Ed Clark
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Founding Member/Moderator
Join Date: Sep 2003
Location: Virginia Beach, VA
Posts: 2,337
MAF replacement
Folks,
I've been looking through the threads here and have noticed a trend. This has been discussed before but I'm going to be more blunt.
This trend is mass air meter problems from needlessly changing out a perfectly working stock MAF sensor.
The real problem is that these problems are owner induced almost 100 percent of the time. They start the instant an aftermarket meter is ordered and installed for a car that doesn't need one.
The worst culprit is C&L (sorry C&L). Folks buy these cause they are cheap and appear to be easy power gains. I recently had to retune one of these meters that was installed on a near stock 99GT and had the full C&L treatment on the intake side. IT WAS 35% LEAN ACROSS THE ENTIRE RANGE. This is not uncommon.
ProM meters are better but can still be commonly far enough off to make the car run poorly. Even meters calibrated for stock injectors with a stock curve can vary from stock specs enough to cause issues. Also the exact location and orientation of the MAF can have great affects on the mixture that aren't the MAF sensor's fault. The larger the injector calibration on the MAF sensor the greater the likelyhood of the error.
The computer is capable of pulling about 20 percent fuel to correct rich and adding about 30 percent to correct for lean. Now even though the computer can learn and make these corrections it doesn't mean that it does it good enough to make the car run under all conditions correctly. It can't. It's said that power gains from a MAF swap come from leaning the mixture. But computer is going to try to correct any lean mixture based on O2 sensor voltages. In stock form the computer will even apply these trends learned to WOT.
Then say throw in a mail order chip or a self tuning device and your now hosed. It will run like crap. So a custom tune is then required to reestablish a correct Mass air transfer curve. Once that's done where are you going to get the power gain from? In fact even once corrected it's probably not as accurate as the stock meter.
My suggestions are:
1. Don't buy an aftermarket MAF as a POWER MOD. You buy one if you need to meter more air for your combination. Mainly supercharged setups. I've yet to see a NA 2v peg a stock MAF. Close but not yet. Maybe Ken will.
2. While most tuners can recalibrate any injector/MAF calibration combos try to keep MAFs calibrated for the injectors in use. This allows for simple troubleshooting by simply removing custom chips. The car should still run "OKAY".
3. Keep the screen installed, it's there for reason and it's not trapping debris.
4. Try to only use kits that mount the air filter directly to the front of the MAF sensor.
5. I've never seen an aftermarket MAF that didn't need to be retuned to some degree no matter the calibration. If you have a an aftermarket MAF you probably need a custom tune. If you don't your one of the lucky few.
6. Don't modify the stock MAF. And that means don't cut out the post. It's there for a good reason, air flows around it just fine and removing it WILL affect calibration of the meter. Thus causing the same kind of issues as an aftermarket MAF sensor.
Bottom line is the MAF isn't a restriction for large percentage of people. The Ford meters are more consistant than any aftermarket meter that I've seen so why spend money on them you don't need to.
Ed
