Author Topic: Fuel Pessure  (Read 442 times)

Offline Ian Johnson

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Fuel Pessure
« on: December 17, 2016, 03:20:56 pm »
I had my Cup car on the dyno a few days go..............the car made good power but a bit lower than the previous owner had suggested, the AFR graph showed the car running rich cumulating at 10:1 at wide open throttle from around 6000 rpm (limiter is about 7850rpm).

Today I have checked the fuel pressure and was a bit shocked to see 4.5bar. Did a little research and from what I can see stock is around 3bar without vacuum at tickover. Can anyone throw any reasons as to why it would be set that high?

Here is the AFR-Boost graph for info.


Offline Andy

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Re: Fuel Pessure
« Reply #1 on: December 26, 2016, 10:45:36 pm »
The last rpm setpoint in the map is 6500rpm by default (if memory serves), so unless you start messing with the scaling of the map fuelling at top end is a bit of a compromise.

Fuel pressure (gauge) = 3 bar + manifold pressure. So if you're running 1.5 bar of boost, then 4.5 bar gauge is correct.

Offline Ian Johnson

  • Posts: 90
Re: Fuel Pessure
« Reply #2 on: December 27, 2016, 06:33:57 pm »
hi andy

Fuel pressure was 4.5 at idle with Vacuum..............boost is max 11psi. Iv now adjusted to stock fuel pressure at idle without vacuum to 3bar. I'm wondering if it may have been set high if there was an issue with the throttle body vacuum take off. I have checked it and although it is only a very small hole/restrictor in the take off it is clear.

Guess I will find out more when I do my first test day in Feb.