DO MPFI cars have CARB's

kakx · 17th April 2004, 19:40

Do MPFI cars have carbs, if not why ? How does the sys work in MPFI cars.

Shan2nu · 17th April 2004, 19:51

No, carbs and MPFi's are totally different engines.

I ain't no techie but from what i've heard, MPF-i engines control the fuel supply to the enigne depending on the amount of air that has been sucked in. Correct me if i'm wrong.

Does the same happen in Carb engines? Or do those enigines let out designated amounts of fuel irrespective of available air.

Hey Rehaan......i guess it's time for one of those illustrated explainations man. Just love reading them.

Rehaan, from now on will be reffered to as "Mr. Howstuffworks".

Regards...
Shan2nu

Rehaan · 18th April 2004, 13:23

By popular demand>

here is a SUPER SIMPLIFIED diagram.

will edit this post and write about it in a bit.....
plz let me know if u see any mistakes!

To put it simply
The carb has no exact control of how much fuel goes in, it all depends on how much fuel the air passing through the carb atomises and takes with it. Hence it is tough to mantain the ideal air/fuel mix of 14.7 : 1

The fuel injection has injectors which are basically like sprays that can spray in an exact amount of fuel into the intake, and using the information collected by the sensors the ECU calculates how much fuel should be sprayed in, hence keeping an almost perfect air/fuel mix.

cya
Rehaan

Shan2nu · 18th April 2004, 15:14

Hey about the air/fuel ratio of 14.7 :1......does that 14.7 represent the atmospheric pressure?

Regards...
Shan2nu

Rehaan · 18th April 2004, 15:32

interesting.....but nope dont think so.....its the ratio of air to fuel, (in terms of volume)

R

kakx · 21st April 2004, 12:42

Rehaan,

Teacher Teacher, THank you. You are good at it.

Regds
Praful

toyota · 21st April 2004, 18:53

wow rehan that was a good explaination

Rehaan · 24th April 2004, 08:08

Thnx,
glad u guys liked it...had fun making em (and an excuse to procrastinate)

cya
R

ashish112 · 24th April 2004, 23:20

hi rehan
good explanation.u made it look 2 simple. congrats.
but are you sure the 14. 7 :1 the ratio of to fuel is as per volume.
i think it is as per the weight.

Rehaan · 25th April 2004, 00:54

Quote:

Originally Posted by [b

Quote[/b] (ashish112 @ April 24 2004,21:50)]but are you sure the 14. 7 :1 the ratio of to fuel is as per volume.
i think it is as per the weight.

Hey man,

thats right..... i initially wrote molecular volume..but then edited it out to keep it simple.....but i guess the word i should have used was "mass" ...right?

thnx
Rehaan

17th April 2004, 19:40	#1
kakx BHPian Join Date: Apr 2004 Location: Mumbai Posts: 41 Thanked: 0 Times	Do MPFI cars have carbs, if not why ? How does the sys work in MPFI cars.
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17th April 2004, 19:51	#2
Shan2nu Senior - BHPian Join Date: Feb 2004 Location: Hubli - Karnata Posts: 5,533 Thanked: 127 Times View My Garage	No, carbs and MPFi's are totally different engines. I ain't no techie but from what i've heard, MPF-i engines control the fuel supply to the enigne depending on the amount of air that has been sucked in. Correct me if i'm wrong. Does the same happen in Carb engines? Or do those enigines let out designated amounts of fuel irrespective of available air. Hey Rehaan......i guess it's time for one of those illustrated explainations man. Just love reading them. Rehaan, from now on will be reffered to as "Mr. Howstuffworks". Regards... Shan2nu
	() Thanks

18th April 2004, 13:23	#3
Rehaan Team-BHP Support Join Date: Feb 2004 Location: Bombay Posts: 24,199 Thanked: 36,081 Times	By popular demand> here is a SUPER SIMPLIFIED diagram. will edit this post and write about it in a bit..... plz let me know if u see any mistakes! To put it simply The carb has no exact control of how much fuel goes in, it all depends on how much fuel the air passing through the carb atomises and takes with it. Hence it is tough to mantain the ideal air/fuel mix of 14.7 : 1 The fuel injection has injectors which are basically like sprays that can spray in an exact amount of fuel into the intake, and using the information collected by the sensors the ECU calculates how much fuel should be sprayed in, hence keeping an almost perfect air/fuel mix. cya Rehaan
	(2) Thanks

18th April 2004, 15:14	#4
Shan2nu Senior - BHPian Join Date: Feb 2004 Location: Hubli - Karnata Posts: 5,533 Thanked: 127 Times View My Garage	Hey about the air/fuel ratio of 14.7 :1......does that 14.7 represent the atmospheric pressure? Regards... Shan2nu
	() Thanks

18th April 2004, 15:32	#5
Rehaan Team-BHP Support Join Date: Feb 2004 Location: Bombay Posts: 24,199 Thanked: 36,081 Times	interesting.....but nope dont think so.....its the ratio of air to fuel, (in terms of volume) R
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21st April 2004, 12:42	#6
kakx BHPian Join Date: Apr 2004 Location: Mumbai Posts: 41 Thanked: 0 Times	Rehaan, Teacher Teacher, THank you. You are good at it. Regds Praful
	() Thanks

21st April 2004, 18:53	#7
toyota BHPian Join Date: Feb 2004 Location: bangalore Posts: 148 Thanked: 3 Times	wow rehan that was a good explaination
	() Thanks

24th April 2004, 08:08	#8
Rehaan Team-BHP Support Join Date: Feb 2004 Location: Bombay Posts: 24,199 Thanked: 36,081 Times	Thnx, glad u guys liked it...had fun making em (and an excuse to procrastinate) cya R
	() Thanks

24th April 2004, 23:20	#9
ashish112 Newbie Join Date: Apr 2004 Location: mum Posts: 3 Thanked: 0 Times	hi rehan good explanation.u made it look 2 simple. congrats. but are you sure the 14. 7 :1 the ratio of to fuel is as per volume. i think it is as per the weight.
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