Question:
I have a mass airflow (MAF) sensor in my '95 Corvette with a small round screen inside. I've seen aftermarket sensors without the screen, which are claimed to increase airflow and horsepower. Couldn't you accomplish the same thing by removing the screen from the original sensor? What, exactly, is the advantage of an aftermarket unit? If I modify or replace the sensor, will I need to buy a programmer for the ECU, to keep the "Check Engine" light from coming on?
No name given
Via the Internet
Answer:
Yes, you can increase airflow by removing the screen. However, be aware that removing the screen changes the flow rate of the meter and causes the engine's fuel mixture to become leaner. Another reason the factory put a screen there was to act as an "air straightener," to increase laminar airflow. Laminar airflow, sometimes known as streamline flow, occurs when a fluid-in this case, air-flows in parallel layers, with no disruption between the layers. Simply stated, it makes the air straight to get rid of turbulence in the intake tract. There are some factory vehicles that did not come with screens, such as the higher-performance Z06. Delphi worked hand in hand with aftermarket MAF-sensor specialist Granatelli Motorsports to devise a sensor that was ideally calibrated for screenless operation. When considering an aftermarket MAF sensor for your car, only use one that is properly calibrated.
In addition to increased airflow, an aftermarket MAF sensor also promotes freer breathing. It's been said that a stock sensor will flow enough air to support 450 hp, but that doesn't take into consideration the effort it takes for the engine to reach that power level. Think of the OEM sensor as being like a restrictor plate. The engine still has enough power to go 190 mph; it just takes three times as long to get there.
Second, the MAF sensor has a direct effect on the ECM's load table. By increasing airflow, you also advance engine timing. This is another reason why you should only use a calibrated MAF sensor, and not a stock ported or descreened unit. Otherwise, you run the chance of "leaning out" your engine (that is, running too little fuel) while simultaneously advancing the timing-a recipe for disaster. A calibrated MAF sensor will not create this problem. Finally, a calibrated MAF sensor does not require the ECM to be retuned.
Question:
I recently watched the Mecum auction on The Discovery Channel and greatly enjoyed it. I'd like to attend an auction myself, but I don't understand the buying and selling processes. Could you explain how it works?
Sandi
Via the Internet
Answer:
Auctions are great fun to watch, and participating in the bidding is even better. To start the process, you must register as a bidder with the auction house. The easiest route is to preregister by mail or fax, which will require a photo ID. If you prefer, you can always stand in line the day of the auction. You can find the necessary forms on each company's website.
Buyers agree to pay the ending "hammer" price, plus an auction fee. Payment is typically required within one hour of purchase. Auction fees vary. Mecum, for example, has one of the lowest commissions-6 percent for both buyers and sellers-of the major auction houses. Some auction companies have combined fees as high as 20 percent!
When buying at an auction, it's important to remember that the vehicles are sold "as is," and that all bids are final. So before you raise your hand with your bidder number, inspect your prospective buy as thoroughly as possible. Auction companies do not provide any guarantees about the authenticity or originality of the vehicles they sell.