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I've tuned a few Zr1s and never ran into an issue like this. The fuel pressure dips at 4k no matter how I have the high flow mode kick in. If I set it before or after where the drop is happening the pressure still drops. I've adjusted just about everything I can think of. Can someone take a look and see if I'm missing something? Bolt on ZR1 making about 700rwhp.
Pump cuts out and builds back up after 4k. Attachment 109930Attachment 109931
I can't open your file (I guess I need to update my HPTuners software); but my first thoughts are: you're either not in High Flow mode, or you need to increase pump duty cycle relative to Flow and voltage.
Your High Flow Upper threshold should be low enough to be triggered before 4K RPM. Your High Flow Lower threshold needs to be less than that, of course. Make sure you're not still in "Normal Flow" mode - which allows for FP modulation and typically accounts for "The Dip."
If those things are correct, then I'd make a ~5% change to the Open Loop Duty Cycle table at the appropriate pressure ranges.
Although the file link shows .hpl as the extension, when you download it, it downloads as .hpt (the actual tune) not as the log. Therefore, it won't open in the scanner, only the editor.
Maybe see if Random84 comments are applicable
https://forum.hptuners.com/showthrea...l=1#post650593
I played both sides of the pressure drop. I had the high flow mode trigger before and after the dip with the same results. I'm positive it engaged as I set it to a certain psi so it was obvious on the scanner. I also raised and lowered the pressure to see if it would help either way. Makes sense to increase the fuel pump voltage in that range to see if it helps. Is that table in the fpcm?
You can change the commanded duty cycle. Mine has been set at 99.5% forever. I have a lean spike upon sudden WOT. I have spoken to some well known tuners and was told there is nothing that can be done about it because the boost comes on so suddenly with a PD blower. It is only noticeable in a data log and has no effect because it is of such short duration. I haven't messed with minimum duty cycle while trying to figure this out.Quote:
Originally Posted by JASON11WS6
Wouldn't leaving the pump at 99.5 dc fry it over time?
Yes, you would think so but mine is not having any issues. If and when I need a new pump, I will probably go to a Fore setup unless I found a good deal on another OEM pump. The OEM ZR1 pump is a beast of a pump though.