Odd Question for you guys... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Russell · 08-09-2004, 01:04 AM

Hey guys, two questions here, #1 -- Do the newer fuel injected vehicles have some sort of a butterfly valve on it somewhere to restrict airflow to control the motor's RPM, or is it now done entirely based on the amount of fuel the injectors put it?

And #2 -- Does a diesel motor have the injectors directly in the cylinder, or are they in some sort of a pre-combustion chamber or something?

My father and I got into a disscussion tonight, and he feels that none of the newer vehicles have butterfly valves on them, which doesn't make sense to me, since the vehicle is run based on how much air is entering it as far as I know, and that diesel injectors inject directly into the cylinder. I dunno who is right, so we both decided that we'd let you guys decide

ocbaud · 08-09-2004, 01:16 AM

i thought that the throttle body controlled the air and fuel amount??

*1972C10* · 08-09-2004, 01:22 AM

If your talking about How it raises rpm it has a throttle body most have one single blade The diesels i have seen have injectors on the intake kinda like powerfogger setups for Nos.

Russell · 08-09-2004, 01:33 AM

ah ha, so I am right then, lol

My father figures that the comptuer controls RPMS soley by adjusting the amount of fuel injected...

plumbcut · 08-09-2004, 02:09 AM

there is definately a butterfly (throttle) valve on all gasoline engines.. throttle position, air flow, engine rpm, among other things are factored into the signal that the computer sends to the injector, so that the appropriate amount of fuel is given to the engine...

as for the diesels, there are indirect, and direct injection types.. the differences between the two- i dont know. but I do know that with direct injection type, its injected into the CC just as the name implies. im sure arveetek or someone with some diesel knowledge will chime in

pc

NeCrOmAnCeR · 08-09-2004, 08:01 AM

Gasoline engines use throttles as mentioned. The computer can control idle speed using the "Idle Air Control" a small stepper motor which opens a small air passage allowing more air into the engine. The computer also uses various other sensors to monitor air flow into the engine at off-idle speeds to compute the correct ammount of fuel to add.

The majority of diesels you will come across are direct injection where the injector places the fuel directly into the cylinder. On the newer computer controlled types the duration and ammount of fuel are controlled by the computer to give the desired speed and power. On older engines, individual injectors are actuated with a camshaft lobe and ammount of fuel is controlled with a "rack" which rotated a sleeve in each injector that opened the drain port. Others use a central injection pump which does all the above and sends the pressurized fuel to each injector through steel lines. Like I said above most diesels are direct injection, there are a small ammount which use pre-combustion chambers in the head. The purpose is to cause greater "swirl" and allow more complete combustion. It was apparently found that the same thind could be accomplished other ways.

Hope this helps.

08-09-2004, 01:33 AM	#4
Russell Professional Grade Join Date: May 2003 Location: Fort McMurray, Alberta Posts: 7,915	ah ha, so I am right then, lol My father figures that the comptuer controls RPMS soley by adjusting the amount of fuel injected... __________________ 1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap)

08-09-2004, 01:04 AM	#1
Russell Professional Grade Join Date: May 2003 Location: Fort McMurray, Alberta Posts: 7,915	Odd Question for you guys... Hey guys, two questions here, #1 -- Do the newer fuel injected vehicles have some sort of a butterfly valve on it somewhere to restrict airflow to control the motor's RPM, or is it now done entirely based on the amount of fuel the injectors put it? And #2 -- Does a diesel motor have the injectors directly in the cylinder, or are they in some sort of a pre-combustion chamber or something? My father and I got into a disscussion tonight, and he feels that none of the newer vehicles have butterfly valves on them, which doesn't make sense to me, since the vehicle is run based on how much air is entering it as far as I know, and that diesel injectors inject directly into the cylinder. I dunno who is right, so we both decided that we'd let you guys decide __________________ 1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap)

08-09-2004, 01:16 AM	#2
ocbaud Garage Queen Material Join Date: Oct 2002 Location: USA Posts: 4,129	i thought that the throttle body controlled the air and fuel amount??

08-09-2004, 01:22 AM	#3
1972C10 Account Suspended Join Date: Dec 2003 Location: Texas Posts: 2,686	If your talking about How it raises rpm it has a throttle body most have one single blade The diesels i have seen have injectors on the intake kinda like powerfogger setups for Nos.

08-09-2004, 02:09 AM	#5
plumbcut california fill Join Date: Apr 2004 Location: Sunny So-Cal Posts: 694	there is definately a butterfly (throttle) valve on all gasoline engines.. throttle position, air flow, engine rpm, among other things are factored into the signal that the computer sends to the injector, so that the appropriate amount of fuel is given to the engine... as for the diesels, there are indirect, and direct injection types.. the differences between the two- i dont know. but I do know that with direct injection type, its injected into the CC just as the name implies. im sure arveetek or someone with some diesel knowledge will chime in pc

08-09-2004, 08:01 AM	#6
NeCrOmAnCeR Registered User Join Date: Feb 2004 Location: Hodgenville, Ky Posts: 735	Gasoline engines use throttles as mentioned. The computer can control idle speed using the "Idle Air Control" a small stepper motor which opens a small air passage allowing more air into the engine. The computer also uses various other sensors to monitor air flow into the engine at off-idle speeds to compute the correct ammount of fuel to add. The majority of diesels you will come across are direct injection where the injector places the fuel directly into the cylinder. On the newer computer controlled types the duration and ammount of fuel are controlled by the computer to give the desired speed and power. On older engines, individual injectors are actuated with a camshaft lobe and ammount of fuel is controlled with a "rack" which rotated a sleeve in each injector that opened the drain port. Others use a central injection pump which does all the above and sends the pressurized fuel to each injector through steel lines. Like I said above most diesels are direct injection, there are a small ammount which use pre-combustion chambers in the head. The purpose is to cause greater "swirl" and allow more complete combustion. It was apparently found that the same thind could be accomplished other ways. Hope this helps.



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