34 psi of FP to low?

Deividas93GT · 01-28-2003, 09:10 AM

I have a stock shortblock, afr 165's, FTI cam, and a Performer intake......people have told me that running 34 FP (vac off) with 30lb injectors is to low, but my car runs/idles better with 34FP than with 37-38 which I have it at right now....what do you guys think?

Dark_5.0 · 01-28-2003, 09:53 AM

If you are running 34psi of pressure with 30# injectors then you are over injected.

At 34 psi you are getting a poor spray pattern. Your car would perform better with 24# injectors at a higher psi.

Later,

lx5091 · 01-28-2003, 12:17 PM

unless of course, your upgrading soon, but until then you're probably running slower than you could...

01-28-2003, 01:49 PM

Unless you plan on putting a blower on the car sometime soon...then I'd ditch the 30lbers & get some 24lb. injectors in there.

Deividas93GT · 01-28-2003, 02:28 PM

I bought the combo used, and the guy who had it before used 30lb injectors @ 37psi......I run the same psi, but the car idles bad, but if I would lower it to like 34 the surging idle stops....

01-28-2003, 02:35 PM

I'd get 24lb. injectors & set the fuel pressure at 38-40psi. w/ the vacuum line disconnected from the fuel pressure regulator. Just because you got the surging idle to go away by lowering the fuel pressure...that doesn't mean that that is the optimum setting for your entire powerband. What do you plugs look like?

Deividas93GT · 01-28-2003, 04:01 PM

I'm not saying 34 psi is a good optimum setting for the entire poweraband but it does help my idle, and it might (dyno will tell) be ok for the entire powerband.....the #5 plug was all black and it wet in gas......

red82gt · 01-28-2003, 10:53 PM

How long have you had the pressure set @ 37psi? If you have just set it there, give it a couple of day of driving around for the computer to adapt. The oxygen sensors should be able to tell the computer to shorten the pulse width at idle. Thinking of that, how old are your oxygen sensors? They might be the problem as well.
I don't think that 34#'s will hurt the spray pattern, as long as your above 30lbs, your injectors will give a normal spray pattern. It may just be that 34#'s is the right setup for your car right now (24lb'ers would probably be better, try to find someone who'll swap with you).

USMC302 · 01-29-2003, 01:13 AM

I have 24lbers with the FP at 35psi with clean plugs and no problems

Deividas93GT · 01-29-2003, 08:50 AM

I haven't changed the O2 sensors ever (I had the car for 2 yrs now)......This new combo that I have installed doesn't even have 5 miles on it (Michigan weather

) so maybe I should wait till spring time and see what happens when I "break it in" a little more.

USMC302 · 01-30-2003, 01:12 AM

Damn, Mi was cold, I was at Selfridge National Guard three weeks ago, real close to Deatborn.

USMC302 · 01-30-2003, 01:12 AM

OOps, I meant Dearborn

01-28-2003, 09:10 AM	#1
Deividas93GT Registered Member Join Date: Nov 2002 Location: Dearborn Hts, MI Posts: 13	34 psi of FP to low? I have a stock shortblock, afr 165's, FTI cam, and a Performer intake......people have told me that running 34 FP (vac off) with 30lb injectors is to low, but my car runs/idles better with 34FP than with 37-38 which I have it at right now....what do you guys think? __________________ 93 GT, 5 speed....Full Exhaust, 373's, Nitto DR's....1.92/13.90/97(26x10.5 ET Streets)

01-28-2003, 09:53 AM	#2
Dark_5.0 Registered Member Join Date: Apr 2001 Location: Staging lane Posts: 4,337	If you are running 34psi of pressure with 30# injectors then you are over injected. At 34 psi you are getting a poor spray pattern. Your car would perform better with 24# injectors at a higher psi. Later, __________________ 92' LX-Big brakes, Lots and lots of suspension, GT40X heads, Ported cobra intake, stock cam, Vortech SC trim. 00' Lightning-Stock 88'CRX-13 second ego killer

01-28-2003, 12:17 PM	#3
lx5091 Registered Member Join Date: Nov 2001 Location: Fall River, MA Posts: 467	unless of course, your upgrading soon, but until then you're probably running slower than you could... __________________ '02 Explorer XLT 4.0L --Nice Vehicle '97 Saturn SL1--Soon to be ditched for a Ford!

