2007 N54 335xi Boost Issues

[aporter360]

I have a 2007 335 XI with the typical 30FF underboost code. I have done a thorough inspection of the vacuum system and there are no vacuum leaks. The wastegates close and hold under a vacuum. The rear turbo has almost no rattle and the front turbo only really rattles under a cold start for about a minute then goes away. I just bought this car and the previous owner said it will need new turbos. I have done some investigating into the 30ff code and i know about the wastegate issues where they will wear out and not fully close, as well as the boost solenoid issues and vacuum system issues that could cause the code. I have an accessport tuner and i did some datalogging of the system during a 2nd gear pull, and 3rd gear pull. The system is demanding about 16psi but it can only make about 9psi at max rpm. I have logged and charted the data and will post a picture if i can. My biggest question is that the car is still making boost, but under the most puzzling way. The boost curve is almost perfectly linear which is super strange. I feel like the boost curve should jump up to make boost early on in the rpm range but instead it takes the entire pull to reach its boost and it does so in an incredibly linear fashion even though the load requested and wastegate duty cycles are requesting a flat high load amount. Has anyone seen this or could explain what could be going on mechanically?

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https://drive.google.com/file/d/0B9dtkeJYqoHZUl9wQ0lpeEljOUhTMjQxUGV5NkpORWxnVWRV/view?usp=sharing

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https://drive.google.com/file/d/0B9d...ew?usp=sharing

[pbonsalb]

Have you done a smoke test?

[aporter360]

I have not done that yet but that was the next thing on my list to have done.

[pbonsalb]

You can make one and DIY. Google.

[aporter360]

Ive seen that. i just made one yestersay for about 10$ and will test tomorrow when i have the time.

[pbonsalb]

I just smoke tested my E61 535xi due to a 30ff code. I bought a smoke machine on eBay or amazon earlier this year for about $100 (it has a heater, oil container, uses 12v from the car battery, has a fan to blow the smoke and came with a hose and nozzle and plugs to cap the intake. I found a leak at the front turbo inlet due to a pinched gasket and a leak at the front wastegate because the hose had come off. Retested and all was good.

[aporter360]

Well i smoke tested the engine and i didnt find a single leak. i did find that my oil filler cap was leaking oil and had a slight hissing noise under pressure so i ordered a new one but other than that the engine held about 1 to 2 psi just fine as thats all i could get it to with an air pump and didnt want to blow off the turbo intake as that would be impossible to reattach for the meantime until i get my garage and tools all back. also tested the vacuume lines and they all held a full vacuume just fine. i ran the car on alternate single boost solenoids and the front solenoid had a significant decrease in boost over the rear so i also ordered a replacement boost solenoid to see if that helps at all. we shall see.

[pbonsalb]

You could have a bad solenoid. You could also try tightening your wastegate rods. On my 535xi, it is a royal pain but I did manage a couple of years ago. It just buys some time. I will be replacing my turbos in the next few months though they are working fine now. I use a JB4 and the car has 145k miles and is an 08.

[omarmarji]

check wg solenoid and vanos solenoids