May have solved 100% E85 on LNF puzzle
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Joined: 07-12-08
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From: Houston, TX
really looking forward to this. I have a couple LNFs here that want to run this underlay as well. I wish there was a way to do a switchable tune with the option of adjusting both tunes via hptuners.
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Joined: 04-09-08
Posts: 377
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From: Seattle, WA
Not today, I spent the last two days getting caught up on the work that piled up on Monday from going out and spending most of the day tinkering with this stuff. LOL.
However, I'm going out later to investigate the fuel rail pressure stuff to see what is going on there, and whether it looks like it's going to be a big problem, or not.
I still need to integrate the findings into the layer file for people like you and others.
However, I'm going out later to investigate the fuel rail pressure stuff to see what is going on there, and whether it looks like it's going to be a big problem, or not.
I still need to integrate the findings into the layer file for people like you and others.
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Joined: 05-27-09
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From: In the mountains
Not today, I spent the last two days getting caught up on the work that piled up on Monday from going out and spending most of the day tinkering with this stuff. LOL.
However, I'm going out later to investigate the fuel rail pressure stuff to see what is going on there, and whether it looks like it's going to be a big problem, or not.
I still need to integrate the findings into the layer file for people like you and others.
However, I'm going out later to investigate the fuel rail pressure stuff to see what is going on there, and whether it looks like it's going to be a big problem, or not.
I still need to integrate the findings into the layer file for people like you and others.
Gotta make the donuts.
Thanks for the update.
On the thoughts that the hard line supplying low pressure to the HPFP could indeed be the problem, I'm going to modify it (read drill it out a little bit through the brazing). I undid it, and cannot fit a .065 bit through it...that's a problem. The hard line is 1/8" but the hard line is BRAZED to a flared end, which is a obvious problem. Now im not saying that it's the problem but I took that line off and got less than a liter after an entire minute of bypassing the relay. I also think most of you have forgotten the basics of mechanical injection systems. EVERY system is designed so that it's maximum fueling is available from idle to redline. What it means is the positive displacement of the pump is designed to outpace the injection window. I did simple math on that and even if the efficiency is less than 50% there is good chance you cannot inject more fuel at maximum rail pressure (although I wonder about 2800 psi, the aforementioned may be null considering that) than the pump displaces.
The pump is not gear driven for those who don't know, it's actuated by a three lobed cam at the end of the intake cam, directly on a tool steel piston assembly, internally it's preloaded on a spring. The fuel pressure regulator is the EXACT same regulator used on diesel trucks. The pump itself SHOULD be capable of flowing right up to it's pressure relief preset at maximum injection window at ANY rpm.
Alternate reasons for problems could even be evident in the pressure regulator itself, it's mechanic aspects of control. I know cp3 guys modify the pressure regulator to flow more at it's maximum pressure window but leave the taper alone so it can properly regulate lower pressures and handle low speeds better.
As always decipher my ramblings, some of this is more than worth looking into.
The pump is not gear driven for those who don't know, it's actuated by a three lobed cam at the end of the intake cam, directly on a tool steel piston assembly, internally it's preloaded on a spring. The fuel pressure regulator is the EXACT same regulator used on diesel trucks. The pump itself SHOULD be capable of flowing right up to it's pressure relief preset at maximum injection window at ANY rpm.
Alternate reasons for problems could even be evident in the pressure regulator itself, it's mechanic aspects of control. I know cp3 guys modify the pressure regulator to flow more at it's maximum pressure window but leave the taper alone so it can properly regulate lower pressures and handle low speeds better.
As always decipher my ramblings, some of this is more than worth looking into.
I have a spare HP fuel line I didn't use when I replaced the fuel rail and injectors. A 9/64" (.140x) bit fit tightly into the braised ends. Perhaps I'll remove the original tomorrow and see if this spare would be an upgrade.
Thanks for sharing AGW.
Edit: Misread your post and was looking at the HP side, Iz tired.
Thanks for sharing AGW.
Edit: Misread your post and was looking at the HP side, Iz tired.
Last edited by Iam Broke; Mar 10, 2011 at 05:46 AM.
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Joined: 04-09-08
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From: Seattle, WA
Update from last night's testing. Basically confirmed what Matt said they saw. To wit:
What are we looking at here? You can see the actual fuel rail pressure (FRP), it's the red line in the middle box. The green line is supposed to be desired fuel rail pressure, but it looks like Scan XL has a scaling issue. The regulator command wasn't showing up here (but I did further scanning with a Tech2 and capture regulator command later).
