Weird thing today...I just got my new B&M FPR & gauge kit from Titan Motorsports (Good guys btw) and installed it; I sort of experimented a little and resulted in weaker performance at the end. My stock at idle was 43psi (w/ hose off) so I tried upping it to 48psi just to see if it helps any but it made my car lag throughout my entire powerband (at least it felt that way). So then I go f@ck-it and put it back to stock at 43psi and wait til I get it dynoed instead, but now it don't even feel like before my whole experimentation--it feels weaker than before I started messing with any of this....all I did was changed it up and right back to stock+resetting the ecu after each. Weird

 

first of all, when you remove the FPR advance hose it will default to the flow rate of the stock FPR's guts which is 52.5psi. at idle it is at 43.5 with the vaccum hose. when you hit the gas, it lets more fuel pressure in. if you install the gague you will notice this as I did with mine. when you remove the hose and adjust it, it is defaulting to a static reading. if you dont plug the hose, you are causing a loss in manifold pressure from a leaking vaccum. a good place to plug the hose is a screw that stands up on the fuel rail. there is the plastic cover that houses the wire harness for the fuel injectors, it is fastened to the IM with two 10mm nuts. you can plug the hose in there, I do it when I want to play at 52.5psi for whatever reason.
I have not yet installed my B/M, however if you are trying to find a static setting w/o advance from the vaccum pump... be sure the vaccum hose is plugged first thing. secondly, I wouldnt adjust this w/o the ability to see the AF curve in its entirety. the stock ECU likes to make 14.7 from 3-5K and 13.7 from 5-8K if you go too lean you will clip the injectors and may cause detonation. I dont know your setup. Go to Hondata's website, on the tech page there are steps to adjusting fuel pressure the proper way

 

It doesnt look like you aware of this. Flow rate is different than pressure. When checking fuel pressure it is done with the vaccum hose disconnected and plugged. Factory says 42-47 psi. The fuel pressure only needs to be a certain pressure above whatever pressure atmosphere fuel is being injected to. If there is vaccum, fuel pressure will be less. With the hose dissconnected and plugged by a bolt, you run max fuel pressure at all times. Too rich, and useless. With wot intake manifold vaccum is 0 same as atmoshperic pressure. The differece in pressure between the manifold and the fuel will also have to raise the same amount. Thats where your static fuel pressure is used. Thats why you set pressure without vaccum, so at wot pressure is sufficient.

If you only have minor bolt ons, a few psi increase will be enough. Make sure that the regulator doesnt have a vaccum leak on it otherwise that may affect the end result. Feel free to adjust it, the AF curve is not affected by a vaccum diaphram unless you get carried away.

 

You guys lost me on the theory stuff about fuel pressure, but I guess I'll just wait to get it tuned on the dyno instead. my setup is as follow though: lsvtec w/ b16a pistons, head milled 40-50thous., p&p head--5angle grind, skunk2 springs and retainers, crower 63402's, adj. cam gears, ITR int. manifold, ported TB, mugen p28, all the little bolt-ons, the b&m adj. FPR+gauge kit, worn piston rings.--->slow a$$ ****.

 

my question is Y do U think U need higher fule pressure than stock? More fule done NOT = more power. You need extra O2 to burn extra fule, and if your not using boost then the stock pressure is the best.

 

So you're saying I just wasted 80bucks that is not necessary for my setup?

 

almost.

it may become necessary if dyno tuning reveals too lean a mixture...

t..

 

I think my mugen p28 is causing me to run rich; so it'll help lean it out when I dyno right?

 

runing too rich can reduce power, running too lean can break your engine...

anyways, check this link for more info, and search the archives for tuning FPR's

http://www.rceng.com/technical.htm

it should help you work out fuel pressure...

t..

 

thanks for the info tinkerbell.

 

well, with just a I/H/E, the B&M FPR is a total waste of money.

20+ dyno pulls proved that.

 

LOL...Damn, I never realized that adjusting the fuel pressure was so involved.
I guess I will have to play with mine a little more then...I knew 55-60 seemed like too much.
I am glad I read this thread.

 

yeah, jeff,

when my B20VTEC was running - i started FP at 55psi and did a WOT pass, shut down and checked the spark plugs(new),

they were too black for me, so i cleaned them, set to 50psi and did another WOT pass and shut down...

they were still a bit black, but i felt more power so i left it there.

this is NOT an accurate way of setting fuel pressure!!!!

but it can give an indication of mixture...

(my DIY A/F monitor showed rich on each pass)

hth,

t..

 

so wouldn't u get more power if it was more leaner or at stoichiometric? (mine also shows rich.)

 

yes, to a point.

(you seem to be learning )

stoich is optimum for "complete combustion" = good emmissions

a bit richer than 14.7:1 gives better power...

t..

maybe someone has some links on A/F tuning?

i dont, but a WWW search should prove fruitful

 

Yes, always willing to learn; appreciate your help very much

 

With press at 60, the a/f is about 2-3 bars into the green at a just about all rpms and the car smokes a bit at extremely hard acceleration.
With the press at 50, the a/f is way in the red except for when I am lightly cruising...soooooo I have it set at 55 right now and the a/f is reading about the same as at 60.
Maybe my O2 is not sending accurate readings, maybe my regulator is jacked up...I dont know.

 

Ok lets throw another variable in there. Say your runnin a different program from stock. Mugen, Skunk2, etc.

Those programs richen the fuel mixture if I'm correct. With this richening of the base fuel map, will it be necessary to further richen with added fuel pressure? As I've heard from numberous people, these programs run pretty rich anyway.

I was wondering because I put in a skunk2 program and I went from running a fairly normal A/F mixture (meter), to always pegged rich (except for decelleration, then would go to full lean). At this time, no adjustable regulator.

Now with the adjustable regulator, I guess I'm wondering if I should just set the pressure back to stock if I'm running the skunk2 program??

And then I'll go from there. I am always running around 550degrees C EGT at normal cruising, and never get hotter than 700degrees C at WOT. I guess it doesn't seem bad. Plugs look pretty good. I'll have to continue to experiment.

 

If you have the POS autometer A/F one like mines, it might be the gauge not interpreting the right ratios, I'm guessing; have heard plenty of negative feedbacks about these A/F meters.

 

Yep, its an Autometer. I am also suspicious of the O2 that I got at the junkyard that no telling what it went through before I got it.

So then what other monitering device (reasonably priced) would be better. An Autometer EGT guage? I am going to be running a 100 shot next week so I need to be able to moniter my a/f relitively accurate.




[Modified by Jeff C, 4:54 PM 10/24/2002]

 

I don't know, I'm stuck w/ the autometer one also. It sucks. Sometimes it gives me lean reading and sometimes rich and sometimes no reading for along time. It worked fine the first couple of months . I notice alot of people are getting the greddy ones now, I wonder if they are any good.

 

There shouldn't be any need to run anythign higher then 60psi MAX with vacuum hose at atomospheric (vac off). It's actually a dangerous situation because you'll probably lean out your injectors on a stock pump. I've seen this first hand on a dyno with fuel pressure anywhere from 50-55psi with vac on.

I've seen that most tuners will end up with settings usually in between 40-45psi vac on (or about 55 max, vac off).

 

I put in a Walbro 255 ho so my injectors will be fine, right.