Need help figuring out newly installed FORE return system issue(s)

[cj428mach]

Also i was told that pressure drop across fuel rail should increase 1 psi for every psi of boost. Mine is going up maybe 2 psi. I was thinking that it should be higher but come to think about it..... is 52 psi right?

You're going to waste a lot of time trying to get your Fuel pressure drop across injectors to read boost reference. Why do you think there's a vacuum/boost reference on the FRPS? Its not there to increase HP. It's there to allow the PCM to see Fuel Rail Pressure while taking boost/vacuum into account.

Disconnect your FRPS vacuum/boost line and plug the line, then go run a datalog and see what the FRPS reports.

You get a lot of people that think there aftermarket Fuel Pressure gauges read the same as the FRPS but they don't. One takes manifold pressure into account the other doesn't.

 

[SVT_Troy]

You're going to waste a lot of time trying to get your Fuel pressure drop across injectors to read boost reference. Why do you think there's a vacuum/boost reference on the FRPS? Its not there to increase HP. It's there to allow the PCM to see Fuel Rail Pressure while taking boost/vacuum into account.

Disconnect your FRPS vacuum/boost line and plug the line, then go run a datalog and see what the FRPS reports.

You get a lot of people that think there aftermarket Fuel Pressure gauges read the same as the FRPS but they don't. One takes manifold pressure into account the other doesn't.

I'm no tuning pro at all. I'm just going off my tuner saying something isn't right and others saying it should be roughly 1psi per lb of boost. I don't care if it's exactly 1psi per lb,I'm just curious to why it's only 2psi higher than base fuel pressure and others is 70ish.

Either way if my car ran fine and my tuner was happy I could care less to the fuel rail drop across injectors psi read.

I did not have these issues prior and now I do after installing one of the most popular and best installing return systems. I'm sure it's operator error somewhere, if not what component is bad.... I just want to figure it out.

Troy


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[cj428mach]

What I'm telling you is you have NORMAL fuel pressure. Your pressure drop across injectors pid is telling you just that.

Read post #9 and #16 maybe it'll help confirm you're chasing your tail on the fuel pressure/supply.

https://www.svtperformance.com/foru...guys-whats-your-fuel-pressure-set-at.1022805/

My car running e85, 22psi logs fuel pressure drop across injectors just like yours. From idle to WOT and back again it hangs right round 50 +/- 1 or 2 psi. Your datalog is saying the supply up to the injectors is good.

 

[cj428mach]

The only time the FRPS will read anything significantly more or less than your base fuel pressure is when you're running a returnless and going out of the throttle and back in again. AKA the cobra hesitation.

I have a log of a friends car I just looked at that was tune by Don Lasota of Lasota racing who wrote many of the books on tuning and Pressure Drop Across Injectors stays solid at his base pressure through his whole WOT run. Thats exactly how my car works and others I've looked at logs for.

 

[SVT_Troy]

I understand what you are saying. My data log still tells me i am going extremely lean. Unless my sensor is bad.

 

[cj428mach]

I understand what you are saying. My data log still tells me i am going extremely lean. Unless my sensor is bad.

That maybe true but your FRPS is saying your fuel system is up to the task.

 

[Soap]

Crazy thought, if mechanically things seem fine and the pressure is good.....but you are getting hung up on the numbers in the datalog......do you have the Analog formulas setup correctly in Livelink for the boost and wideband?

--Joe

 

[SVT_Troy]

Crazy thought, if mechanically things seem fine and the pressure is good.....but you are getting hung up on the numbers in the datalog......do you have the Analog formulas setup correctly in Livelink for the boost and wideband?

--Joe

Joe,

These are the equations that I am understanding to be correct. If not please let me know.

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[cj428mach]

I assume you're using a firewire cable or something similar? Sorry the last Xcal I messed with an X3 not sure how the new ones work.

On my Xcal 3 the colors in the firewire cable didn't match up to the color/pin out chart on the Xcal. I had to use a Multimeter to find the correct wire that I needed to be tapping into for the Xcal3. If I used the color wire that the Xcal3 diagram showed it wasn't the correct wire for the analog I wanted.

 

[MG0h3]

If I remember correctly live link has the equations for different widebands in a drop down box.

I didn't look at the logs on my laptop but do you have a standalone fuel pressure gauge or are you just getting that off the logs?


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[c6zhombre]

I'm sure you have a wideband gauge in the car, correct? It should be obvious if you have input the correct formula into livelink....you should see the log for that analog match up with the gauge. Don't trust the drop down menu for the formula....get the manual for the wideband and make sure you have the correct formula and verify by watching the gauge sweep at idle.

 

[Soap]

Which wideband do you have?

--Joe

 

[SVT_Troy]

I am using a FireWire cable that I did use a multimeter to check pin to pin. Keep in mind this same wideband and FireWire setup worked without issues before I went return. The only change was from An SCT 3 to the new SCT4 handheld.

I posted a pic (post#28) of my formulas in live link on my data logging computer. If those are wrong please let me know.

Joe,

I have the AEM failsafe boost/wideband gauge.


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[Soap]

I posted a pic (post#28) of my formulas in live link on my data logging computer. If those are wrong please let me know.

Joe,

I have the AEM failsafe boost/wideband gauge.

I'm in the process of getting remote tuned right now so I have been datalogging with my new X4 a lot lately. Your formula is drastically different than mine but I am datalogging Lambda instead of A/F. Sorry but I do not know what the formula should be for A/F. Is AEM one of the preloaded formula's? I know my Zeitronix setup was not so I had to type the formula's in myself.

--Joe

 

[SVT_Troy]

I did not use one of the drop down menu formulas. I typed my current formulas in myself based on what I found to be correct online.


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[SVT_Troy]

Well I ended up replacing my long "Its 33" long) silicone boost reference line with a 4AN teflon lined line. That should eliminate leaks and possible line flexing.

Kevin was happy with the Revision 4 tune so he sent me revision 5. ITs back to falling on its face. I made sure i kept my foot off the clutch which could allow the WOT box no lift feature to activate.

 

[SVT_Troy]

Here is the log for revision 5.

Thinking about the WOT box I need to connect my computer and double check the sensitivity settings for the clutch. Other than that I am going to put a jumper bypassing the hobbs switch like previously recommended.

 

[SVT_Troy]

Checked WOT box and settings were fine. I also went back over the firewire cable and formulas in the program. Everything seems to be fine except I noticed that when i wired my data log cable I only wired 1 of the 3 ground wires in the 6 pin firewire. I wired the one primary (black) ground to the optional AEM harness brown analog ground wire instead of all three firewire grounds. I just redid this even though i know it worked last year.