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The turbo on my W450 was leaking badly so I had it replaced. Right before replacement I checked boost and found absolute pressure to be around 1.1 bar @1400 RPM and rising basically linearly to ~1.8 bar @2200 RPM.

 

After replacement I have measured the intake pressure to be 1.1 bar @1800 RPM rising to 1.9 bar @2700 RPM. In other words, huge difference in spool time that affects driveability.

 

Is there anything that can be done to make this cheap replacement turbo spool faster, short of pulling it and replacing it with a genuine part? I'm not familiar with the wastegate. Can it be adjusted to compensate?

 

 

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Generally if you try you will end up with safe mode and a 3k rev limit. If it works then leave it alone seems to be the way to do it.

If you decide to play then do mark the original position because it can be a real dog to get right.

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Playing with the wastegate is easy to do, you simply move nuts to the left if memory serves me correct to increase wastegate pressure that increases to 15.6 psi to be safe . if you go much higher for any length of time it will go into limp mode. it only takes seconds to go too long....but some set it at 17 psi and watch it religously, too much trouble for daily driving imho. to each their own as usual.

As far as I know about turbos is if they spin freely with your fingers and the fins are good that it should be ok....

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As a side note, does your car smoke when the accelerator is applied..?   Just curious....?  If the turbo isn't pushing enough air to fuel ratio , it would be over fueling and this smoke, no?

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  • 3 weeks later...

Thanks for the suggestions, I will try. This turbo has now started squealing, so it may come out of there sooner rather than later.

 

The car doesn't smoke at all. My assumption is that the computer is limiting fuel to match available air, ie, maintain an acceptable A/F ratio. It is certainly gutless, even by this car's standard.

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Question...?  Will the car rev past 3000 rpms or has it gone into limp mode...?  If in limp mode it can't pull the skin off a dead , well you fill in the rest...lol.  Is the turbo getting oil or has the oil feed been compromised? 
I haven't played with replacing just the turbo or just the fins etc as a cartridge...?  They say it's not as easy as you would think.....? I have replaced the entire manifold etc with a brand new unit from Alli-express....it was cheap back then and now isn't offered as a complete unit I don't think...?  Also the parts are expensive.  

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  • 2 months later...

In all my experiences with Chinese turbos, they all spool significantly slower than the OEM turbo.

 

The max psi is dependent on your rpm and load. In my experiences, tightening the nut will allow the wastegate to stay shut longer allowing you to build boost faster, but then you run the risk of overboost. I'm not sure of the exact numbers, but overboost will set if you go over 18psi for 5secs. Once overboost is set, you will lose power and cannot rev past 3k - you can cycle the ignition to reset. Overboost doesn't always get a CEL.

 

Adjusting the wastegate on these Chinese turbos will not solve your slow spooling issue....the turbo lag will become more pronounce and you will constantly set overboost limp mode. On a flat road, it will allow you to be quicker, but then as soon as you hit a steep hill, or downshift to pass on the highway, you will go into limp mode when you need power the most.

 

My 2 cent.

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  • 3 weeks later...

Word to the wise, the cheap knock off turbo's are not worth it.... that's not the part to go "budget" on. Maybe someone can post a link to their latest "good" purchase. It's changed over the years probably. I last saw a turbo cartridge going into a car I owned after I passed it along when I'd done a 2000 km test drive to ensure it was a worthy candidate to be refurbished - but that was I think 2018.....!

 

I will get to see if P0238 triggers in my current smart again since the EGR has been cleaned up and a brand new intercooler installed. Turbo not touched, and my car was not rev limited! The turbo *sounds" really good... very nice spool-up. So we'll see.....

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