Car going into derate

[ACOM]

I have a 2011 135i with a dct, car wont build over 5 psi of boost. Car is running jb4 on map 2 which should be 14.5 lbs of boost. Drove the car home and car ran fine no issues, sat over night and now i have a cel if i go over half throttle. I have already done a smoke test to check for leaks and i didnt find any anywhere. Got a better scan tool to check codes with to try and find out whats making car go into derate. The scanner has functional tests i can do for i believe the wastegate and diverter valve. No clue what exactly they are testing but i cant tell if either test is doing anything. One test car has to be running so i assume thats the wastegate test, so i pop the hood perform the test but wastegate doesnt move. For obvious reasons i cant see the diverter valve moving when testing. Also i was unsure on how to change values on ambient pressure so does that look correct?

[dtla1]

Step 1 for me would be to remove the JB4, clear codes and see what comes back. Sometimes the JB4 is set to autoclear codes so you might not be seeing everything. Also, the JB4 will trigger certain codes that most deem as "Tuner codes" (like the 2c90) so this will eliminate those.

CEL when over half throttle could be a few things, my main guesses would be HPFP, Diverter Valve, or the JB4 acting up.

What other modifications do you have on the car besides JB4? Mileage?

[Dackelone]

The N55 is known to break/crack the charge pipe - going into the throttle body. IF you look under your hood you might see the CP crack or in the very least a buildup of oil spray showing you the area of a boost leak.








IF you are running more boost that "stock" you should replace your charge pipe and blow off valves(recirc valves).


some relevant links...
https://www.e90post.com/forums/showthread.php?t=654263

https://f30.bimmerpost.com/forums/sh....php?t=1407066

[ACOM]

Originally Posted by dtla1

Step 1 for me would be to remove the JB4, clear codes and see what comes back. Sometimes the JB4 is set to autoclear codes so you might not be seeing everything. Also, the JB4 will trigger certain codes that most deem as "Tuner codes" (like the 2c90) so this will eliminate those.

CEL when over half throttle could be a few things, my main guesses would be HPFP, Diverter Valve, or the JB4 acting up.

What other modifications do you have on the car besides JB4? Mileage?

Will eliminate the jb4 and ear then try again, i have a gfb diverter that should be here next week. I can monitor fuel pressure but idk what its supposed to be. Other then jb4 thats really it for mods, short list lol. Milage is 85k right now.

[ACOM]

Originally Posted by Dackelone

The N55 is known to break/crack the charge pipe - going into the throttle body. IF you look under your hood you might see the CP crack or in the very least a buildup of oil spray showing you the area of a boost leak.


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IF you are running more boost that "stock" you should replace your charge pipe and blow off valves(recirc valves).


some relevant links...
https://www.e90post.com/forums/showthread.php?t=654263

https://f30.bimmerpost.com/forums/sh....php?t=1407066

Stock charge pipe has been replaced with another oem charge pipe. I have an aluminum one just havent installed it.

[Dackelone]

You still need to check the codes with the JB4 turned off. See dtla1 comments above. And I would look for a boost leak under the hood. Just bc a part have been replaced doesn't mean it is in good working order. The factory charge pipe fail all the time. Especially on the N55 engines.

[dtla1]

Originally Posted by ACOM

Stock charge pipe has been replaced with another oem charge pipe. I have an aluminum one just havent installed it.

Was the replacement installed recently or semi recently? Could be the big o-ring that goes inside might be missing or got dislodged during install as well.

[ACOM]

Originally Posted by Dackelone

You still need to check the codes with the JB4 turned off. See dtla1 comments above. And I would look for a boost leak under the hood. Just bc a part have been replaced doesn't mean it is in good working order. The factory charge pipe fail all the time. Especially on the N55 engines.

Gonna test this tomorrow when i have scan tool with me. I need to go ahead and install my intake and get rid of the plastic one. I did a smoke test but didnt find anything leaking

[ACOM]

Originally Posted by dtla1

Was the replacement installed recently or semi recently? Could be the big o-ring that goes inside might be missing or got dislodged during install as well.

Was installed i think 4 or 5 months ago. Dealer installed it.

[dtla1]

Originally Posted by ACOM

Was installed i think 4 or 5 months ago. Dealer installed it.

Unfortunately dealer workmanship sometimes isn't as great as one would hope. You said you had an aluminum charge pipe ready to go? Maybe this is your time/excuse to install it. If the o-ring is missing from what i remember it's the same one/size as the bigger o-ring that gets replaced during an oil change (that's seals the filter housing).

[ACOM]

Turns out its the 5 month old jb4. Removed jb4 cleared codes and car runs fine with no cel. Does jb4 have a warranty?

[dtla1]

Originally Posted by ACOM

Turns out its the 5 month old jb4. Removed jb4 cleared codes and car runs fine with no cel. Does jb4 have a warranty?

No clue, I bought might second hand (but still new, never installed) and it fried itself within a year and a half. Your situation might be different, I would contact BMS directly.

[HyeWarrior]

Personal opinion. JB4 is inconsistent and problematic, especially for a daily. Glad I went the MHD route

[dtla1]

Originally Posted by HyeWarrior

Personal opinion. JB4 is inconsistent and problematic, especially for a daily. Glad I went the MHD route

Opinion Seconded.

[dtla1]

Just checked the BMS website, there is a 5 year warranty on the JB4...

[ACOM]

Originally Posted by dtla1

Just checked the BMS website, there is a 5 year warranty on the JB4...

Saw that earlier, just waiting on response to email.

[ACOM]

Started messing with the car today after removing jb4 this past friday. Drove the car around all weekend and it made stock boost and didnt throw any cels. Installed jb4 again and soldered connections for CAN and relocated ground wire. Removed the case for the jb4 and found one of the diodes somehow had a leg that broke off. Soldered that back in place and drove car to test jb4, its back working but i believe something is messed up with the tuner itself. Its now boosting way past its 13.5 target and hitting past 20psi. Still waiting on reply from jb4 on warranty or a solution so im just gonna run jb4 on MAP 4 till problem is resolved.

[dtla1]

I think what you re-soldered inside (the loose leg on one of the diodes) is what allows your JB4 to run the ISO firmware: Instructional photo from that N54 (Tech) forum below.