AFPR useless?
Thread Starter
TECH Resident
Joined: Dec 2005
Posts: 856
Likes: 0
From: In a house
AFPR useless? According to ws6.com, an AFPR is a nice little mod but this is always what he claims..
"One thing that I have found after some time with this mod is that the stock computer is quite smart. After lowering fuel pressure to achieve a better air/fuel ratio, the computer sees this at part throttle and adds injector pulsewidth to compensate" taken from ws6.com.
So it pretty much sends you back to where you started less the HP. Would a mail order tune be able to get all the benefits of an AFPR?
"One thing that I have found after some time with this mod is that the stock computer is quite smart. After lowering fuel pressure to achieve a better air/fuel ratio, the computer sees this at part throttle and adds injector pulsewidth to compensate" taken from ws6.com.
So it pretty much sends you back to where you started less the HP. Would a mail order tune be able to get all the benefits of an AFPR?
TECH Senior Member
iTrader: (3)
Joined: Oct 2006
Posts: 7,564
Likes: 4
From: Decatur, TN (N-W of Athens)
Well, I don't know how similar the TPI computer is from the current LT1 (pre OBD2), or even my 93. However with my 91 TPI and a AFPR, I could tell a difference. Both in throttle response and it had a LITTLE more poop. Now, what increasing the FP does, is increase the injector #. So I basically took my 19# factory injectors and made them around 22#, since I was running about 52-55psi.
I'd say
2500ft+ Above Sea Level, work with a little less PSI (try more first though)
Sea Level - 2500ft, start going higher PSI.
I'm sure most know, but for those who don't: Above sea level, you lose oxygen density, so you want to dump in less fuel to get back to your best Air:Fuel ratio. Lower you are, then the more O2 there is, so you can get away with a higher PSI. TPiS (which is close to me, woot) site says that stock LT1's like over 50PSI (It might be over 55, you'd have to check) before you start seeing gains.
My best advice is that you get your own junk laptop with a cable, and some form of software that can data log and tune live, like TunerPro R/T. Then you can fidget with things how even you like. Change tables and the sort. I think you can with an OBD2, but I really don't have a clue. The more PSI with a factory won't do all that much, but then when you change the injector rating in the computer to say 26# (24# stock), it can do more with it.
There's so many things to do when tuning. It's pretty fun to get into. I wish my ECM had the reflashable chip like 94+
I'd be changing **** allllll the time lol
I'd say
2500ft+ Above Sea Level, work with a little less PSI (try more first though)
Sea Level - 2500ft, start going higher PSI.
I'm sure most know, but for those who don't: Above sea level, you lose oxygen density, so you want to dump in less fuel to get back to your best Air:Fuel ratio. Lower you are, then the more O2 there is, so you can get away with a higher PSI. TPiS (which is close to me, woot) site says that stock LT1's like over 50PSI (It might be over 55, you'd have to check) before you start seeing gains.
My best advice is that you get your own junk laptop with a cable, and some form of software that can data log and tune live, like TunerPro R/T. Then you can fidget with things how even you like. Change tables and the sort. I think you can with an OBD2, but I really don't have a clue. The more PSI with a factory won't do all that much, but then when you change the injector rating in the computer to say 26# (24# stock), it can do more with it.
There's so many things to do when tuning. It's pretty fun to get into. I wish my ECM had the reflashable chip like 94+
I'd be changing **** allllll the time lol 
Originally Posted by Bowtie Boy
According to ws6.com, an AFPR is a nice little mod but this is always what he claims..
"One thing that I have found after some time with this mod is that the stock computer is quite smart. After lowering fuel pressure to achieve a better air/fuel ratio, the computer sees this at part throttle and adds injector pulsewidth to compensate" taken from ws6.com.
So it pretty much sends you back to where you started less the HP. Would a mail order tune be able to get all the benefits of an AFPR?
"One thing that I have found after some time with this mod is that the stock computer is quite smart. After lowering fuel pressure to achieve a better air/fuel ratio, the computer sees this at part throttle and adds injector pulsewidth to compensate" taken from ws6.com.
So it pretty much sends you back to where you started less the HP. Would a mail order tune be able to get all the benefits of an AFPR?
Get the tune, it is THE right way to go about this. treat the fuel pressure regulator as a fuel system component NOT a tuning aid. messing with fuel pressure will change the pressure at all running conditions so even IF the computer did not learn it out, like it does, all it would accomplish is correcting one area while messing up the tune elsewhere.
I have an adjustable regulator but only because I got it cheap and a set of 32lbs LS1 injectors cheap. I tried to run the injectors at stock LT1 pressure where they are only 28lbs but was maxing them out so I put on the regulator to give them the 58psi they are rated at and make them 32lbs. I am still pushing them past 85% so I plan to go to something like the SVO 42lbs and back to a stock regulator.
