Help diagnosing my first e30 pulls (UPDATED!)

proboner

Specialist
Sep 13, 2020
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I'm starting down the path of getting my N54 powered Z4 with Pure 600 DD turbos tuned for E30 and frankly have been having nothing but issues! But for now let's focus on the current ones, and those are related to my first data log. I have a tuner, whom I haven't sent the new logs to yet, mainly because I'm already seeing issues in them. I'm quite car literate, but certainly not N54 tuning literate and imagine there are folks on here who can make much faster/smarter analysis than I can.
Data Log

First problem I'm noticing is the rail pressure dropping with RPM. As you can see, it gets into the low 1000s, which I know isn't good. Unfortunately, however, the Z4 doesn't have a low pressure fuel sensor, so I have no clue if it's the LPFP or HPFP causing this. I am curious though, if the rail pressure drop looks the same regardless of if it's an LPFP or HPFP issue? Does my graph point towards it being one or the other? For context, the HPFP is low mileage (I'm guessing less than 20k miles) and I'm running a stage 2 LPFP (with similar mileage).

The other issue is that I'm not hitting my boost targets. Target is 18 but I'm seeing 13psi-15psi across the rev range. I know this may just be a boost leak somewhere in the charge piping, but I wonder if there's anything in the log that would to something specific? The turbos have around 20k miles on them as well, and have never seen over 18psi. Throws no codes.
 

proboner

Specialist
Sep 13, 2020
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Okay, so it's been a bit since my first runs and I've since installed a LPF sensor to monitor the LPFP. I did a datalog last night (https://datazap.me/u/kriswwashburn/high-rpm-issue?log=0&data=16-17) and found a couple problems that I'm hoping others can provide input on:
  1. At 6700rpm rail pressure jumps from ~1700psi to 2700psi but lambda afr also jumps from 11.5 to 15! not good!
    • I certainly felt this weirdness in the moment, but also heard a high pitched hum, almost like an audible vibration at the exact same moment.
  2. The entire goal of installing the LPF sensor was to figure out what is causing the dropping rail pressure, the LPFP or the HPFP. The LP psi is a bit all over the place around the area of (I'm assuming) peak torque, but cleans up a bit at higher rpms and never consistently near or below 50psi... I'm guessing this suggests the LPFP isn't the culprit?
Any thoughts on the cause of the lean condition in point 1? Given the LP psi and rail pressure psi, does it also look to you like the HPFP is the culprit?
 

proboner

Specialist
Sep 13, 2020
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Did you send any logs to your tuner yet? What do they think?
I haven't, mainly because I'm tuning for an e30 map, which this is not e30 and Im not logging all the specific channels he requested. But now I'm concerned about doing another run because it's running so lean up top!
 

carabuser

Lieutenant
Oct 2, 2019
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Looks like fuel is shifting modes up top. Add fuel mode to your log. I wouldn't worry about boost leaks, the wastegates are still conservative.

Send the logs to your tuner, takes a few revisions to get things sorted.
 

proboner

Specialist
Sep 13, 2020
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Looks like fuel is shifting modes up top. Add fuel mode to your log. I wouldn't worry about boost leaks, the wastegates are still conservative.

Send the logs to your tuner, takes a few revisions to get things sorted.
Thanks, really appreciate the feedback! I did end up sending to my tuner, hope you're right on the fuel mode.

Any thoughts on the cause of the low rail pressure? LPFP or HPFP? I'm thinking HPFP but obviously am by no means an N54 expert
 

carabuser

Lieutenant
Oct 2, 2019
858
1
747
0
UK
Ride
Z4 35i & 335i
Thanks, really appreciate the feedback! I did end up sending to my tuner, hope you're right on the fuel mode.

Any thoughts on the cause of the low rail pressure? LPFP or HPFP? I'm thinking HPFP but obviously am by no means an N54 expert
Second log was ok with rail pressure. Don't know why the first one was struggling.