L98 batch fuel injection timing
Thread Starter
Racer
Joined: Aug 2004
Posts: 379
Likes: 170
From: Buffalo Grove IL
L98 batch fuel injection timing
Anyone know how often each batch of fuel injectors fire? Does it vary with RPM or engine load?
I'm trying to get a rough estimate of my injector duty cycle, based on the injector pulse width.
Thanks in advance!
Ben
I'm trying to get a rough estimate of my injector duty cycle, based on the injector pulse width.
Thanks in advance!
Ben
Drifting
Joined: Mar 2005
Posts: 1,923
Likes: 0
From: GA
Originally Posted by bmalec
Anyone know how often each batch of fuel injectors fire? Does it vary with RPM or engine load?
I'm trying to get a rough estimate of my injector duty cycle, based on the injector pulse width.
Thanks in advance!
Ben
I'm trying to get a rough estimate of my injector duty cycle, based on the injector pulse width.
Thanks in advance!
Ben
Safety Car
Joined: Jul 2003
Posts: 3,500
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From: Saratoga Springs NY
2024 C4 of the Year Finalist - Modified
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Not to step on any toes, but it should be half the required fuel, once per revolution,all injectors firing.
Not only do i work on FI systems, but my otherwise useless Chilton manual says this.I guess its good for something other then a beer coaster!!!
Not only do i work on FI systems, but my otherwise useless Chilton manual says this.I guess its good for something other then a beer coaster!!!
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
I dug out my copy of Charles Probst, "Corvette Fuel Injection and Electronic Engine Management, 1982-2001".
This is a book everyone should get. It answers SO many questions about how FI works, it ain't even funny... and not JUST Corvette injection systems - they all work pretty much the same.
I haven't found the exact methodology, except, from what I have seen, the Corvette ECM will increase pressure and lengthen the duty cycle before adding a 2nd shot. This is at WOT.
This is a book everyone should get. It answers SO many questions about how FI works, it ain't even funny... and not JUST Corvette injection systems - they all work pretty much the same.
I haven't found the exact methodology, except, from what I have seen, the Corvette ECM will increase pressure and lengthen the duty cycle before adding a 2nd shot. This is at WOT.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by bogus
...the Corvette ECM will increase pressure and lengthen the duty cycle before adding a 2nd shot. This is at WOT.
Your friend
This is the first I've ever heard of a change in the frequency of fuel shots (other than caused by engine speed) in the batch fire system.
bmalc,
Figure on once per revolution, or twice per cycle.
RACE ON!!!
Drifting
Joined: Mar 2005
Posts: 1,923
Likes: 0
From: GA
Originally Posted by FostersPerformance
Not to step on any toes, but it should be half the required fuel, once per revolution,all injectors firing.
Not only do i work on FI systems, but my otherwise useless Chilton manual says this.I guess its good for something other then a beer coaster!!!
Not only do i work on FI systems, but my otherwise useless Chilton manual says this.I guess its good for something other then a beer coaster!!!
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
Originally Posted by CFI-EFI
Veddy intereshtink! Not only can't the ECM increase the fuel pressure, it has no way of even knowing what it is.
Your friend
This is the first I've ever heard of a change in the frequency of fuel shots (other than caused by engine speed) in the batch fire system.
bmalc,
Figure on once per revolution, or twice per cycle.
RACE ON!!!
Your friend
This is the first I've ever heard of a change in the frequency of fuel shots (other than caused by engine speed) in the batch fire system.
bmalc,
Figure on once per revolution, or twice per cycle.
RACE ON!!!
I think on SFI systems, it will fire 2 squirts of gas at WOT, but I didn't read that far.
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Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by bogus
I miss typed... the ECM doesn't increase the pressure, the FPR does via vacuum, and the ECM increases the length of the shot.
What would be your excuse for THIS post? The vacuum goes to near zero as soon as the throttle is opened wide. It stays at zero through out the rpm range. It doesn't change as the rpms increase, so the regulator cannot increase the fuel pressure as the rpms build. If anything the increase in air flow through a restrictive intake system could allow a small amount of vacuum to build at high rpms. Any vacuum present will work on the fuel pressure regulator to DECREASE the fuel pressure. Let's see...you didn't mis-type, maybe you got something in your eye. Your Friend
RACE ON!!!
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
pressure was probably the wrong word, however the ECM does determine how much fuel is needed at ANY given moment by processing information received from sensors recording engine coolant
temp, exhaust oxyen content, throttle position,intake air mass, engine RPMs vehicle speed and accessory load.
temp, exhaust oxyen content, throttle position,intake air mass, engine RPMs vehicle speed and accessory load.