I have to run but look up IFR and Boost Referenced FPR

 

Giving it my all, I really appreciate any and all help. looking forward to seeing what thread you recommend to read.
really wanting to understand what I'm looking at, I really thought I had a solid grasp on what I was doing but I'm quickly learning I was very wrong.

 

On it.

 

Ok, this needs to be addressed immediately. I was going to ask about it before but I forgot.

The fuel pressure regulator you are getting from the junkyard is not boost referenced.

It is vacuum referenced only. There is a HUGE difference and will cost you another engine.

Fuel injectors are flow rated at zero vacuum "atmospheric pressure"

There is something that's called differential pressure. It refers to the pressure at the top of the injector(fuel rail pressure) and the bottom of the injector(that's in the intake)

When an engine is idling, driving, anything except WOT, there is vacuum in the intake. Because of that vacuum, the injector is going to flow more because the pressure is lower than at the top. A vacuum referenced FPR, lowers the fuel pressure(top of the injector) to keep the differential pressure the same so the injector isn't flowing more than what the PCM thinks it is. When you go WOT and there is no vacuum in the intake, the FPR allows full pressure(whatever the regulator is set at)and the injector flows what it's rated at.

Now lets talk about boost.

All principles are the same. If an injector flows more in vacuum, what do you think it's going to do when there is boost on the bottom side of the injector? Yup, it's going to flow less. The more boost, the less it flows.

That's where a boost referenced FPR comes into play. It can see vacuum AND boost and will adjust the fuel pressure accordingly. All the boost referenced FPR now are 1:1. Which means for every pound of boost, it increases the fuel pressure 1 psi.

Back in the day when we didn't have the tuning capabilities we do now, some were 4:1 or even 7:1

To keep the math simple, lets say your your base fuel pressure is 10psi. If you add 5psi of boost, you have effectively dropped your fuel pressure(flow) to 5psi. If you had an injector that was rated at 40lbs/hr, it now flows 20lbs/hr

The boost is pushing up against the bottom of the injector, preventing the fuel coming out.

The BRFPR, raises the fuel pressure when in boost, keeping the differential pressure the same, keeping your injector flowing what it should.

I hope that made sense and is relative to your situation.

 

The guys that were talking about the IFR table and asking if it's vacuum referenced, this is what they mean.

Most all fuel systems now are returnless, which means the fuel pressure is constant, regardless of engine vacuum.

The principals of differential pressure still apply, So instead of the fuel pressure regulator changing the fuel pressure to compensate for vacuum and fuel flow, the PCM does it with the IFR table.

With a vacuum referenced fuel system, the entire IFR table is going to be the same because the regulator is changing the fuel pressure.

 

thanks for correcting

 

This makes complete sense, I was mistaken when I said that I had a boost reference FPR. You are correct in that I'm using a vacuum reference FPR.
After doing some research its pretty clear to me why you'd want to increase IFR under boost along with the write up provided above, thank you! in my current application using a vacuum referenced FPR on my return style fuel system I don't believe ill need to adjust the IFR anymore than what they are at considering my fuel pressure increases as boost increases, according to my mechanical fuel pressure gauge at roughly 3 psi of boost appx 120kpa my live fuel pressure reading are increased from idling 58psi to just under 65psi with the truck bouncing down the road. so that would mean my IFR is being mechanically increased by my vacuum referenced FPR. In theory I should be good to go with that, right? or am I missing something here

 

The IFR table in my PCM file seems so minimal that I'm almost positive you wouldn't get very accurate adjustments to increased manifold pressure with only 17 columns increasing at just under 1psi per box. Curious now if a Returnless style fuel system IFR tables are any different looking than my Return style table.
In my application I have a differential of 1.36 g/s from 0 psi to 11.6psi in my IFR table. Making me think now it should be flat lined like you're saying at the end of your post considering the vacuum FPR is doing all the adjustments??

 

Get a real boost reference regulator, set your IFR the same across the table and be done with it or start saving up for another engine.

 

The truck is now accepting fuel changes again, I want to thank txh0tb0i972 for adjusting my file and making the necessary corrections to allow for Speed Density to be in effect by fully failing the MAF. it appears my primary issue was the incorrect drop down being selected in the Engine Diag DTC list for P0103 having "No error reported" must have been tricking the PCM like previously mentioned. It needs to "MIL on first error" so that computer actually knows to operate around it instead of seeing there is no error, makes sense now.
I've included updated logs and tune file to show the changes that have been made. Thank you guys again for clearing all this up and giving me more knowledge on the differences in fuel management. I greatly appreciate the effort those of you have put in to help me!

 

Ill start looking into seeing what BRFPR will work for my set up asap. would hate to swap this engine AGAIN

 

Unrelated question, how big is your fuel pump?

 

great question!

Also take a look at your graphs and find out why this is happening I just had a quick glance didnt have a chance to study it.





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I've got 2 fuel pumps, I have the stock pump in the tank with another 340lph pump backing it up. Both pumps are in tank.

 

I'm not really sure how the spark advance and retard tables are read. Haven't spent to much time studying them, sadly I've already blown my engine AGAIN. The inconsistent spark is probably the main factor at this point. The truck is my daily driver and I had to put so many miles on with it running lean the way it was before, that I'm almost positive I've done catastrophic damage by this point. The valve guides are bad everytime I decel get tons of blue smoke out the back, and it starts breaking up really bad after about 5psi of boost. Very disappointing. I'll be pulling another engine from the junkyard this weekend. Heart is broken

 

Sounds like you need a different daily driver. Replacing engines gets old fast

 

honestly you need to find information and read on it. learn and understand it.. when i was learning how to tune i didnt move my car until my idle was on point. once it was on point, i dialed in small areas say 2500 rpm and less..... quick <5 mins drives get data and adjust those areas. rinse and repeat.. the most important thing is correct data, without that your whole tune is out of whack

Also your Throttling should be portioned, increase 500 rpm and hold for 5 -10 secs then move up 500 rpm.and repeat. You should not be going 10tps to 72 tps % slight transitions. DO NOT GET INTO BOOST IF YOU ARE NOT DIALED IN. I would keep it under 100 kpa until you get it dialed in.

 

Not easy to hurt motors at 5 psi. Congrats.

 

Yup, time to pay a professional to tune it as it will be cheaper.