The MFA might not use rpm in it's mpg estimate but... Why would it monitor rpm at all? It certainly does not need it for any other function. If you put it in test mode, one of the readings is rpm.
The mpg would be more accurate this way too since fuel efficency changes with load and rpm. I mean that a 60 mph cruising speed will generate a certain mpg reading in fifth gear and a different mpg reading in fourth. Those of you with fully functioning MFA's can see that too (instantaneous mpg) in test mode. I'm sticking with my theory. -----Original Message----- From: John Caldwell [mailto:[email protected]] Sent: Friday, June 22, 2001 1:45 PM To: Darron Schneider Cc: '[email protected]'; '[email protected]' Subject: RE: MFA Accuracy On Fri, 22 Jun 2001, Darron Schneider wrote: > I've spent a LOT of time looking and I sure can't find one. I now > understand that the MFA estimates mpg by looking at rpm, vacuum, and miles > traveled. It does not measure actual fuel consumption. So I don't see how > a 99.9 reading could be blamed on a vacuum leak since the MFA should > interpret that as WOT or close to it and estimate a low mpg. > Heh.. i had it backwards too. I car pulls MORE vacuum at idle than it does at WOT. Think of it this way... the car is trying to pull in as much air as it possibly can, but since the throttle is closed it's pulling against that resistance. So, the less vacuum you're pulling the more the engine is loaded down. I don't actually think rpm comes in to play at any point in the calculation, because you only need two things to calculate MPG- load and speed. vacuum takes care of load, and speed, well, you get the idea. :) So, if anything- a vacuum leak should make your mfa read lower than normal. I'm assuming when it reads 99.9 mpg that it's just confused... _____________ List Sponsor: http://www.netsville.com To remove yourself from this list, send mail to [email protected] with 'unsubscribe a2_16v' in the body of your message See us on the web at http://www.a2-16v.com Visit the 16V Homepage at http://www.gti16v.org
