Boost flutter

[DSMtuned]

I was looking at the TIP boost vs TIP boost desired and the TIP boost is much higher and less smooth.  Previous logs show these as relatively close to each other. 

Would that indicate a mechanical overboosting situation?

 

[ajpturbo]

Tip will be all over the place especially if the tuner uses the throttle to help control boost like the oem

 

[DSMtuned]

Tip will be all over the place especially if the tuner uses the throttle to help control boost like the oem

Oh I see.

Well today I took the BOVs apart and checked for tears.  They're good to go.  I also checked for boost leaks by tightening clamps.  All the vacuum hoses look good. 

Reset the KAM and took it for a spin. No better.  Hmm.  Frustrating.  The new boost control and wastegate solenoids should be here in a couple days, so fingers crossed they help.

 

[DSMtuned]

Well it's definitely related to the wastegates. I don't know the cause yet. I'm thinking the tune is not compensating for the decreased backpressure. My tuner is going to look into it.

I almost burned up my GoPro case filming this...

https://youtu.be/xDEsR0Yk3OQ

 

[ajpturbo]

Shouldnt really have anything to do with back pressure.....i want to say your altitude has more to do with it....wastegates can do funny things if the tq is being commanded in a strange way ...its going to be really tough to figure out

 

[ajpturbo]

Im not sure you can accurately blame it on anything at this point until you data log what desired tip is doing when the issue occurs....if desired tip is occilating then its just doing what its supposed to

I have found that high altitudes require alternative methods for torque/boost delivery...the normal mehods are not always the best way

 

[ajpturbo]

I fear you are now starting to throw money at parts without proper justification....i thought you posted a log where desired tip is fluctuating....if thats the case then its likely not a hardware problem....something is telling the hardware to act a certain way

 

[ajpturbo]

Would you like to try a test tune?

 

[SHOdded]

Would you like to try a test tune?

Do it do it do it

 

[ShoBoat]

Curious, have you tried to return the truck to the stock tune and see if the issue persists?

 

[lamrith]

Would you like to try a test tune?

Do it do it do it

C'mon man try it, everyone is doing it....  hahahaaaa  1st sample is free...:smoke:  local neighborhood tune dealer slingin the goods!!

 

[FoMoCoSHO]

Would you like to try a test tune?

Ah, the digital power pimp hard at work, lol.....

 

[8nutz8]

Would you like to try a test tune?

When this is offered you better take the bait! take if from someone who has his tune at your exact altitude! He can work through the issues and get your car running right withing a couple revisions if not less. I may have been one of the test products and i'm damn happy with the results.

 

[DSMtuned]

I fear you are now starting to throw money at parts without proper justification....i thought you posted a log where desired tip is fluctuating....if thats the case then its likely not a hardware problem....something is telling the hardware to act a certain way

Yeah I did throw a wastegate solenoid at it because I found one for $15.  I can't find a copy of the PC/ED so I didn't have the test procedure for the solenoid. 

I'm getting frustrated with the lack of communication from the reputable tuner.

 

[DSMtuned]

Would you like to try a test tune?

Yeah I'd be happy to try one of your tunes!  I'm pulling my trailer across Colorado in a couple weeks and I'm worried my truck won't pull it.

 

[ajpturbo]

Check your PM

 

[DSMtuned]

Curious, have you tried to return the truck to the stock tune and see if the issue persists?

I need to try this.  Honestly, I really dislike the factory calibration and have been less than excited to return to stock. 
My truck has been tuned since a week after I bought it.  . With the downpipe I'll surely to get CELs on the stock tune.

 

[ajpturbo]

You really need to return to stock like mentioned by sho boat

Its really the first step in troubleshooting an issue with a tuned truck....you blindy already threw money at the truck already

You need to isolate and rule things out when possible and returning to stock achieves that

 

[DSMtuned]

You really need to return to stock like mentioned by sho boat

Its really the first step in troubleshooting an issue with a tuned truck....you blindy already threw money at the truck already

You need to isolate and rule things out when possible and returning to stock achieves that

Got it.  I'll do that today.

 

[DSMtuned]

UPDATE--  **FIXED**

AJP turbo was kind enough to build a test tune for me so I could rule out my tuner's calibration as an issue.  After loading his tune, I found the boost oscillation persisted.  This led me to believe the problem was mechanical. 

I had a feeling that the catch can check valves could be an issue because they are simple spring loaded flaps of rubber vs ball valves.  I took the check valves apart and found both to had failed, causing boost leaks! 

Next I built a boost leak tester.  I found a slit in the driver's side wastegate line under the clamp, where I missed it during inspection of the lines.  After fixing this and returning the PVC system to stock until I can get new check valves for the catch can, I took the truck out for a spin.

FIXED!!!!  Unbelievable!  I think it was coincidence that the boost fluctuation coincided with the downpipe install, or I worsened the wastegate line leak during the install. 

So I learned to not forget my roots of tuning DSMs and Subarus and go for a boost leak test right away instead of going down the road of more complicated problems.


Thank you all for brainstorming with me.  It's great to have a community like this to learn from.