Anyone have experience with the Dorch 2.5 on N55 car? I just upgraded from a Dorch stage 1 and notice the rail pressure is oscillating and getting out of control. I flashed my custom tune with the settings for Dorch stage 2, as Dorch tech support advised. I didn't have the oscillations at this exact power level with my DS1. Guessing settings for HPFP control need updating in the tune. I am still on the stock 2015 535i xdrive LPFP and think I would have had this problem on DS1 if LPFP was having trouble. Thank you for any advice.
Dorch 2.5 HPFP rail pressure oscillations on 2015 535i xdrive (updated with 10.93@124 quarter mile video)
- Thread starter mikesrex
- Start date
Wow, I didn't know they had a stage 2.5, just googled it, awesome! Did you send Dorch your bin? I believe they'll update the pump parameters for you. I've got the stage 2, but haven't installed it yet.
I suspect that 2.5 just needs slightly different parameters to run just right. Suprised they didn't mention stage 2.5 specific parameters? Hopefully the mhd app will get updated with that as an option.
In their note they said the parameters for stage 2 should work for 2.5. Here’s their note:
Hi Mike,
Long ago we updated all of our HPFP mapping so that DS2/DS25 and DS1/DS15 operate on the same pair of calibration files. So even though it may still just say “Stage 2” in the MHD app, this file works perfectly for DS2 or DS25. Your log shows perfect HPFP operation and you are only utilizing a peak of about 65% of the HPFP’s total capacity and this is only at low RPM. Up top you’re only utilizing about 38% of the HPFP capacity. Keep in mind that this HPFP outflows your OEM LPFP, so if you start to push the car a lot harder on E85 you will need to upgrade the LPFP not only to make the power number, but to also keep the HPFP safe. Meaning, you don’t ever want to push past the limits of the LPFP in the car as that puts the rest of the system (HPFP and injectors) at risk via running “dry”.
Hi Mike,
Long ago we updated all of our HPFP mapping so that DS2/DS25 and DS1/DS15 operate on the same pair of calibration files. So even though it may still just say “Stage 2” in the MHD app, this file works perfectly for DS2 or DS25. Your log shows perfect HPFP operation and you are only utilizing a peak of about 65% of the HPFP’s total capacity and this is only at low RPM. Up top you’re only utilizing about 38% of the HPFP capacity. Keep in mind that this HPFP outflows your OEM LPFP, so if you start to push the car a lot harder on E85 you will need to upgrade the LPFP not only to make the power number, but to also keep the HPFP safe. Meaning, you don’t ever want to push past the limits of the LPFP in the car as that puts the rest of the system (HPFP and injectors) at risk via running “dry”.
This is the specific log i sent them
Looks like the 2.5 has a little more capability than the 2. I was not making target rail pressure at low rpm when launching my car and decided to upgrade from stage 1 to 2.5. My car would only see the deficient rail pressure on launch during a quarter mile run, since the rest of the run was not at this low rpm. It was not low enough to cause the engine to misfire but still concerned me. I am most likely going to upgrade to a slightly bigger turbo and figure the 2.5 would not hurt. Trying to see what i can run on the stock turbo before upgrading. So far my best run is 11.9@114 in my 2015 535i xdrive. Would like to pick up a few mph and get deeper in the 11s on stock turbo.
Intersting. When I bought my Stage 2 last fall the mhd app only had Dorch or XDI for options (no stage 1 or 2). They told me those parameters worked equally well for stage 1 or 2. However they've since updated for stage 1 or 2, so there must have been opportunity for optimization. I bet it's the same with the new stage 1.5 and 2.5 - probably some opportunity to optimize, but they haven't yet?
Looking at Pure stage 2 Pure 500. Goal is to have decent spool so i don’t fall out of my power band. Also don’t want to need to build a motor or transmission.
Three more logs. One of them has the rail pressure holding above set point into the car shifts.
Update - having a hard time getting any information from my tuner, so i decided to try different HPFP settings using MHD. First try was Dorch stage 1, and the oscillations disappeared. Guessing the gain is a bit too much with the DS2 settings, or something is weird with my specific car. Car runs good, and i think I’m close to its potential on the stock turbo. Next step for me is to probably begin learning the MHD XDF and bin enough to where i feel comfortable enough tuning the car myself. I’m not happy with waiting over a week to figure out how to fix an issue with a remote tuner. If anyone has any feedback on learning the MHD XDF and bin, please let me know.
Are you 98g0b or 9e60b? I'm in the same boat, about to start self tuning for a big turbo. Been reading a lot for a few years but haven't actually jumped in yet.
EWG. Just got back home from the drag strip. Need to launch harder but managed to get my 11 second time slip.
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Nice! That's a good 60ft, my quickest so far on 93 is 1.84 - just draggy, haven't taken the X1 to a strip. What transmission do you have?
8hp45 running Rod Sutphin custom tune. The crazy thing is I’ve been launching in second thinking the car runs better……. Which is correct if i let the car shift in D or S. I was thinking i was finished for the night after running several 12.0 passes and saw my buddy get in line to race, so i decided to go one more time. My transmission temp was a little high, and i know there was a chance the cars might not let me launch in 2nd. I launched in M1 and manually shifted this run to get the 11.90. Next time I’m out i will try M2 launch and manually shift. The dragy doesn’t show delays during shifts, so not sure a M2 launch will help. I did not launch hard in M1 either, but the turbo spools up so fast it probably doesn’t matter.
It will be intersting to see how your M2 launch will compare to the M1 launch. I wonder why the faster time on manual shifting, are you short shifting a bit to keep in the turbos power range better? On my stock PWG turbo, it runs out of breath so hard I feel like running to the 6750 rpm or whatever the srock shift point is slows me down because it keeps the rpms above the tiny turbo's peak power range. I think I'd be faster manual shifting sooner, or adjusted xhp to shift sooner. But I never bothered to play with the shift points.
Still no traction issues in 1st with x-drive, e50 and that 8hp? I'm wondering at what power level x-drive will start to break the tires loose.
