[mindless]

Today's Topic

Turbo Actuator/Sticky Wastegate Problems. My experience with it and how can you fix it yourself if you have the same problem as me

Tools you will need

10mm socket (duhh), T15, T20 and T30 Bits

KCAN to ODB2 Cable/Adapter

ISTAD or any other program that can scan BMW's well

TestO for logging and collecting data to see fruit of your labor before and after

All files needed to log E90 on testO are added at the bottom of this post including where to download TestO

My car info

Model: 3 Series E90'LCI Sedan 2011

Engine: N47TU (Technical Update - Supposedly Fixed Timing Chain Problem)

Mileage: 146 000 Km

Turbo: I am not sure about the brand, but here is a picture of it


Programs Used for Diagnosis/Testing

TestO and ISTAD

All data in my graphs below is collected by using TestO program which requires KCAN cable for your E90.

Symptoms

Let's start off with what codes I have gotten:

(Ignore IHKA, CIC and 4AFA, those are irrelevant)

Code 4521 is the one that will make 1/2 Engine Light Warning appear on your cars display.

Symptoms include lack of boost, no power under 3k RPM and engine going into limp mode straight after 1/2 engine light appears.

How did I figure out what was wrong with my car ?

Well first of all I did not notice any problems until 1/2 engine light warning came on, than I was like, well fuck.

After firing up ISTAD and scanning the car I noticed that I have all of these error codes, and they all had 2 things in common. All of them were pressure related and second, all of them occured around the same time.

So after that I started browsing The Internet and trying to find out of anyone else had the same problem. After days of research I concluded that it could only be 3 things:

A: Wastegate Pin is stuck/Sticky (On Wastegate side not actuator)
B: Wastegate Actuator is not getting any PWM signal/ground problem
C: Wastegate Actuator Pin motor is fucked

So after this I realized that I will need more information to find out the root of the issue, and what is best way to do it without getting your hands dirty? Welp, it's by logging data. So I looked up few tutorials, downloaded TestO, spent couple days figuring out why TF TestO doesn't have E90 N47 files preinstalled by default (I will add links to N47 engine files that TestO needs at the end, but you can also find them in your EDIABIAS folder) and than I started logging different parameters. I have taken multiple hours of logging but here are 2 graphs for you

Turbo Boost - Before Fixing


Wastegate Actuator Position - Before Fixing


Analyzation of Data Above

So let's analyze a bit, but first let me explain the parameters that we're seeing:

Target Boost - Amount of pressure requested by the car's ECU
Delivered Boost - Amount of pressure delivered by turbo to the engine

Real % - Wastegate realtime position/How much is it open (95% = closed while 10% = open)
Req. % - Requested Wastegate Position by car's ECU

Sp, after clearing up any confusion that might occur by just looking at the graphs them selves, what does it all mean?

So first of all, data of both graphs are taken at the same time so you can compare them side to side.

As we see Real % is always at 95% which is closed, and if wastegate is closed that means that turbo can build too much pressure, which is supported by our other graph where you can see that delivered boost is first always higher than req. boost (I have more data supporting this, but this is just a small snippet of it), but not only that it's higher, but it's also above 3 bars which is a no no for N47's lifetime expectancy. But you can see that delivered boost is only higher than req. boost until it's not, and that is because of engine going into limp mode after my ECU renews the 4521 error.

So what's next? Well it time to open the car up and see if it's the actuator issue or wastegate issue.

Popping the hood



So, all you need to do here is to take off front air intake which is held by 3 x T15 screws, Engine top cover which is held by nothing really, just unscrew Oil cap and take it off, you might feel some resistance, but just wiggle it out of its room and it will pop off. And last take off your air filter housing, I do that by taking 2 x10mm bolts off that are located on the left side of the air filter housing, and than 2 x T30 screws which are located on the right side of air filter housing, those are 2 screws that hold your air intake tube that goes downwards to the engine, once you unscrew those 2, you wiggle the tube out of the airfilter and than remove the air filter housing. Once you done done that you should be able to access your wastegate actuator pretty easily.

Wastegate Actuator




So a little bit of an explanation.

