Written by: Jonathan Belanger
I just read Part 1 of the Electronic Fuel Management article with great interest. I found the article well written. There was, however, some omitted information.
First off, the MAP sensor is used in conjunction with an air temperature sensor to determine the density of the air charge within the manifold. It is this information that adjusts the fuel delivery for things like altitude and temperature.
Additionally, there is another style of EFI system that was not presented. This type of system uses a titanium wire in an air flow housing placed before the throttle body. This replaces the combination of MAP and Air Temp sensors.
The wire is electrically heated and when air passes through the sensor, the volume and temperature of the air charge is determine.
This system is better at adjusting for altitude and temperature and meters the air flow much better than the MAP/Air Temp sensor combination.
In the mid-80s Ford introduced the V8 Mustang with the MAP/Air Temp Sensor combination and switched to the Air Flow Sensor a year or two later.
Fascinating information, thanks so much for sending it. The article we posted is a fairly elementary one targeted at introducing snowmobilers to the various electronic controls being used specifically on sleds today.
There are three more follow-up segments to this article that will be coming out on the web in the next few days and then another whole series on 2-stroke electronics that will be posted after the December issue of Supertrax is out. Some of the missing info you mentioned may be mentioned in the other segments.
I’d never heard of the titanium wire system you wrote about and would love to learn more about it. Please send me a link if you have any more info.