What Fuel Pressure?

[rosadod]

Just got my new GN last weekend. I was told that it is running rich and that the fuel pressure may need to be turned down. The exhaust fumes are really bad. Here are a list of the mods:

Craig Te-67 turbo (running 19 lbs boost)
Action Fabrication 15 row stock location intercooler w/electric fan
Translator and 3.5 MAF
62 mm jay jackson tb & upper
Moroso underdrive pulleys
4" ram air
200 R4 tans. built by Rosler w/ manual valve body
3.42 gears
Stock cam
Stock heads
Vigilate converter (4000 stall)
Mosler axles
TA girdle cover
BMR upper contole arms
Box steel lowers
Air bag on pass. side
MSD 50# inj. w/ Lubrant street chip
3" S.S. Houston D/P
3" ATR S.S. single shot (going to dual 2 3/4" dual stainless system from gbodyparts)
93 oct fuel

I just installed a rail mounted fuel pressure gauge today. It measured 55psi w/o vacuum and 47psi w/ vaccum. What Fuel Pressure should I be running?

 

[QUIP'6']

Just got my new GN last weekend. I was told that it is running rich and that the fuel pressure may need to be turned down. The exhaust fumes are really bad. Here are a list of the mods:

Craig Te-67 turbo (running 19 lbs boost)
Action Fabrication 15 row stock location intercooler w/electric fan
Translator and 3.5 MAF
62 mm jay jackson tb & upper
Moroso underdrive pulleys
4" ram air
200 R4 tans. built by Rosler w/ manual valve body
3.42 gears
Stock cam
Stock heads
Vigilate converter (4000 stall)
Mosler axles
TA girdle cover
BMR upper contole arms
Box steel lowers
Air bag on pass. side
MSD 50# inj. w/ Lubrant street chip
3" S.S. Houston D/P
3" ATR S.S. single shot (going to dual 2 3/4" dual stainless system from gbodyparts)
93 oct fuel

I just installed a rail mounted fuel pressure gauge today. It measured 55psi w/o vacuum and 47psi w/ vaccum. What Fuel Pressure should I be running?

43 line off +or- a few

 

[rosadod]

You're the second person to tell me 43 w/ line off... I'll try that. Why do you think the previous owner had the pressure so high?

 

[TurboMonte 2]

You're the second person to tell me 43 w/ line off... I'll try that. Why do you think the previous owner had the pressure so high?

To run higher boost w/o detonation & headgasket replacement...
Depending on what injectors you have, 42-43, vac line off/plugged = typical & perhaps I'm now the 3rd person...

When I first got my GN, boost was set at 23# (what the he!! did I know) & soon after I learned some GN info & installed a FP gauge, found mine was 58#--line-off--idling rich also. Looking back, that's the only thing that probably saved my HG's--as I did, in fact, give it some WOT blasts...

19# is probably near the limit (w/ higher FP & w/o alky) with your larger IC, & who knows how much higher boost the prev owner was trying...

 

[rosadod]

To run higher boost w/o detonation & headgasket replacement...
Depending on what injectors you have, 42-43, vac line off = typical & perhaps I'm now the 3rd person...

Yeah, I'm a newbie. I have MSD 50# injectors.

 

[TurboBuRick]

Yeah, I'm a newbie. I have MSD 50# injectors.

You better be carefull, You go turning down that fp without turning down the boost, it's not going to be pretty. Is there a scanmaster in the car? Do you know how to turn down the boost?

 

[rosadod]

You better be carefull, You go turning down that fp without turning down the boost, it's not going to be pretty. Is there a scanmaster in the car? Do you know how to turn down the boost?

I think I have an idea on how to turn the boost down, but can you explain? I have an OTC scanner that came with the car, but need to read-up on it.

I didn't know I should turn the boost down if I turn the fuel pressure down. So what boost and fuel pressure should I be running? This car will probably very rarely see a track... I just want a fast street car.

 

[Ormand]

The static fuel pressure should be set at whatever the chip was burned for, and that's usually about 43-45 psi. That's good for the max boost that the chip is burned for, too, as long as you have enough injector for that boost. Turning up fuel pressure is usually done when things are pushed beyond their design limits. For example, if the boost is turned up so that the injectors get past 90 or 95% duty cycle, then the O2 readings might get too low at WOT, and turning up the fuel pressure would get the engine rich enough to be safe. But with bigger injectors, that same boost level might be fine with lower fuel pressure. Running pressure higher than 43-45 is risky, because it might get the fuel pump running beyond its limits, and it can also cause some injectors to stick.

 

[rosadod]

The static fuel pressure should be set at whatever the chip was burned for, and that's usually about 43-45 psi. That's good for the max boost that the chip is burned for, too, as long as you have enough injector for that boost. Turning up fuel pressure is usually done when things are pushed beyond their design limits. For example, if the boost is turned up so that the injectors get past 90 or 95% duty cycle, then the O2 readings might get too low at WOT, and turning up the fuel pressure would get the engine rich enough to be safe. But with bigger injectors, that same boost level might be fine with lower fuel pressure. Running pressure higher than 43-45 is risky, because it might get the fuel pump running beyond its limits, and it can also cause some injectors to stick.

