Fuel Pressure?

TrickFlowd · Oct 2, 2007

What should my fuel pressure be at with the mods in my signature?

87foxstang · Oct 2, 2007

i would say about 41-42

Foxfan88 · Oct 2, 2007

every car is a little different. i'd just mess with it, i found some hidden power with some FP adjustments.

before my blow i ran around 40

after i added my blower i found it liked 34-35 best. was at the track and noticed like 2 mph difference from the FP change. i am guessing my FMU with my blower is dumping too much gas into the engine so i had to put less FP in to get a better AFR at WOT.

i'd start at 40 and work down some and up some and see what helps out. its not going to be a big difference so it may be hard to tell. if you go to a dyno or track you should be able to see the difference for sure.

my FP tinker netted me like 2 mph at the track, a HUGE gain for just a turn of a screwdriver.

TrickFlowd · Oct 2, 2007

mine is set on 30 at an idle. I think thats low! I have only drove the car once since I bought it this weekend. It runs fine, but I don't wanna mess up the motor by not running enough fuel.

cenok is family · Oct 2, 2007

Foxfan88 said:
every car is a little different. i'd just mess with it, i found some hidden power with some FP adjustments.

before my blow i ran around 40

after i added my blower i found it liked 34-35 best. was at the track and noticed like 2 mph difference from the FP change. i am guessing my FMU with my blower is dumping too much gas into the engine so i had to put less FP in to get a better AFR at WOT.

i'd start at 40 and work down some and up some and see what helps out. its not going to be a big difference so it may be hard to tell. if you go to a dyno or track you should be able to see the difference for sure.

my FP tinker netted me like 2 mph at the track, a HUGE gain for just a turn of a screwdriver.

yeah you're just gonna have to tinker with it man. i had to set my car at 32 which i know is low. but anything above that and it falls on its face at WOT. it's at a shop getting tuned/dynoed right now though. hopefully she'll be running great when i get her back! i'm excited!

vristang · Oct 2, 2007

INmemoryJBC8102 said:
mine is set on 30 at an idle. I think thats low! I have only drove the car once since I bought it this weekend. It runs fine, but I don't wanna mess up the motor by not running enough fuel.

I would suggest bumping it up to around 40psi
Reset the KAM when you do it. (disconnect the battery for 15-30 minutes)

If the car doesn't run well around 40, then you have other issues that should be addressed.

Generally speaking,
If the car doesn't run well in the stock (38-42psi) range, then there is probably an issue that needs to be corrected.

jason

TrickFlowd · Oct 3, 2007

so it should be around 40 at an idle?

bullitstang1313 · Oct 3, 2007

Should be 39-40 with the vacuum line disconnected.

TrickFlowd · Oct 3, 2007

I bumped my FP up to 39psi with the vacuum unhooked. Its reading about 34 at idle now. Seems to run fine throughout the rev, but at idle, I can smell fuel really bad! Seems to be running rich. I could smell fuel pretty good before I adjusted it also. Could this have to do with running o/r hp and race bullets with dumps? I'm about to put on a magna flow catback soon. Car has no back pressure really.

vristang · Oct 3, 2007

back pressure has nothing to do with it...

did you disconnect the battery when you changed the fuel pressure?
The ecu would have adapted to the lower psi by increasing the injector pulsewidth with a multiplier.
You need to disconnect the battery to clear out that multiplier.

If you are still overly rich after resetting the KAM, then you need to pull codes, and we'll work from there...

jason

cenok is family · Oct 3, 2007

jason, are you supposed to adjust the pressure, then disconnect the battery? i've never disconnected my battery after i adjust my fp...

vristang · Oct 4, 2007

The correction factor the ecu is using to bring the AFR toward stoich should be cleared when making ANY change to the fuel or air system.

Leaving the battery connected will keep the Correction Factors for the old setup, so it may take longer for the ecu to develop NEW Correction Factors.

Clearing the KAM any time you make adjustments to the fuel or air systems is just a good habit to get into.
New MAF meter (even if it uses the same injector calibration), then clear the KAM.
New TB, then clear the KAM.
etc.

Besides, it is always a good idea to have the battery disconnected when working under the hood anyway...

Small changes to fuel pressure probably don't require a reset,
but going from 30psi to 40psi... A reset is a good idea...

jason

TrickFlowd · Oct 4, 2007

I did reset the KAM. I unplugged both battery terminals for about 15-20 mins. Then let the car idle for about 5 mins before I drove it. Seems to run fine, but smells like fuel pretty good. How do I check the codes? My MSD 6al isn't hooked up, the kid I bought the car from had it unhooked...so I didn't mess with it. Not real sure how to hook it up anyways. I'm new to this stuff.

TrickFlowd · Oct 5, 2007

anyone know how to check codes?

vristang · Oct 5, 2007

INmemoryJBC8102 said:
I did reset the KAM. I unplugged both battery terminals for about 15-20 mins. Then let the car idle for about 5 mins before I drove it. Seems to run fine, but smells like fuel pretty good. How do I check the codes? My MSD 6al isn't hooked up, the kid I bought the car from had it unhooked...so I didn't mess with it. Not real sure how to hook it up anyways. I'm new to this stuff.

It will take a good 30 minutes for the KAM to adjust to the new hardware settings. You need to hit normal driving cycles during this time.
(I had to drive about an hour total to see my KAMRF's really settle down)

check the last line of my sig for a link to pulling codes.
Also, most Autozone locations will pull them for free. I'm sure other parts stores will as well.
There is a code reader you can get from several places for about $35 too.

jason

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