Blue Circle is the pin coming from the wastegate actuator which can rotate up and down by 15 degrees (I am not sure if it's 15 degrees, but point is being, it doesn't move a lot by default)

Blue Circle is the pin attached to your Wastegate which controls how much it's open or closed.

Now between those 2 pins should be an arm/lever which connects them together letting actuator pin control Wastegate pin, but you see... while trying to test it by moving it, I managed to brake it... That's why on Wastegate pin you can see small amount of black plastic, which is remainder of the arm.

So how did I brake the arm? Well you see to test if its the pin from actuator that is stuck/not working or if its wastegate itself that is broken I needed to take the arm off so I can move both of the pins independently from each other. To take the arm off all you need to do is to remove locking clip off each pin and than just slide the arm off, well what I did was remove the clip only on actuator side and not wastegate side and than tried removing the pin, which led into it being broken off by too much leverage.

Anyways, with the arm removed I can test these 2 pins individually, first, here a graph from actuator pin moving alone without wastegate connected to it:


As we can see above, wastegate actuator is working perfectly fine by it self, now, lets try to move wastegate pin by it self, here's the video off it:

https://youtube.com/shorts/XeuKbJKen2Y?feature=share

As you can see in the video above, pin that is attached to wastegate actuator is very hard to move, I had to use some sort of leverage, like my extender to move it, it was not possible to move it by hand. So what now? We found out what the problem, now how do we go around fixing it?

Fixing The Issue

So we have pinpointed that wastegate pin is the issue and not the actuator it self, now how do we fix it? Well, while others might just say "Nah man, there is nothing to do, time for new turbo (on my turbo wastegate is internal so I don't have an option to change it out separately)". But no, for me, I wasn't ready to give up just yet, there has to be a way to fix it right? Well with enough WD40 and some other random shit spray that I found at my auto store I thought I give a try. I got a wire brush, start brushing the pin with it while spraying it with WD40 and couple other stuff to remove rust and other compounds that are making it stuck, very important step is to keep moving them pin while doing it so you get it unstuck completely, and after like 20 min, I did it . It went from being dead stuck, to being sticky, but I was able to move it with my fingers without extra leverage

But wait... I broke my the lever connecting actuator and wastegate off... How am I supposed to make it work now? Well me being not completely brain dead, I came up with a simple solution, I 3D printed a new arm since last one was also from plastic, here is a picture of it:



I saw some people were actually selling these arms on ebay for 100 euros, but only for B47 engine, but dimensions are not exactly the same, but close enough.

Results

So, now we fixed the problem, lets test it out!

Here is a graph of wastegate actuator in action:


Here is a graph of turbo boost:


As we can see, its looking much better than previously, now my main problem is fixed, no more engine codes, and no more problems while driving really, not that I notice, but graph does, as you can see there are small imperfections here and there, and these can be blamed on my 3D printed arm not being exact correct length and wastegate pin still being sticky, but I was monitoring live data while driving after fixing it and it seemed good live, so I am happy with my results . Now as promised, here are a few links to get you started with TestO

TestO Setup

Setup and Links off TestO:

TestO Custom Jobs:

How my custom job parameters are looking like:


Files that you will need for all N47 engine types to work on TestO:

E89X.prg: https://mega.nz/file/FftnyC7S#L2XgEg...fo5yEjvaQK8X4c

e90.prg: https://mega.nz/file/FftnyC7S#L2XgEg...fo5yEjvaQK8X4c

Once again, you can find these files in your EDIABIAS or INPA folders under /ECU

Once you have these 2 files, put these on under /ECU in your testO folder, and write in both file names without .prg inside jobs/eculist.txt

Once you done all of that your engine will show up on TestO.

I hope I helped all of you who have the same problem as I did, good luck

[mindless]

Fixed graphs that did not show up orginally

[juiced353]

I created an account just to thank you for this very informative thread - well done bud

[Karlsson_]

Just wonderful! Will try this out and hope it works.

Can you send the 3d print file if my control arm breaks as well?

[jayrich111]

I will be replacing the actuator on my 2015 X3 28D soon and noticed that the linkage/arm is missing. Only a small piece is left on the pin.

Would you be able to share the 3D file or dimensions of the linkage? I have access to 3D modeling software and 3D printers and would love to give this a try before buying a (expensive) replacement.

PS. very informative and detailed post!

Thanks!