99.6% Fuel pump commanded DC and 106 psi when in open loop

[mcfarlnd]

Trying to tune in open loop however, when I force open loop, my fuel pressure stays steady at 106psi and my fuel pump commanded is at 99.6%. The max commanded DC in the ECU is 90%, the max in the FSCM opens loop commanded DC is for the flow rate of 0 and 13.5 volts with the multiplier is 89.7. Max desired pressure in the FSCM is 450kpa... the list goes on. Can?t figure out what the problem is and why it is forcing this thing to such dramatic pressure. I do have an 09 CTSV FSCM. This problem only occurs in open loop and will not go away after driving for a day, multiple restarts, etc. When I put it back in closed loop, all returns to normal after a few minutes of driving. I can post the tune and logs a little later.

[mcfarlnd]

Here is a tune, log and layout. It is hard for me to believe no one has observed high fuel pressure with open loop. Unless no one is logging it? Especially the CTSV people. These high pressures cause my VE to go extremely low and when switching back to closed loop, high positive fuel trims are observed.

07+Silverado Turbo.Layout.xml

07 Latest and Greatest open loop 2019.hpt

19-11-22 06-34-09.hpl

Has anyone used Boost Enrichment> Enable MAP to force open loop as opposed to the conventional ECT Open Loop Table and all the other stuff? "[ECM] 2370 - Boost Fuel Enable MAP: This is the minimum MAP to enable the Boost Enrich table. Additionally, above this MAP the engine will enter open loop." Although the EQ Ratio Vs. MAP Enable MAP minimum table is 105 (which i have set at 1.00), the EQ Ratio Vs. MAP table allows you to set it from 0 to 256Kpa. I switched back to my closed loop tune and then adjusted Boost Fuel Enable MAP from 110 Kpa to 2 Kpa and the truck is in open loop all the time and no longer having the high duty cycle problem. The FSCM is adjusting pressure correctly and as requested.

[10_SS]

Here is a tune, log and layout. It is hard for me to believe no one has observed high fuel pressure with open loop. Unless no one is logging it? Especially the CTSV people. These high pressures cause my VE to go extremely low and when switching back to closed loop, high positive fuel trims are observed.

07+Silverado Turbo.Layout.xml

07 Latest and Greatest open loop 2019.hpt

19-11-22 06-34-09.hpl

Has anyone used Boost Enrichment> Enable MAP to force open loop as opposed to the conventional ECT Open Loop Table and all the other stuff? "[ECM] 2370 - Boost Fuel Enable MAP: This is the minimum MAP to enable the Boost Enrich table. Additionally, above this MAP the engine will enter open loop." Although the EQ Ratio Vs. MAP Enable MAP minimum table is 105 (which i have set at 1.00), the EQ Ratio Vs. MAP table allows you to set it from 0 to 256Kpa. I switched back to my closed loop tune and then adjusted Boost Fuel Enable MAP from 110 Kpa to 2 Kpa and the truck is in open loop all the time and no longer having the high duty cycle problem. The FSCM is adjusting pressure correctly and as requested.

I used those tables for a second, didn't like them because by the time I was in those boost regions, I would be lean getting into boost fuel since I have an unrealted 4000rpm+ no transient fuel problem.

But, I also get the 99.6% Duty Cycle, but normal fuel pressure. I've determined my 99.6% Duty Cycle reading is fake, that PID gets messed up every time there is an update to HPT. Literally.

So, my question is your rare 1 problem and my rare 2 problems, are they really the same problem just manifesting as two different symptoms?

[mcfarlnd]

Confused by your first sentence. How were you going lean in boost when you were using boost enrichment, seems strange? It works like Power Enrichment but is MAP referenced as opposed to throttle and from my understanding will work with PE and take the richer of the two. I?m talking about using that table to force closed loop ALL the time by inputting 2 Kpa. Doing this has allowed my fuel system to work correctly and my desired and actual psi are almost dead on with a little variance.

I also changed my fuel pressure sensor because I never changed it to match the voltage/ offset in the CTSV FSCM. That alone dropped the pressure to around 89 psi as opposed to the 106 psi previously noted while using the ECT method of OL. Unfortunately, that still puts me over the regulation pressure of the 450 pump and the factory 520kpa regulator in my bucket.

As for the last part, I can verify I am getting high fuel pressures via mechanical gauge and VE. The only way to get higher pressure is to turn up the pump with DC/ Voltage. Secondly, my fuel system status never goes into closed loop using the closed loop ECT table. Mine stays in Open Loop, Cold Engine. It never goes into Low, Normal or High Flow unless I change the ECT for Open loop back to stock. Id be willing to bet your pump is at 99.6% constantly. Curious where your sensor is in relation to your boost a pump? Is your boost a pump going to maintain whatever pressure you want it to regardless of input? Or if you have a return style system, your always gonna see the correct pressure you have mechanically set it at while that pump is at 99.6% DC. I haven?t used a boost a pump nor do I have much experience with one outside of the old mechanical ones. Your FSCM and ECM are programmed different than mine as well (I?m assuming you are not using CTSV parameters). Have you logged fuel system status?

[mcfarlnd]

Another thought, is your pump stock? Is it PWM capable?