| [GMCnet] Fi Tech - any downwsides [message #299545] |
Sat, 23 April 2016 11:23  |
glwgmc
Messages: 1014
Registered: June 2004
Karma:
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Senior Member |
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Hi Billy,
As I understand it, where a carb uses vacuum and springs to control the amount of fuel introduced into the air stream entering the carb, EFI uses an O2 sensor in the exhaust after combustion to maintain the desired air/fuel ratio for the load. The oxygen content of the air decreases the higher you go so in a conventional carb the relative amount of fuel introduced remains the same. At higher altitudes you run richer and power decreases. With EFI, since it is measuring the fuel to oxygen ratio directly, it can compensate for the change in oxygen available at different altitudes to keep the air/fuel ratio relatively the same. A conventional distributor only knows initial advance, speed of rotation and vacuum and uses those three pieces of information to determine spark advance at any given moment so advance would be the same for the same speed and load at any altitude.
One of our other posters with far more experience with the intricacies of EFI and computer controlled spark advance may be able to give a more compete explanation.
Jerry
Jerry Work
The Dovetail Joint
Fine furniture designed and hand crafted in the 1907 former Masonic Temple building in historic Kerby, OR
glwork@mac.com
http://jerrywork.com
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Message: 11
Date: Sat, 23 Apr 2016 08:39:14 -0500
From: Billy Massey
To: "gmclist@list.gmcnet.org"
Subject: Re: [GMCnet] Fi Tech - any downwsides
Message-ID:
Content-Type: text/plain; charset=UTF-8
Me to. And how does altitude compensation work without connecting to the
distributor?
bdub
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Jerry & Sharon Work
78 Royale
Kerby, OR
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