Progress Thread Budget 89 GT

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Anti_Hero0932

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Jan 29, 2012
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alright. well i made me a hose at work for the fuel gauge... with the car running it shows 30psi now. the other night it said 35.

when i originally started tuning this car it was on 43psi.
 

Anti_Hero0932

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Jan 29, 2012
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its running at 30psi idling with the line on. seems low.

before i adjusted it, it ran at 43psi with the line on.

so when i went to drive it again it was waaaayyyy lean.
 

stanglx2002

Mod Dude
Jul 7, 2005
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its running at 30psi idling with the line on. seems low.

before i adjusted it, it ran at 43psi with the line on.

so when i went to drive it again it was waaaayyyy lean.
That sounds about normal with the line "ON". If you were seeing 43 psi with the line "ON" then you were probably in the 48-50 psi range with the line "OFF". The injector specs that are provided by manufacturers are tested at 39.5 psi WOT (vacuum line OFF). When you increase the fuel pressure higher than that amount it increases the amount the injector is able to squirt. This means that if you had 50lb injectors and increased the fuel pressure to like 55 psi then they would be rated to around 55-58lb injectors.

This is the reason why you saw the AFR's go lean due to less fuel being squirted due to the lower psi. If you lowered the fuel pressure you will need to increase your VE table to compensate for the fueling change.

You should always test the fuel pressure with the vacuum line off as that is the max psi the fuel pressure will allow.
 

stanglx2002

Mod Dude
Jul 7, 2005
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Just making sure we are on the same page that you don't have to drive the car for this test. Just take the vacuum line off the fuel pressure regulator and start the car. Read the gauge and see what it is running. Adjust the regulator to 39-40 psi if needed. Turn off the car and put the vacuum line back on the car.

Im pretty sure we are on the same page but just wanted to make sure.
 

a91what

SendMeUrDataLog
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Apr 6, 2011
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Yeah dont pay anyone to tune on your car, well unless you want to pay me... :p

He is not going to find anymore power than you could [well i am sure he could with timing but thats another animal]
Even leaning the engine out in boost wont find you a substantial power increase, may a handful at most... I am not against leaning you out to around 11.8-12 AFR in boost that alone will bring the injector duty% down.
I perfer to do safe tunes, as i cannot be with the car during the process.
 

Anti_Hero0932

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nah steve you have been good to me. im going to put the regulator back to how it was load your last tune you sent me in and see what it says. im gonna watch the gauge as well and see what it does. that will be in about 3 hours on lunch. this set up should work ive seen many people do it. on the REV 3.0.0 of my tune was the duty % really high too?
 

a91what

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before the added fuel when she was around 12.2 AFR in boost the numbers show 85% duty cycle with a 18-19mS pw and my calcs show a HP of 440
 

Anti_Hero0932

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ok. im gonna set it back how it was and run the rev 3.0 and see what the data log says. it was set really low how i had it may have been working extra hard.
 

Anti_Hero0932

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drove the car last night with the fuel pressure back to where it was. the fuel pressure didnt drop and it acted decent. it was a little "jerky" i would call it. i looked at the fuel tables on my scatter plot and it was asking for 5-6 percent in a few places. i changed the VE table accordingly. ill drive it again and tonight and see what happens. if i dont need any more big changes ill post the tune and data log. it may need some cell smoothing or something im not sure.
 

Anti_Hero0932

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UPDATE- Cars running pretty good. not asking for much fuel anymore. @a91what not sure if im doing this right or not but the number were jumping around a bit like from 130-150 on the VE table going left to right in the same column so i tried to smooth alot of the cells out.

gonna drive it again tonight and see what it says and how it acts.
 

Anti_Hero0932

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i should re say that i guess. the columns would look like this

130 131 150 156 162
so i would smooth it out a little like
131 145 150 156 162
 

a91what

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yes thats correct, now the numbers will not always increase left to right, sometimes the values will drop as the VE of the engine decreases after the peak.
 

Anti_Hero0932

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LET ME START OF BY SAYING I KNOW MY FUEL PRESSURE I WRONG AT IDLE

ok, my brass stud that make it to where i can adjust the pressure regulator is seized up so i cant adjust it till i find a place to buy just the stud and jam nut.

at idle with the line off the regulator and plugged. 45psi
at idle normally 43ish

driving normally it acts normal.

if i run the car like it owes me money i have seen the gauge get sucked down as far as 40PSI

if i set my fuel pressure lower using a shim under the jam nut which i dont want to do im pretty sure its sucking it pretty low causeing the lean condiotion. im guessing this would make the injectors call for more fuel? im thinking i need a new pump and a the parts to fix my regulator?

the car runs decent right now. its pretty smooth. its starting to make more power down low coming into boost it seems like but it does die from time to time :-(

here is the tune and data log.

i seen LMR sells a 340 aeromotive pretty reasonable. i seen quiet a few guys run them on boosted fox's.
 

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a91what

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Mod Dude
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OK so i did not do a fuel trim because i altered the AFR table, we are now targeting higher AFR values.. The injectors are still above the PW and duty cycle i would like to see at high rpm. So removing some fuel will help with the issue. The targets are now in the higher 11, this is still safe. The torque down low is likely the timing table change we made in the last revision, I made another in this one to raise the timing just under the idle range to help catch a falling idle. Hopefully this will help with the stalling issue.

We want to stay below 12AFR in boost
 

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Anti_Hero0932

5 Year Member
Jan 29, 2012
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any input on the pump/fuel pressure? or do you think its the injectors still? i have seen guys run bigger combos on smaller injectors.. like 47s but i know every combo is different.