01-28-2003, 01:49 PM	#4
Simi Stang Guest Posts: n/a	injectors Unless you plan on putting a blower on the car sometime soon...then I'd ditch the 30lbers & get some 24lb. injectors in there.

01-28-2003, 02:35 PM	#6
Simi Stang Guest Posts: n/a	injectors I'd get 24lb. injectors & set the fuel pressure at 38-40psi. w/ the vacuum line disconnected from the fuel pressure regulator. Just because you got the surging idle to go away by lowering the fuel pressure...that doesn't mean that that is the optimum setting for your entire powerband. What do you plugs look like?

01-28-2003, 02:28 PM	#5
Deividas93GT Registered Member Join Date: Nov 2002 Location: Dearborn Hts, MI Posts: 13	I bought the combo used, and the guy who had it before used 30lb injectors @ 37psi......I run the same psi, but the car idles bad, but if I would lower it to like 34 the surging idle stops.... __________________ 93 GT, 5 speed....Full Exhaust, 373's, Nitto DR's....1.92/13.90/97(26x10.5 ET Streets)

01-28-2003, 04:01 PM	#7
Deividas93GT Registered Member Join Date: Nov 2002 Location: Dearborn Hts, MI Posts: 13	I'm not saying 34 psi is a good optimum setting for the entire poweraband but it does help my idle, and it might (dyno will tell) be ok for the entire powerband.....the #5 plug was all black and it wet in gas...... __________________ 93 GT, 5 speed....Full Exhaust, 373's, Nitto DR's....1.92/13.90/97(26x10.5 ET Streets)

01-28-2003, 10:53 PM	#8
red82gt Sober voice of Reason Join Date: Nov 1998 Location: Kelowna, B.C., Canada Posts: 1,514	How long have you had the pressure set @ 37psi? If you have just set it there, give it a couple of day of driving around for the computer to adapt. The oxygen sensors should be able to tell the computer to shorten the pulse width at idle. Thinking of that, how old are your oxygen sensors? They might be the problem as well. I don't think that 34#'s will hurt the spray pattern, as long as your above 30lbs, your injectors will give a normal spray pattern. It may just be that 34#'s is the right setup for your car right now (24lb'ers would probably be better, try to find someone who'll swap with you). __________________ 393W: AFR 205's, hydraulic roller, TKO600.

01-29-2003, 01:13 AM	#9
USMC302 Registered Member Join Date: Apr 2001 Location: Gallatin, Tn Posts: 1,326	I have 24lbers with the FP at 35psi with clean plugs and no problems __________________

01-29-2003, 08:50 AM	#10
Deividas93GT Registered Member Join Date: Nov 2002 Location: Dearborn Hts, MI Posts: 13	I haven't changed the O2 sensors ever (I had the car for 2 yrs now)......This new combo that I have installed doesn't even have 5 miles on it (Michigan weather ) so maybe I should wait till spring time and see what happens when I "break it in" a little more. __________________ 93 GT, 5 speed....Full Exhaust, 373's, Nitto DR's....1.92/13.90/97(26x10.5 ET Streets)

01-30-2003, 01:12 AM	#11
USMC302 Registered Member Join Date: Apr 2001 Location: Gallatin, Tn Posts: 1,326	Damn, Mi was cold, I was at Selfridge National Guard three weeks ago, real close to Deatborn. __________________

01-30-2003, 01:12 AM	#12
USMC302 Registered Member Join Date: Apr 2001 Location: Gallatin, Tn Posts: 1,326	OOps, I meant Dearborn __________________