i am trying to tune my fuel pressure with a aem fuel rail and regulator
can someone please help me out ??
i don't know what the stock pressure should be, therefore i can't judge what i should set it at it is currently at 52 psi is this right? if not what? IS right!!

 

My stock pressure was at 52 psi

 

i was running with stock injectors and spoon cams and cam gears at 54psi and that was tunned on the dyno for best results !

 

thanks guys!!!

i do have a 5zigen exaust, but forgive my ignorance, but i dont know what the vacume line does and wich way is it better on or of??


[Modified by macdaddy, 6:11 PM 3/18/2002]

 

With your set-up there is not really a need to set the fuel pressure higher. If you had a good header, high flow cat. conv. and less restrictive exhaust you might run a little lean. But right now you wont gain anything with a higher fuel pressure.

 

Vacuum line off.

 

for me it was 52 psi vac. pinched.


[Modified by MPH, 1:17 PM 3/18/2002]

 

I have basic bolt-ons.. V-AFC, DC JDM, cam gears, AEM intake, etc.

44psi was my best setting.

Stock was either 52 or 54 I think.

 

you set your fuel pressure lower then stock and got your best results

just curious cause i have the same setup

intake, headers, high flow, cat back, VAFC I also have TB and Intake manifold

What is you VAFC settings if your at 44psi

 

Correct me if I'm wrong but don¡¦t the ECUs closed loop 02 readings compensate for different fuel pressures?

It has been posted in other threads that even under WOT the ECU will apply a correction factor that is derived from 02 observations under closed loop. This effect would essentially eliminate any effects changing the fuel pressure might have under all load conditions.

 

The ECU will compensate up to a certain point to keep the O2 readings within specs. But if you are running lean and the ECU as reach it's maximum compensation then you need to increase the fuel pressure (or get bigger injectors). If you modify the fuel pressure on a stock ( or near stock) set-up then you will probably not see any big improvement.


[Modified by JPP, 9:45 AM 3/19/2002]

 

I agree that the computer can only correct up to a certain point. I don't agree with the O2 compensating during open loop at WOT. I have read that during open loop, only air metering sensors are used to determine fuel. O2 is left out of the measurements. Also when the ECU reaches it's maximum correction factor and it senses a leaning condition. As the leaning condition continues or increases, the motor creates knock and the knock sensor tells the ECU to pull some of the timing out.

 

What do you guys/gals think of this?

Stock fuel pressure reading ratings are fairly open, between 47 and 54psi. Is it possible that this wide range of stock fuel pressures could account for the most of the power differences between weaker and stronger stock Rs?

If the WOT fuel curves are not effected by any parameters that could be learned by the ECU during closed loop operation (as stated earlier), then it would seem that this wide fuel pressure range could account for measurable differences in engine performance between cars. We know that changing fuel pressures by 2psi can have measurable effect on an engines performance.

This could be an important question for those who suffer with weaker cars and are looking for the cure. Perhaps it lies in the fuel pressure?

Regards,

 

TTT

 

I would have to agree with this statement in thoery. However can we just say : raise the fuel pressure and you will gain HP. I'm not certain that the ECU completely ignores the O2 reading during WOT as this is an important point where you would want the ECU to check for a lean situation and do correction if needed.

Another possibility is that the WOT fuel curve is program in such a way that you will not run lean (on a stock set-up) if the fuel pressure is in the operating range of 47 PSI to 54 PSI.

Just toughts to consider

 

JPP,

It would be nice to know what that black box is up to!

Thanks for your feedback.

 

I don't think think you can say the power difference between 2 stock ITR is totally based on the fuel pressure difference. But it should have something to do with it.

I guess we can make a conclusion on this unless we can get a few stock ITR and dyno test them with a FPR alone!!

 

Yes it would be nice to know exactly what that little box does (maybe I should go work for Honda)

Hopefully, in a few years, we will be able to download the ECU program on a CD, and by working on a virtual dyno on our personal computer we will be able to reprogram every parameter an get 220 WHP.
Then again I might win 10000000$ at the next 6/49 drawing.

 

Then you won't be driving a Honda!