Weird Boost Target Drop

CJKIII

New Member
Jan 12, 2022
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Been sent 7 Revision on my tune and they all have this crazy boost target drop right around 5,500RPM

Checked for boost leaks none found
Checked for vacuum leaks none found
Tuner says its a mechanical issue but i cant seem to find the issue
FBO 17t
Issue arrived about 8-10 days after the turbos were installed.
 

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JohnDaviz

Lieutenant
Jan 6, 2019
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335i E92 DCT
why are you making a new thread? You could have posted it just in the other one. This is not Facebook :D
 

carabuser

Lieutenant
Oct 2, 2019
550
1
410
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UK
Ride
Z4 35i & 335i
You can try logging the torque limit and fuel mode channels to see if there's any clues there. It's certainly not a mechanical issue though.

You should consider just getting a refund from the tuner if he can't figure it out.
 

mj6234

Corporal
Nov 25, 2020
109
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0
I am not sure about it not being a mechanical issue. The rail pressure is in the 700s in the mid range. I would say HPFP is on its way out.

That being said, there are some pretty bad things in that tune. Base WDGC is pretty far off (low) especially near where the drop happens. Boost is over target lower in the RPM range. Load is over requested at 3670 RPM, and PID is trying like mad to reduce boost, but the throttle plate is still at 81 (which makes me wonder if the tuner removed some safeties).

What fuel are you running here? Timing is high, like 11*, I hope it is E50 or higher. I'd be logging timing corrections to look at those ASAP.

What tuner are you using? I mean no disrespect, but I'd be concerned that they dont know what they are doing. I self-tuned my car, and am no expert, but things seem like way off.