So basically I need to figure out what boost/fuel pressure the chip was burned for and make sure the actual fuel pressure matches? Like I said, the previous owner told me that the boost was at about 19. I checked the fuel pressure yesterday and it was 55 w/o the vaccum and 47 w/ it. I just need to figure out what my boost and fuel pressure should be.

 

[rosadod]

You better be carefull, You go turning down that fp without turning down the boost, it's not going to be pretty. Is there a scanmaster in the car? Do you know how to turn down the boost?

I just did a quick search and see poeple running similar boost as me (19) with a lower fuel pressure about (43). I got 55# injectors. Will this boost and fuel pressure be an issue?

 

[yullose]

I'm surprised the car even starts with the FP that high.
43psi with the vac line off is a pretty common baseline to work from.

I'd also have a look at the chip and see if anything is written on it. Sometimes the chip burner will write the recommended fuel psi and boost psi on the chip.

I don't want to knock the Lubrant chip, but MANY guys are VERY happy with chips from TurboTweak Home. So... you might want consider an updated chip too.

Another thing you want to do is, every time you make a change, unplug/re-plug the orange ECM wire so the computer "re-learns" after the new changes.

 

[rosadod]

...I'd also have a look at the chip and see if anything is written on it. Sometimes the chip burner will write the recommended fuel psi and boost psi on the chip...MANY guys are VERY happy with chips from TurboTweak Home. So... you might want consider an updated chip too.

Another thing you want to do is, every time you make a change, unplug/re-plug the orange ECM wire so the computer "re-learns" after the new changes.

Yeah, I ordered an emissions chip from TT last week. I should of ordered a street chip while I was at it I'll probably go ahead and order one and start out fresh.

I'll check my chip later to see if it has anything written on it. Thanks a lot!

 

[rosadod]

Is there any issues with timing that I need to worry about before adjusting the fuel pressure?

 

[QUIP'6']

do you and your car a favor and invest in razors alky kit!!!! will let you run boost levels in the mid to higher 20's and also clean your motor while running it. since your car as mainly a street driven car. gives you better benefits thatn race gas because of the cooling effect. plus you can run a cat and it wont hurt your o2 sensor. Alkycontrol

 

[rosadod]

Here's what's written on my chip:

MSD 50#
20 degrees - 18 degrees
62 MPH TCC
18 PSI & Anti-Stall

Does this mean the converter locks up at 62 MPH? What is anti-stall?

With this info, should I turn my fuel pressure down to 43 w/o vaccum? This is done with the car running, right?

 

[TurboMonte 2]

You should turn the boost down to around 15# max to start with. Many adj wastegate rods adjust at approx 1#/full turn. You lengthen rod to lengthen engine life (reduce boost) & conversely shorten rod to shorten engine life (increase boost). [I assume you have a good boost gauge--if not, then this would be a 1st addition...]

Then you can reduce FP to about 43#, vac line off reg'r,,, engine running/idling--warmed up.

If you don't already have one, your 1st investment/installation should be a Scanmaster, Ver 2.1. Contact Mike at FULL THROTTLE SPEED - Store Front Page .

 

[rosadod]

You should turn the boost down to around 15# max to start with. Many adj wastegate rods adjust at approx 1#/full turn. You lengthen rod to lengthen engine life (reduce boost) & conversely shorten rod to shorten engine life (increase boost). [I assume you have a good boost gauge--if not, then this would be a 1st addition...]

Then you can reduce FP to about 43#, vac line off reg'r,,, engine running/idling--warmed up.

If you don't already have one, your 1st investment/installation should be a Scanmaster, Ver 2.1. Contact Mike at FULL THROTTLE SPEED - Store Front Page .

Why do you suggest I go down to 15#? I have an Autometer boost gauge, but I've never adjusted the wastegate rod and really don't know how to test to ensure the correct boost level after I adjust it... can you tell me? BTW, I have an OTC scanner. That's good enough, right?

 

[rosadod]

ttt

 

[QUIP'6']

Why do you suggest I go down to 15#? I have an Autometer boost gauge, but I've never adjusted the wastegate rod and really don't know how to test to ensure the correct boost level after I adjust it... can you tell me? BTW, I have an OTC scanner. That's good enough, right?

because 19 is too high for pump gas and where your fuel pressure was it may have or was helping detonation a little so if you lower to 43 psi then you will dramatically lower your o2 volts and detonate bad.what you were doing was sacrificing idle and lower rpm power to run higher boost at higher rpm therefore if you lower to 15 psi you should be where your motor can tolorate the lower octane 93. if you have a fine thead wastegate then its probably 1 psi per revolution if its course thread its probably 1 psi per 1/2 revolution. what you want to do is lengthen the rod to lower boost i would say turn 3 turns counterclockwise if you standing at the passenger fender. then test out. good luck brian

 

[yullose]

Shortening the rod will raise boost.

A good starting point is to turn it out (lengthen it) to the point where it will 'almost' slip on to the arm, and will need to be pulled approx 1/8" to put on. That should lower boost enough to be safe for testing.