The MFA does use rpm. Try disconnecting your tach signal wire from the coil. (green on earlier cars, Black/red on Motronic) Your MPG will skyrocket just as if you have a vacuum leak.
Darron Schneider wrote: > 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 _____________ 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
