yeah base pressure should be set around 52 with vac off no matter what, never lower, never higher.

Since my 41 psi was with vacuum line connected and engine running, would the gauge have registered more had I unplugged it? Wondering what effect it has with line connected vs not connected.


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yeah it would have came up a few psi, once you have vacuum on it, it drops a tad. with mine set at 52 , once i connect vac it drops to around 48-50 ish.

Yes. Your engine operates at a vacuum normally.

There is a piece inside the fuel pressure regulator that moves with changes in intake manifold pressure.

When you set it initially, it has to be a atmospheric pressure to give a good baseline for fuel pressure.

When idling (engine operating at vacuum), the regulator will send less fuel (pressure) to the engine since it does not need as much fuel to idle as compared to driving.

When you really get on it, that piece moves to allow less flow back (more resistance to flow), increasing fuel pressure proportional to intake manifold pressure, ensuring that the engine is getting the correct amount of fuel as pressure increases.

Sorry I missed this post. I am curious to know what happened as well, when you've had a little more sleep of course haha.

Without knowing the correlation between pressure and flow exactly, if they set your pressure to 50psi at idle, with the hoses connected, then they did raise your pressure. Roughly guessing, 50 at idle would correlate to near 60 at atmospheric. This would lead to a reduction in duty cycle, given the same injector size.

There is only one thing that can change your duty cycle for a set AFR and injector. Injectors are set because you install them. The AFR piece is for your tuner to play with and is arguably set at a certain value for safety, so I consider this arguably not a variable. This leaves the variable to be pressure. After that comes the issue of the pump being able to support the flow.

I have the CJM S1-SE fuel system with ID 1050x injectors from an Aeromotive 340lph pump with pressure set at 51psi at atmospheric pressure. Looking at my most recent logs, my injector duty is 51%, tuned on 93 octane, while around 11psi.

EDIT: I uploaded a picture of a log to show where my car is at right now for the respective parameters.

Those graphics though....:eek:

Hey Turtle, I see 50%. But that’s at only 6000 RPM. it will keep increasing with RPM. I do not know if they set pressure with line connected or not. I probably had set mine to 42, line connected, engine off, but pump on by using the app.

Cupcakez, let us know what yours pressures are. Curious.

Mine is 54 psi at idle on phunk's gauge. That's stock with the RRP kit.

FPR to be set wo vac line connected

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That is true. I'll see if I haven't solved the tube collapse to stay on it to redline after the rain passes down here.

You’ll probably be in the lows 60s at redline. 50% at 6000 and the increase should be linear.

Update:

Adel, My mechanic, went to route some lines and adjust the fuel pressure on my car yesterday and ended up fixing whatever the issue was. I still do not completely understand what the issue was exactly, but all I know is that:

(1) The rev limiter is now removed
(2) I do not need bigger injectors
(3) Eugene tested the car today doing a pull on a highway and made 14.5psi at 7500 RPM with the same setup as I previously posted with the dyno sheet post. (Air Filter still on there)
(4) The steering rack is being changed hopefully either tonight or tomorrow night and once that is done, I will go pick up my vehicle, get an alignment done at a nearby Firestone and drive back home with it!
(5) No dyno appointments available this week, so I'll try to get in sometime in February to dyno the upper RPM's with Eugene to get that dialed in and all worked out, also to see what numbers it makes for kicks. I'm guessing at this rate it would make (as Topgunz is guessing --> Around 550 RWHP and a little over 425 WTQ) which is perfect as I do not drive it crazy all the time so it will be fine.
(6) After all is said and done (minus the last dyno bit for the upper RPM's), I can finally enjoy and see my car for the first time in 2020!

So woot!

Huge thanks to Eugene my tuner, and Adel my mechanic for all of their hard work and time put into this vehicle, and a huge thanks to you guys (the Z community) for being so supportive of me thus far and for months to come :)

Congratulations Cupcakez! I just got my car back tonight. My local installer guy messed up the stage 3 clutch install so SOHO went and installed a stage 4 and fixed it. This, along with a belt tightening got rid of my slight boost drop I was seeing up top. So I’ve got my flex fuel tune done, and a fresh alignment that also got rid of a very twitchy car. Is Eugene going to add traction control to your tune? It would be nice to see what that ends up looking like. Also, remind us again what your filter, pulley, and impeller mods are. I’m not sure what exactly you ended up with.

He has the V3 Ti blower with the 9lb pulley, 3.00 sc pulley and the stock k&n filter.

Wow just saw this post and your Z is amazing. Way too many questions,but I'll just ask one lol. I saw you got your exhaust work done at mufflertech in Sac everyone keeps referring me there. There was another nizzy on bags that came into my shop and referred me to mufflertech. How do you like their work?

Do you have exhaust clips?

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