why such wide variation for fuel pressure?
Thread Starter
B*a*n*n*e*d
iTrader: (1)
Joined: May 2005
Posts: 5,222
Likes: 2
From: sea,WA in my car
why such wide variation for fuel pressure?
b16a2 calls for 40-47psi thats 7 psi of play and can be a big difference in fueling...
that makes little sense since honda is very precise about stuff like that
when i increased fuel psi on my gsr the idle afr dropped from 14.7 to low 13 afr and they are talking about 7 psi difference especially if its said that most of stock engines run very rich during wot
that makes little sense since honda is very precise about stuff like that
when i increased fuel psi on my gsr the idle afr dropped from 14.7 to low 13 afr and they are talking about 7 psi difference especially if its said that most of stock engines run very rich during wot
DO IT ON ALL FOURS
Joined: Sep 2007
Posts: 7,632
Likes: 15
From: IN Your Mind
Re: why such wide variation for fuel pressure?
It is no different than why they have a range for anything. In mass production there are going to be variances that need to be accounted for. You are trying to read into this way too much. Understand the basic concepts first and move forward from there.
Thread Starter
B*a*n*n*e*d
iTrader: (1)
Joined: May 2005
Posts: 5,222
Likes: 2
From: sea,WA in my car
Re: why such wide variation for fuel pressure?
tolerances. 7psi is alot of difference in fueling
maybe you can tell me what basic concepts im not understanding here
maybe you can tell me what basic concepts im not understanding here
B*a*n*n*e*d
Joined: Dec 2008
Posts: 12,028
Likes: 5
Re: why such wide variation for fuel pressure?
The fpr uses vacuum(based on how much the throttle is open) to determine the amount of fuel being sprayed into the cylinder. The more the throttle is open the more fuel the cylinder needs because it needs to run a little richer to account for less efficiency as the ecu has to play catch up to get ignition timing and stoichiometric efficiency.
Honda-Tech Member
Joined: Jul 2006
Posts: 2,817
Likes: 5
From: Kansas
Re: why such wide variation for fuel pressure?
Fuel pressure based on a lot of figures. Most fuel systems specify an operating range, as no one mass-produced component is guaranteed to produce the same fuel pressure. Without a vacuum source on the regulator, the fuel pressure should be constant. As more fuel is drawn into the chamber, fuel pressure may decrease if the pump cannot keep up with demand. (On a stock Honda engine, this is not a problem.)
40-47psi is not a great difference. If the engine runs towards the high side of spec, the injectors will derate fuel to compensate. Likewise, is fuel pressure is on the low side, fuel will increase. The sole goal is the keep the engine running at a desired A/F ratio that meets emissions.
WOT (and thus "47psi") will task the fuel rail heavily, and this mechanical change in pressure will keep more fuel in the rail, to prevent pressure from dropping too low.
Don't think of fuel-injected cars as fueling at 40-47, it will vary as the O2 sensors determine the desired A/F ratio.
40-47psi is not a great difference. If the engine runs towards the high side of spec, the injectors will derate fuel to compensate. Likewise, is fuel pressure is on the low side, fuel will increase. The sole goal is the keep the engine running at a desired A/F ratio that meets emissions.
WOT (and thus "47psi") will task the fuel rail heavily, and this mechanical change in pressure will keep more fuel in the rail, to prevent pressure from dropping too low.
Don't think of fuel-injected cars as fueling at 40-47, it will vary as the O2 sensors determine the desired A/F ratio.
Thread
Thread Starter
Forum
Replies
Last Post
blue_hatch
Honda Civic / Del Sol (1992 - 2000)
7
Mar 6, 2005 11:39 PM