BigJohnnyturbo

I have a prosport oil pressure gauge laying around. Should i just install it as a fuel pressure gauge until i order one? I believe they're the same. But i could be wrong.

LetsGetThisDone

iTrader: (1)

Yes, it's common to do since it is only active for startup to keep the FPR from seeing vacuum until the engine is running.

Yes, that will work fine.

2winscroll

Again, you don't tune your own cars enough said.

Sure sounds like a poor connection somewhere, is your logged voltage changing when the fan kicks on?

Is your ground wire connected from the intake to the firewall?
You also have a ground wire that goes to the battery to the frame then to the bell housing is that still connected to the frame?

2winscroll

This is what you said when I told a fellow member to drill his siphon. Hummm seems contradictory to me.
I still would have waited until the real electrical issue was found to drill it out.

Glad it helped

LetsGetThisDone

iTrader: (1)

Stock cam/head/motor Evo X on 2000cc injectors, vs the OP here having a built 2.0L, 280 cams, and maybe a ported head with ~1100cc injectors. Two completely different things.

2winscroll

It is even more imperative that you drill the siphon with 2000cc injectors. With smaller injectors you can tune around it, with big ones you can't.

Completely different really? Not really. All FI vehicles should have a linear base fuel pressure with reference to manifold vac/boost, don't you agree?

RightSaid fred

It's there for hot starts to prevent vapour lock
It's not used on cold starts.



Surely nobody in their right mind would disagree.........except for the sake of disagreeing just because I said so.


The computer doesn't have an input for fuel pressure so it's got to be a fixed number.
The number doesn't really matter so long as it's fixed and never changes.

RightSaid fred

That might be yet another problem.
I've seen that happen with a pod filter sucking on hot air.


Another thing to check with the fuel pressure gauge.
There's actually 4 easy numbers to check.
After idling and reading the pressure (33PSI)
Clamp the vac line before shutting off.
Shut it off (33 PSI)
Start it up again, pull the vac line off (43 PSI)

Shut it down (43 PSI)
It'll hold that pressure for several days if not weeks.
If it leaks down straight away, there's a leak.

If the FPR is being outflowed with a 255 pump, then those numbers 33, 33, 43, 43 will be more like 39, 33, 44 and 43.
With a 455 you'll be looking at about 60, 33, 70, 43 unless you've broken the FPR.

But I could be completely wrong?
I might be making it all up?
But how would you know?

BigJohnnyturbo

Yes ground from manifold to firewall is in place with no corrosion. Same with battery-frame-bell housing.


Thank you all for the help so far.


I'm jumping on a plane this morning and heading out of state for a few days, so I wont be able to do all these check until I get back Wednesday.


I just attached my tune, if someone wants to look at it for inconsistencies and errors, please feel free. note that it is a temporary tune, to correct issue before going to Ver7.

LetsGetThisDone

iTrader: (1)

My point was an all stock motor on 2000cc injectors is never going to idle that great if you want it to idle at stoich. So even with doing everything you suggested, the guy with the 2000cc injectors was probably never going to get what he wanted out that setup, he needed to just go with smaller injectors.


I do agree with the latter.

RightSaid fred

That's the most intelligent thing I've seen you post on here.
So you agree with me?

Asmodeus6

iTrader: (7)

You are not wrong. A 255HP overruns the factory FPR. I learned this last year when my hard line (feed) rotted out and I put in a -6AN supply line.

Car was tuned on increased fuel pressure the whole time. The newer larger lines held more volume and dropped the fuel pressure. Car was instantly a door stop.

Rather than retune the entire car - I bought an AFPR. And the line "on" pressure is about what it should be line "off". As soon as I turned up the pressure the car would hold an idle, and all the trims fell back in line.



He's on a mini-battery? How old is it..? Mine last 2 years and the 3rd winter I get all kinds of electrical issues in the car and then I get furious and replace it.

BigJohnnyturbo

Mini battery was in the car when i bought it. Could be 2-3 years old. But i have no clue. Tested it a few times when the alternator went bad. No issues with voltage/resistance, corrosion, or getting continuity on the battery case.

Im back haha.
I will have fuel pressure number up, hopefully by noon.

BigJohnnyturbo

Okay, here are the fuel pressure numbers.

Idle 40-43: afr jumping car struggles to idle
Cruise 37-39: afr jumping
Slight accel 40-43: afr consistent
Wot 40-65 (i did hit 70 in second gear)afr is okay. A tad lean

So its only doing the issue at idle and cruise. Im starting to think is either the inj latency or something with the tps. Its consistent now that i rescaled inj. Not electrical load based

BigJohnnyturbo

When fpr vac is unplugged fuel pressure climbs to 49 then drops to 46