Boost target drops to 0 mid pull

pysical

Sergeant
Jun 16, 2017
471
108
0
Ride
2009 335xi E90
I just got my car back together after some issues. I took it out for a little casual drive. I wanted to see how everything was going to hold up so I did a slow pull just to gradually check things. In 4th gear on the highway giving it just enough throttle to start building boost, it would go up to about 15 and then just dump it all. I only did this twice and recorded it once. I noticed the boost target goes to 0 and wasn't sure if this is something that is mechanically or electronically controlled? Prior to hooking up the reflex my car would idle fine on startup, now it runs a little rough then clears out. I was also not getting any codes but now I get 2 that I can't figure out.

Log: https://datazap.me/u/pysical/boost-cutting-out?log=0&data=3-21

Codes:
2D2E - DME: Throttle-valve angle - intake-manifold vacuum, correlation
2d33 - DME: Absolute-pressure sensor, intake manifold: signal

I feel like it is related to the Reflex but I am not sure and just wanted to check with people here on things to possibly check before I go removing it.

Thanks!

EDIT:
This tune I have used in the past with no issues. Its a bottom mount 6466 single turbo setup on 93.
 
Last edited:

Threetirtyfive

Corporal
Jan 9, 2019
135
68
0
Ride
335i
2D2E will be because of a vacuum leak (inlet manifold vacuum does not correlate properly to pre-butterfly vacuum). Check the boost reference pipe, and all seals on it. 2D33- what MAP sensor is it? What map? Check the MHD 3.5bar is ticked, check it's wired properly if the n20 sensor. Secondly on the log- the throttle position is very odd, open then partially closed, then goes up again just before the boost target drops, but it looks like boost drops because the throttle position closes in response to you releasing the accelerator? I don't really know ST logs well if this is controlled from a MAC solenoid. Did you got WOT for this? If it's not, I need a WOT pull log to tell anything about what's going on.
 

pysical

Sergeant
Jun 16, 2017
471
108
0
Ride
2009 335xi E90
I thought there was some sort of vacuum leak going on but I can't find anything. Since it is ST most of the vacuum is removed. Also, not sure what you mean by boost reference pipe. I am running the stock sensor on the manifold and a 3.5 on the chargepipe. My tune has the 3.5 integration already in it so I don't need to check it on MHD. As far as the log, I didn't do a "pull". I was slowly pressing in on the pedal and i may have came up or down on it I don't remember. I do know I was staying in it until the boost just dropped, then I let off.

I have two new map sensors coming and a new 3.5 harness (mine is melted a little bit). Only because it might fix the problem and I could use them replaced anyways. I also have a smoke tester coming. I will also do a boost leak check but I don't see why that would cause the target to drop to 0.

I really think it may be related to the reflex.
2D2E will be because of a vacuum leak (inlet manifold vacuum does not correlate properly to pre-butterfly vacuum). Check the boost reference pipe, and all seals on it. 2D33- what MAP sensor is it? What map? Check the MHD 3.5bar is ticked, check it's wired properly if the n20 sensor. Secondly on the log- the throttle position is very odd, open then partially closed, then goes up again just before the boost target drops, but it looks like boost drops because the throttle position closes in response to you releasing the accelerator? I don't really know ST logs well if this is controlled from a MAC solenoid. Did you got WOT for this? If it's not, I need a WOT pull log to tell anything about what's going on.
 

Threetirtyfive

Corporal
Jan 9, 2019
135
68
0
Ride
335i
When you back off the throttle, the car is measuring the vac in the inlet manifold vs the charge pipe (eg vac each side of the throttle butterfly) if there's too much of a discrepancy, eg vacuum post butterfly is too low, it throws this code and it's usually due to a leak.
 

pysical

Sergeant
Jun 16, 2017
471
108
0
Ride
2009 335xi E90
Hmm ok. Thats good info. I am going to smoke test and see what I get. Thanks for your help!
When you back off the throttle, the car is measuring the vac in the inlet manifold vs the charge pipe (eg vac each side of the throttle butterfly) if there's too much of a discrepancy, eg vacuum post butterfly is too low, it throws this code and it's usually due to a leak.
 

