Are there any EFI engines which run only a MAF meter and no MAP?

I go to an auto tech school and my teacher claims that the MAF can be responsible for calculating engine load. I just dont see how that would workout. He says that many MAF cars dont have a MAP on them. Maybe I just havent seen it.

 

85-89 camaro/ firebird / vette with tpi, and i think 88 ? 89? - 9? mustangs,

 

He's absolutely right. It's kind of hard to explain, but if the computer knows exactly how much air is coming in from the MAF sensor, it can pretty much make it's calculation for injector pulsewidth on that alone. MAP becomes irrelevant. On most cars with MAF and MAP, the MAP is only used to get a base atmospheric pressure reading on startup, then isn't used. To add to the confusion, some cars are coming with baro sensors as well now, which are basically the same thing as MAP but measure atmospheric pressure all the time so the computer can fine tune.

BTW what automotive school are you going to?

 

Its called the University of Northwesten Ohio.
www.unoh.edu

I guess I am just too used to the MAPs on our cars pointing torwards the fuel cell to use, then the MAF taking it from there.

Thanks for the replies.

 

Its easy to explain why the PCM doesn't need MAP for the fuel calculation in an MAF setup.

But even in an MAF setup like the one used in the LT1, the MAP reading is used as an axis of the spark timing map, so you would have to find some sort of alternative measure to set up your spark timing. And, the MAP reading is used for the grid of the long term fuel correction "cells". Maybe by using a table of MAF vs. RPM you could accomplish the same thing. Or even a table of TPS vs. RPM. I know I have at times run my engine (MoTeC ecu) in "alpha-N", which looks only at TPS and RPM for the fuel calculation - OK for a track setup[, but a little "sloppy" for a street car.

Ask him what they use as the ordinate on the timing map, without the MAP sensor.

 

Wow, I didn't realize there were any universities with any full-fledged automotive programs. I go here I must say I am surprised at how easy it becomes to change parts, and how hard it is to correctly diagnose problems. Being a good mechanic isn't as easy as it looks. And of course, anyone can be a bad one. We've got a few of those already in my class.

 

GreenDemon, how do you like UTI? I go to the Orlando campus and have be disapointed at the level of teaching and the quality of students that they allow in.

 

It's a mixed bag. I am rather disappointed with a lot of my peers, but the knowledge is there if you look for it. You have to remember that the level of intelligence of people looking to be mechanics isn't very high, so the curriculum can't be designed to fail them. However, the program at UTI is well placed to put both a wrench slinging ape in a job that will put food on the table and an Einstein tech in a top paying job. I guess it's just the atmosphere- some people are there to learn, some aren't. You just have to rise above it to achieve your goals. I've certainly learned a lot since I came here in October. I'm on my 7th phase right now, still have a 4.0 and perfect attendance.

The most annoying thing there is the whole import vs. domestic thing. It's amazing seeing someone progress into a mechanic and yet still remain so ignorant, and make outlandish claims that just don't make sense.