Powertrain strange behavior (underboost + overboost)

[wattaman]

I have some strange issues with my car (Hyundai Tucson Gsi Crtd 2Wd A, 2l engine, diesel, 2007, 76000m). When starting from cold, it gets a p0299 (underboost) error, MIL and limp mode. This happens soon after the car starts moving, but not when stationary on idle.
The limp limits the rmp to 3000, so I reset the error codes while driving, using a mobile app. If I do this before the engine gets hot, the error happens again, MIL, limp etc. However, if I drive until the engine gets hot and then erase the error code, it drives fine and this does not appear anymore (until next morning).
But if - after deleting the p0299 while driving - I force the car too much (drive uphill, speed faster), then there is a p0234 code (overboost) logged. This does not cause the MIL, and it does not seem to limit the revs. And if I don't delete this error, then next morning I have 2 errors logged, underboost and overboost.

I've also attached a freeze frame that says nothing to me because I'm not a specialist. What I basically do is follow other people 'how to' tutorials - so far I haven't manage to blow up the car
Some things I've done: replaced the boost pressure sensor, cleaned the turbo (hot) & DPF with Mr Muscle, sprayed Revive and then Vetech dpf fluid into the air intake (should have cleaned everything), replaced the EGR valve and fixed a boost leak (EGR cooler), changed to better diesel and used various additives, changed engine oil, checked the wastegate actuator.
After all this, power is much better, except for the problem described.
Can it be anything else except for the turbo itself?

 

[baldykev]

might be worth checking if your turbo is a variable vain unit. If so the variable vains my be sticking only way to clean check is to remove turbo and visaul inspection.

 

[sxturbo]

It's the variable vanes in the turbo, they are common to gum up, when it's hot the carbon loosens up and the vanes become free.

You can buy cleaning fluid to remove the carbon deposit. I'm not sure Mr muscle is really strong enough to do the required job.

Also the vanes do wear over time, and it may just be the hinges are worn

I've had mechanics have some success with this https://www.ebay.co.uk/itm/Diesel-E...2349624.m46890.l49286&mkrid=710-127635-2958-0


Otherwise it's likely a new turbo.

It could be the actuator playing up, but can't remember if they are mechanical or electronic actuators on these

 

[wattaman]

It's the variable vanes in the turbo, they are common to gum up, when it's hot the carbon loosens up and the vanes become free.

You can buy cleaning fluid to remove the carbon deposit. I'm not sure Mr muscle is really strong enough to do the required job.

Also the vanes do wear over time, and it may just be the hinges are worn

I've had mechanics have some success with this https://www.ebay.co.uk/itm/Diesel-E...2349624.m46890.l49286&mkrid=710-127635-2958-0


Otherwise it's likely a new turbo.

It could be the actuator playing up, but can't remember if they are mechanical or electronic actuators on these

Thank for the suggestion.
I've tried to find how to use the Diesel Turbo Cleaner Kit, but there's not much about them on Youtube. I'm afraid those sprays must be injected directly into the turbo, not in the air intake (as I've seen Wynn's does - without any effect though). If this is the case, I'm gonna give Mr Muscle another try because first time I only let it 2 hours To do its magic.
I only need another sunny day in Scotland and it looks like it won't happen any time soon.

 

[wattaman]

Yeap, I've just read the reviews on Amazon. You need to get to the hot side of the turbo, meaning I have to crawl under the car again and remove the exhaust.

 

[baldykev]

look for a turbo cleaner made by Forte ,mate had a problem with his turbo Vains on his VW golf (put into fuel tank) it did work.
try a couple of cans
Good luck