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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > MHD targeting low boost?



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      11-15-2016, 05:00 PM   #1
YoungBlood
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MHD targeting low boost?

So, I'll start this off by saying I have a small boost leak, or bad wastegates, or diverter valves or someging of that nature, combined with being at 5000ft above sea level, so I'm under boost target by about 2 psi at redline. But spool up-5500 rpms I hit target no problem. My issue is, Im only targeting 16 psi tapering to 14.5, no matter what MHD map I try. Why is my car only targeting 16 psi of boost? I just don't understand why most people are targeting 18 psi on stage 2+ or e25 or e40 maps, and I'm only targeting 16 no matter what
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      11-15-2016, 05:17 PM   #2
siphor1989
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I believe the 7.1 mhd maps are load based so mhd will target whatever boost to meet the requested load. As long as actual load matches requested load then you're good.
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      11-15-2016, 06:23 PM   #3
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Wouldn't you make more power with more psi? I'd much rather make 18 psi then 15-16
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      11-15-2016, 06:24 PM   #4
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Actual Load is lower than requested load on all my logs as well, throughout pulls, what would that indicate?
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      11-16-2016, 12:02 AM   #5
siphor1989
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Quote:
Originally Posted by YoungBlood View Post
Wouldn't you make more power with more psi? I'd much rather make 18 psi then 15-16
Quote:
Originally Posted by YoungBlood View Post
Actual Load is lower than requested load on all my logs as well, throughout pulls, what would that indicate?
In that case I would take a look at your WGDC values and see what they're like. If they're abnormally high, then that would point to a boost leak or worn turbos.

Just an fyi, I'm running the MHD OTS e40 map and the DME also only targets 16.7 psi peak and tapers down to 11 psi at redline. However, I hit requested load from 3k onward to redline.

Do you have a clean 3rd gear datalog? You want to go WOT (without hitting the kick down switch if your AT) from ~2k rpm all the way to redline then shift into 4th and stay WOT for a few secs.

Like this: http://datazap.me/u/raigen18/mhd-e40...15-18-19-24-31
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      11-16-2016, 01:26 AM   #6
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I have a clean 91 stage 2 log, not my e40. Interestingly enough, your boost levels look very close to mine, but my actual load, load req, and target psi are all not syncing up like on yours, and I'm closer to 15.5 psi target throughout with the stage 2+. I had it suggested by a guy who builds a lot of n54's around here that I need an intercooler pretty badly, and he thinks the dme would target more like 17 psi if I had inlets (my wgdc is pretty high in the upper rpms) and an intercooler, with my e85 maps. Sooo looks like those are next on my list. and after talking to more people around here, the only people pushing more than 17 psi, are running meth, or have inlets, e85, and custom tunes. I'm close to 6000 ft of elevation near my work where I've done most of my logs. Also, my 3rd gear pulls look wayyyy better than my 2nd gear pulls, I'm off target boost (15-16psi at redline) by like 3 psi in second, more like 1.5 psi in 3rd.

http://datazap.me/u/youngblood/stage...=0&data=4-5-22
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      11-16-2016, 01:41 AM   #7
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Quote:
Originally Posted by YoungBlood View Post
I have a clean 91 stage 2 log, not my e40. Interestingly enough, your boost levels look very close to mine, but my actual load, load req, and target psi are all not syncing up like on yours, and I'm closer to 15.5 psi target throughout with the stage 2+. I had it suggested by a guy who builds a lot of n54's around here that I need an intercooler pretty badly, and he thinks the dme would target more like 17 psi if I had inlets (my wgdc is pretty high in the upper rpms) and an intercooler, with my e85 maps. Sooo looks like those are next on my list. and after talking to more people around here, the only people pushing more than 17 psi, are running meth, or have inlets, e85, and custom tunes. I'm close to 6000 ft of elevation near my work where I've done most of my logs. Also, my 3rd gear pulls look wayyyy better than my 2nd gear pulls, I'm off target boost (15-16psi at redline) by like 3 psi in second, more like 1.5 psi in 3rd.

http://datazap.me/u/youngblood/stage...=0&data=4-5-22
Are you keeping the gas pedal to the floor throughout the entire pull? It's all over the place in the log you posted. A FMIC is definitely a good idea if you're running stage 2 or E40 maps...

Try resetting adaptations and relog and see if things improve.
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      11-17-2016, 03:49 AM   #8
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Quote:
Originally Posted by siphor1989 View Post
Are you keeping the gas pedal to the floor throughout the entire pull? It's all over the place in the log you posted. A FMIC is definitely a good idea if you're running stage 2 or E40 maps...

Try resetting adaptations and relog and see if things improve.
no, I need to disable the kickdown switch, that's part of the reason for the weird throttle position, the other was I was coming around a corner for an onramp. I'll reset adaptions, disable kickdown, and try to get a few more clean logs
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      11-17-2016, 11:14 AM   #9
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Quote:
Originally Posted by YoungBlood View Post
no, I need to disable the kickdown switch, that's part of the reason for the weird throttle position, the other was I was coming around a corner for an onramp. I'll reset adaptions, disable kickdown, and try to get a few more clean logs
You don't have to disable the kickdown switch. Just have the pedal all the way down just to the point before the kickdown switch.
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