[KingDavidsCourt]

I've been a member on bimmerforums for a while.. but I think I need the help of the specialists

I have a 2009 535xi... I have 128k on it now. I have taken it to BMW twice regarding a 'engine malfunction, reduced power' problem.

first time I went they said they would replace the boost solenoids and hope that would fix the issue. They wanted 800$ for that. I said, no thanks.. came home and changed the boost solenoids. While I was in there, I decided to add a JB4 because thats what any good self respecting n54 owner does.

Low and behold, the light came on again. So I turned my jb4 off and went to another dealer... told them I replaced the boost solenoids as suggested by another dealer and the light is still coming on. They advised me that they'd check it out and let me know. They checked it... nothing definitive... but they could start pulling things apart and see what they find for my first born child and unicorn sweat. They did say they tested the turbos and they are fine, as well as the fuel pump recall.. not an issue. I decided to bring it home and start to look into it myself a little.

I did notice there were a few very brittle vacuum hoses under the hood so i decided to replace the ones I could reach easily. It could just be delusion, but I feel like it responds differently now... but my light still comes on.

One thing I noticed.. is that when the car is cool, cool day outside or car has sat for an extended period... the light doesnt seem to come on until it's warmed up....

So I ask the experts here... what could I possibly look for next?

Thanks in advance!

[AZN54]

Is the reduced power when you're WOT? What fuel? When's the last time you replaced plugs and coils? Need more info.

With the JB4 installed, you can check the codes to see if there is further indication to the reduced power, have you done this yet? Also, clear the codes, log, and submit a thread for review; this can help to narrow down possible issues. As of now, your explanation has limited information and will make it difficult to provide advice or a starting point.

[KingDavidsCourt]

Originally Posted by AZN54

Is the reduced power when you're WOT? What fuel? When's the last time you replaced plugs and coils? Need more info.

With the JB4 installed, you can check the codes to see if there is further indication to the reduced power, have you done this yet? Also, clear the codes, log, and submit a thread for review; this can help to narrow down possible issues. As of now, your explanation has limited information and will make it difficult to provide advice or a starting point.

It actually seems like it's mid range... lower-mid RPMS when it comes up more than WOT. I havents changed coils and plugs, as I was told they were done from the previous owner. I guess that couldnt hurt to do either way.

I'm going to have to read how to check the codes... I installed it.. put it on Stage 4 and havent touched it since lol...

PS: Oops.. I typically get 93 when I can.. but occasionally only can get 91

[Jameshawk101]

Read the codes. Those are gonna tell you a lot about your issue.

[Bullitt1841]

If you have a JB4 now, you can read the specific codes and analyze the logs. Start there or you'll be scratching your head for quite a while.

[Steve @ BMS/Fuel-It!]

Start a thread in the support section. List the codes with descriptions and post a log. That will be the best way to troubleshoot this.