Boost oscillation

Hello,

I am wondering if anyone has seen a boost oscillation problem such as this:

(3rd gear log)

There is no vacuum leak that I can see from smoke test, and it is definitely not a tune issue as a different tune map also result in basically the exact same problem. And both tunes was done ages ago which was perfectly fine then. And actually, it was better last week when I logged it but not perfectly smooth either.


Please help.

 

Can you please post the log file?

I am not a guru, but I wonder if it's the factory electronic boost control solenoid being stupid.

 

Hello,

Yes sure.

Here is the log as posted on screenshot uploaded to datazap: https://datazap.me/u/daniel-lheman/bbr-gti-2?log=0&data=4-7

The log I posted above is not the map I am using at the moment as I was just trying to test if the same problem exists when using a different tune, which it does.

Here is the log of the map which I currently use. The boost looks exactly the same (should not be).
https://datazap.me/u/daniel-lheman/moto6?log=0&data=4-7

I didn't noticed this problem until I started to log the car again. The car is 2011 model, FWD with automatic transmission. There is no indication of this problem when driving normally, or driving it fast either in manual or automatic mode. Everything feels normal except when doing datalog.

 

automatic? what are you driving?

 

CX-7, EB.

 

Well, I guess I may as well change the EBCS to 3 port and run on 2 port to see if it fix the issue.

Which plug and play 3 port EBCS is recommended?

 

Would help if I looked at what section I was in. I also forgot these existed for a min

 

Grimspeed, Cobb, JBR, all have ones that are plug and play, also just a simple 3port Mac ebcs that you could make yourself if you really wanted. You may have so search for a Mazdaspeed 3 or 6 one of you're looking for 3 ports, connector was the same on earlier models of the cx7 don't know about the 2011 https://mazdaspeeds.org/index.php?threads/how-to-diy-an-ebcs.10919/

Probably a few of us that did

 

Hmmm, the part number for the oem boost solenoid is the same for all year model of Mazdaspeed3/6 and CX-7.


Then again, a friend of mine fitted his CX-7 with Corksport EBCS and it fits. So I think there is no change in connector style between the models and model years.


Since we can rule out the tuning, other than EBCS what could be the issue?

 

Boost is not controlled, so that seems the best place to start. Be careful removing the hoses from the factory ebcs, they can be brittle. Get some fresh hose at auto zone.

 

Alright I placed an order for GS 3-ports EBCS. I quite like the idea of placing it farther away from scorching heat.

But yeah, it is a very strange problem because the car drives nice and makes good boost. Then again I am always above 3000rpm whenever I want to WOT. Hopefully this sorts it out because I do have an interest in going for CS intake manifold and run Aquamist direct port WMI.

 

Alright, so while I wait for the GS EBCS I decided to do easy stuff of checking and cleaning the sensors which are accessible.

1. Cleaned the MAF sensor.
2. Tighten every clamps.
   
3. Cleaned the throttle body.
4. Cleaned the MAP sensor.
5. Founded out the hose between head and intake was torn and fixed that.
6. Double check the corksport catch can is in full closed position.

On the first cold start after removing battery, as part of the throttle body learning, after 10 mins of idle the STFT settles down to 0.00 (it was +0.07 before, which must be from the torn hose) and likewise the LTFT is at 0.00 also. The boost oscillation issue is still there, but at least I can rule out the MAF, MAP, throttle body and vacuum leaks.

Speaking about accessible; damn this is a big car with not much space around the engine bay. I do not know if there are any difference in wiring loom, but it does looks a whole lot easier on MS3 than CX-7 to remove the MAP sensor. I think I was able to remove it by sheer will because I can't quite recall how I did it other than going through some tight spaces with some small ratchets. And I thought working on WRX STI is bad, this seems to be even harder!

 

I finally received the GS 3 ports EBCS, and it doesn’t solved the problem. I’m running it on 2 ports of course.

A few things I noticed while replacing the EBCS:

1. There is no restrictor pill on the hoses between the IWG and EBCS, and between EBCS and turbo inlet. I mention this because I thought there is a restrictor pill. Well, maybe the restrictor pill is between turbo and IWG actuator.
   
2. I spotted oil leak coming out of the turbo outlet. I do have CS catch can, so I guess the oil seal in the turbo is busted.
3. The OEM ebcs port to the inlet got some residue. I guess the oil came from the turbo outlet hose which connects to the IWG actuator, and made its way to the EBCS.
   
4. The oem EBCS hose coming out of the IWG actuator is pretty stiff and got micro crack. I can actually snap it into two cleanly as I was trying to see if there is a restrictor pill or not.

Well, I guess I’ll just use the OEM EBCS again for now, with new hoses obviously. Maybe the IWG diaphragm is busted due to the turbo’s broken oil seal.

Damn it.