Where the vertical white line is, is where I kicked on my tune to high boost mode in 2nd gear. Up until this point the FRP was right where it was supposed to be, but then you can see the load (boost) jumps, and the FRP takes a dive to 1650psi (it's supposed to stay at 2100psi).
I shift gears, and the pressure rises again - actually overshoots the 2100psi target (likely as the ECM is unwinding the regulator trim), stabilizes at 2100psi again, then falls down to 1020psi (!) once the boost ramps in, in 3rd gear. It climbs up to about 1400psi and stays there until I let off the gas. Note also the injector pulsewidth is almost 14ms with no injector window misfire (!). Thanks advanced injection timing! ;-)
I did some further testing with the Tech2 and watched the regulator command. It seemed to max out at 165*. Even as the actual FRP fell to half of what the desired FRP was, the command seemed to max out at 165* or so. This tells me:
1. The regulator is at the mechanical limit (doubtful because I saw spikes as high as 168-169*)
2. The "closed loop regulator trim" system is at the limit of its adjustment (most likely)
3. A hardcoded software limit for regulator command has been reached
To date, everything Bosch did in the programming for this ECM seems to be centered around close tolerances to factory specifications (injection timing, FRP, etc). That likely means there is more available on the regulator command but it just doesn't go there because the LNF was never designed to need this much fuel mass.
However, this seems to be the end of the line. If we can't get more out of the regulator (reliably) then we can say we've reached the limits of the fueling system mechanically and programatically of the LNF here. We'll have to start looking to increasing the pump capacity, mechanically.
It doesn't mean necessary that we're out of luck (yet), though. With our increased injection window, we can tolerate a lower FRP (and longer IPW) and perhaps slowly ramp it up as RPM climbs.
What are we looking at here? You can see the actual fuel rail pressure (FRP), it's the red line in the middle box. The green line is supposed to be desired fuel rail pressure, but it looks like Scan XL has a scaling issue. The regulator command wasn't showing up here (but I did further scanning with a Tech2 and capture regulator command later).
Where the vertical white line is, is where I kicked on my tune to high boost mode in 2nd gear. Up until this point the FRP was right where it was supposed to be, but then you can see the load (boost) jumps, and the FRP takes a dive to 1650psi (it's supposed to stay at 2100psi).
I shift gears, and the pressure rises again - actually overshoots the 2100psi target (likely as the ECM is unwinding the regulator trim), stabilizes at 2100psi again, then falls down to 1020psi (!) once the boost ramps in, in 3rd gear. It climbs up to about 1400psi and stays there until I let off the gas. Note also the injector pulsewidth is almost 14ms with no injector window misfire (!). Thanks advanced injection timing! ;-)
I did some further testing with the Tech2 and watched the regulator command. It seemed to max out at 165*. Even as the actual FRP fell to half of what the desired FRP was, the command seemed to max out at 165* or so. This tells me:
1. The regulator is at the mechanical limit (doubtful because I saw spikes as high as 168-169*)
2. The "closed loop regulator trim" system is at the limit of its adjustment (most likely)
3. A hardcoded software limit for regulator command has been reached
To date, everything Bosch did in the programming for this ECM seems to be centered around close tolerances to factory specifications (injection timing, FRP, etc). That likely means there is more available on the regulator command but it just doesn't go there because the LNF was never designed to need this much fuel mass.
However, this seems to be the end of the line. If we can't get more out of the regulator (reliably) then we can say we've reached the limits of the fueling system mechanically and programatically of the LNF here. We'll have to start looking to increasing the pump capacity, mechanically.
It doesn't mean necessary that we're out of luck (yet), though. With our increased injection window, we can tolerate a lower FRP (and longer IPW) and perhaps slowly ramp it up as RPM climbs.
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Joined: 04-09-08
Posts: 377
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From: Seattle, WA
That was my theory also, especially when we saw this problem resolve to some degree on the V6 Camaro when we commanded a higher low pressure pump pressure, but Matt said they checked that and saw a constant 60psi on the inlet on the LNF.
OK, now that you posted that I remember Matt asking me to check mine last year but I never got a fitting or transducer to do it. Thanks.
I'm going to pull the supply line off tomorrow to see if it's as small an opening as AGW's is.
I'm going to pull the supply line off tomorrow to see if it's as small an opening as AGW's is.