pysical

Sergeant
Jun 16, 2017
471
108
0
Ride
2009 335xi E90
I MIGHT have maybe found the issue? I was looking around and it looks like one of the banjo bolts to the waste gate has come loose. Loose enough that air could be moving around it. I know this probably isn't vacuum related but I want to say that when the boost drops, it doesn't come out of the BOV. So maybe the mac solenoid is dumping all the boost out of the wastegate?
 

pysical

Sergeant
Jun 16, 2017
471
108
0
Ride
2009 335xi E90
Did a smoke test and found nothing. Smoked the pipe that goes from brake booster to vacuum pump and then smoked the bov line that goes to intake.
 

carabuser

Lieutenant
Oct 2, 2019
646
1
503
0
UK
Ride
Z4 35i & 335i
Your throttle is just closing because boost is over target. I wouldn't be surpised if those codes are triggered by the throttle not being to close enough to control boost.

Whatever is controlling your wastegate position needs looking at.
 

pysical

Sergeant
Jun 16, 2017
471
108
0
Ride
2009 335xi E90
I replaced both the intake and chargepipe map sensors and the codes have not come back. I also think I have found the issue with the boost dropping. I would go test drive my car with the filter put into the inlet (not clamped down). When I get home it is always popped out and just chilling on top of it. Last night I actually clamped it down and I didn't get the boost drop. My thoughts were the turbo is collapsing the inlet. Now my next step is to figure out why the Reflex is not firing the PI injectors.
 

SLOWESTN54

Lieutenant
Feb 9, 2021
827
551
0
22
B.C. Canada
Ride
2007 E92 335i / 2008 E60 535i
I replaced both the intake and chargepipe map sensors and the codes have not come back. I also think I have found the issue with the boost dropping. I would go test drive my car with the filter put into the inlet (not clamped down). When I get home it is always popped out and just chilling on top of it. Last night I actually clamped it down and I didn't get the boost drop. My thoughts were the turbo is collapsing the inlet. Now my next step is to figure out why the Reflex is not firing the PI injecto
Do you have a new log? What @carabuser was saying is correct you were overshooting your boost target causing throttle closures, But also i noticed you never were actually full throttle during that log.
 

SLOWESTN54

Lieutenant
Feb 9, 2021
827
551
0
22
B.C. Canada
Ride
2007 E92 335i / 2008 E60 535i
@SLOWESTN54


My Reflex is not turning on the PI injectors. I did notice a slight whine sound from the turbo when under vacuum. Soon as boost hits 0.0 and higher it goes away.
Are you using Reflex to control boost? Also don't drive your car until you get this sorted your wayyy to lean. And your over boosting bad. I don't think your reflex has been wired in correctly
 

pysical

Sergeant
Jun 16, 2017
471
108
0
Ride
2009 335xi E90
Are you using Reflex to control boost? Also don't drive your car until you get this sorted your wayyy to lean. And your over boosting bad. I don't think your reflex has been wired in correctly
Yeah I am aware of the lean. Map is setup for PI to spray. This isn't my daily so it will sit until I can verify PI is spraying.

Reflex is wired in correctly. It is 3 wires and a power/ground. I went over it multiple times.
 

pysical

Sergeant
Jun 16, 2017
471
108
0
Ride
2009 335xi E90
Here are some pictures of the reflex wiring and my wastegate/mac solenoid setup.

 

pysical

Sergeant
Jun 16, 2017
471
108
0
Ride
2009 335xi E90
I am thinking maybe put some thread tape on the fittings into the mac solenoid for starters.
 

pysical

Sergeant
Jun 16, 2017
471
108
0
Ride
2009 335xi E90
You could probably look at my post history and find out. But I don't want to blast this company as I really like the kit and the owner has been very helpful. If he warranties it that would be awesome. Only thing I am worried about is a long wait time for a replacement. Other option is to pop it off (I say that like its easy on awd) and take it somewhere local to get welded and then get it recoated. After everything I have been through with this car its just something I would like to get completed before the winter so I can put my daily (F10 M5) in the garage since the Pilot Sport 4S tires don't do to well in winter.
 
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