What to set Fuel Pressure at with these mods...

[Jeff@Slowboy]

Mods:
evo3 16g
turboback exhaust
safc2
slowboy 650cc injectors
walboro fuel pump

What is the stock fuel pressure for a 2g? and what will we have to turn it down to, to make sure we dont get the FPR overrun thing

We are looking to run like 21-22psi, and we have a wideband and datalogger to watch fuel and timing (what should timing be at?)

Thanks guys

Jeff

 

[StaticXMtrsprts]

43.5 psi is the stock fuel pressure.

 

[femmeDSM]

Which Walbro pump do you have? Might also help to fill out your vehicle profile

Stock fuel pressure for a 2g is as follows:

Vacuum line detatched:
2g Turbo: 42-45 psi

Vacuum line attached:
approx. 33 psi

"Stock" Timing for the 4G63 is 5* BTDC

How are you planning on setting fuel pressure? What AFPR are you using?
The point of an AFPR is that you can use most aftermarket high-flow fuel pumps without fear of overrun - it's the stock fuel pressure regulator that will overrun (and those will usually only overrun with a Walbro 255 or higher - not a 190)

 

[andymoraitis]

As mentioned above, 43.5 is correct base fuel pressure with the vacuum line off. As far as timing, this will be subject to the correction factor for airflow that you plug into the AFC. The issue will come about that the more you lean it out to approach target A/F, the more you'll subtract airflow and the more timing advance you'll add.

Logging it is the only way to tell for sure.

Andy

 

[Jeff@Slowboy]

Which Walbro pump do you have? Might also help to fill out your vehicle profile

Stock fuel pressure for a 2g is as follows:

Vacuum line detatched:
2g Turbo: 42-45 psi

Vacuum line attached:
approx. 33 psi

"Stock" Timing for the 4G63 is 5* BTDC

How are you planning on setting fuel pressure? What AFPR are you using?
The point of an AFPR is that you can use most aftermarket high-flow fuel pumps without fear of overrun - it's the stock fuel pressure regulator that will overrun (and those will usually only overrun with a Walbro 255 or higher - not a 190)

So are you saying we should keep the fuel pressure at stock levels with the new afpr. We are using the aeromotive fpr, and the walbro 255 fuel pump. As far as mods. The car has safc2, full turbo back 3 inch exhaust, evo16g, evo o2 housing, fic 650cc injectors, ngk wideband, injen intake, sbr fmic, turbo xs boost controller.

 

[andymoraitis]

So are you saying we should keep the fuel pressure at stock levels with the new afpr. We are using the aeromotive fpr, and the walbro 255 fuel pump. As far as mods. The car has safc2, full turbo back 3 inch exhaust, evo16g, evo o2 housing, fic 650cc injectors, ngk wideband, injen intake, sbr fmic, turbo xs boost controller.

Yes you should. 650's on an EVO III won't run into high IDC's and since you have plenty of injector headroom, the FPR exists to stop overrun from the 255, not to compensate for injectors that are at max IDC thereby requiring more volume. If you had 550's, I'd have you log and then add fuel pressure so that the injectors could squeeze more volume.

Make sense?

Andy

 

[Jeff@Slowboy]

Yes you should. 650's on an EVO III won't run into high IDC's and since you have plenty of injector headroom, the FPR exists to stop overrun from the 255, not to compensate for injectors that are at max IDC thereby requiring more volume. If you had 550's, I'd have you log and then add fuel pressure so that the injectors could squeeze more volume.

Make sense?

Andy

Yea sounds good so we will leave it at the stock fuel pressure. What vac line should we use. One right from the intake manifold.

 

[femmeDSM]

Yup
Once again, Andy's on top of things.

BTW, just for what it's worth, you mentioned earlier wanting to set fuel pressure to 21psi...That would be barely enough pressure to open the stock fpr. I doubt your car would even run with that fuel pressure.

Mine wouldn't, anyway.

 

[Jeff@Slowboy]

Yup
Once again, Andy's on top of things.

BTW, just for what it's worth, you mentioned earlier wanting to set fuel pressure to 21psi...That would be barely enough pressure to open the stock fpr. I doubt your car would even run with that fuel pressure.

Mine wouldn't, anyway.

No what I meant was boost at 21 psi not fuel pressure sorry for the mix up

 

[femmeDSM]

No what I meant was boost at 21 psi not fuel pressure sorry for the mix up

Haha, that makes more sense. I went back and read your post like 3 times, and I still never caught that. I was like WTF 21psi? How in the.....?

.

My bad, it's been a long night

 

[andymoraitis]

It's late and Claire and I get tired and a bit loopy.

Your combination sounds fine. Since you have a wideband, tune for a target AFR or 11.5:1 or so on pump gas, log and look for dips in timing at 21-22psi that would indicate knock. Remember that on the 2G ECU, timing is held at 7 counts and 1 degree is subtracted for every 3 degrees above that incrementally. So if you see timing at the top of third go from 22 to 20, you know that you had 13 counts of knock.

Conversely, if you're not seeing any knock at 21-22, keep adding boost until you see enough knock to "hold" timing (7 counts) and then back it down a couple of psi and re-log. You could lean out the AFR in a case like that, but the general rule is that boost over timing on pump gas and a solid AFR will make more power than a leaner AFR and more timing on less boost. On race gas, you want it lean with plenty of boost AND advance since the knock threshold of race fuel is so much higher. The AFC will queer things as I mentioned above and it's a bit of a tail chase, but I don't see major issues running that kind of boost on 93 pump with your fuel setup and FMIC.

Let us know how it goes and if you need a hand,

Andy

 

[Jeff@Slowboy]

It's late and Claire and I get tired and a bit loopy.

Your combination sounds fine. Since you have a wideband, tune for a target AFR or 11.5:1 or so on pump gas, log and look for dips in timing at 21-22psi that would indicate knock. Remember that on the 2G ECU, timing is held at 7 counts and 1 degree is subtracted for every 3 degrees above that incrementally. So if you see timing at the top of third go from 22 to 20, you know that you had 13 counts of knock.

Conversely, if you're not seeing any knock at 21-22, keep adding boost until you see enough knock to "hold" timing (7 counts) and then back it down a couple of psi and re-log. You could lean out the AFR in a case like that, but the general rule is that boost over timing on pump gas and a solid AFR will make more power than a leaner AFR and more timing on less boost. On race gas, you want it lean with plenty of boost AND advance since the knock threshold of race fuel is so much higher. The AFC will queer things as I mentioned above and it's a bit of a tail chase, but I don't see major issues running that kind of boost on 93 pump with your fuel setup and FMIC.

Let us know how it goes and if you need a hand,

Andy

Yea thanks, gonna do installs today, and try and get a good tune on it either today or tomorrow. Ill let you guys know and thanks for all the help

 

[Jeff@Slowboy]

Got the wideband in today and did some runs to tune. I DO NOT have the 255 fuel pump or AFPR in yet. And it consitsantly like 9:1. with settings at like -23% across the board. Also how should I have the mbc hooked up right now im running unlimited boost and cant get that straightend out. What are we doing wrong.