of the guys who've been helpful.

Guys,

Well, the MAF went in on Saturday. Thanks for all the info and pointers you guys provided. The install was pretty uneventful. It did take a while to adjust the idle properly, but the baseline settings are apparently pretty close. I set the WOT pot. to a little rich, just to have a safety margin against running lean. I might go to a shop with a precision AFRM, just to get things properly dialed in, and to make sure it's not running lean. The only remaining items are to clean up the wiring, make a mounting bracket to stabilize the MAF, and finalize the location of the adapter box in the engine compartment. Pro-M supplies crimp-type male spade connectors to connect to the stock air meter wiring connector. Right now, they're just held in by insertion force. I'd like to find a better way. One that will be more stable, and water-proof. Likewise, I've temporarily mounted the adaptor box on the plastic heater duct to the heater blower. This will have to be moved back, out of the way of rain. What type of mounting bracket are you guys using to stabilize the MAF/filter assembly? Right now, mine's just hanging, and the rubber boot is sagging a bit. So, a bit of finish work is left to be done. The total cost of the Pro-M kit is $690, and everything is there to get up-and-running. It's not a simple plug-and-play like Autothority, but for $1000+, I'm willing to do a little extra work.

I did get a few surprises along the way. First, my stock air box was cracked. Second, an annoying rattle I've been unsuccessfully chasing for three years went away. It sounded like it was coming from the rear passenger speaker. I removed the rear deck assembly, and found nothing. So, apparently this rattle was somehow associated with the stock airbox. Puzzling. Third, the car now starts and goes to a strong, stable idle immediately. Previously, the car would hunt for idle, and just generally act very "groggy" for the first 30 secs. or so, when idling. This was even after replacing the idle stabilizer valve, O2 sensor, DME relay, and cylinder head temp. sensor.

So, how does it run? I wouldn't characterize the change as dramatic, but it does run strong and smooth, all the way up to 6k. It does sound a little nastier. It doesn't pop on deceleration as much as it used to. I'd have to do before-and-after dyno runs to quantify any performance improvement, so I really don't know. Worth it? Yup, I'd do it again. Just fixing the funky idle at startup was worth it. Once at work, a guy walked up to my car after I'd started it (cold), and said "man, this thing sounds like ****". Kinda ticked me off.

Again, thanks guys for the helpful info you shared with me. If I can ever be of assistance, feel free to get in touch.

OK, now I've had the chance to drive my car on familiar routes, and have a better idea what effect the MAF has had:

1) As previously noted, the car will now go immediately to a strong, stable idle when started cold. No groggy hunting like before.

2) Even throttle mid-rpm cruising is smoother.

3) Before, if I was in traffic, and between 1-2k rpm, the car would have at tendency to buck. No more.

4) Throttle response is more immediate.

5) Acceleration has definitely picked up. There's a familiar highway on-ramp on the way to work. It's an elongated S, with a 1/4 mi. straight between turns. I definitely have to brake harder to make the second turn now. Also, the car squats under accelaration noticeably more than before. A quick transition from full accelaration to hard braking produces significantly more squat/dive than previously. The power curve is more linear, as well. Over 5k rpm, it really pulls.

6) I believe my oil temps have decreased slightly. Probably, I'm running a little richer than before.

All in all, for $690, a winner. Just to prove the kit is complete, and can be installed with basic tools, even by a simpleton, I offer the following anecdote: remember me saying I'd have to clean up the wiring? Steve, I asked you about connectors. Well, duh, the kit comes with five 3M 804 connectors. Basically it's a plastic case the accepts the input wire on one side, and fits the male spade connector on the other side. There's a shunt that connects the two. The input wire is held in place by pressure when the connector is snapped closed. So, they provide a good connector that fits the female stock connector just fine, and is waterproof. Well, I couldn't figure out what the 804 connectors were for, so I just crimped the input wires into the spade connectors, and stuck them in the female stock plug. Nice move. So now, I have to call pro-M, and politely ask for a second connector kit to replace the ones I mangled.
I'm surprised Pro-M doesn't market to the Porsche community. They have a decent product at a price point far below what other outfits are asking, and I think they'd get quite a bit of business from Porsche drivers.
Thanks again, guys.

Regards. Brian