2010 MCS (74K miles, auto) - Stock boost?
 

Hi all.
I have seen different numbers on what the stock boost should be. I have a ScanGauge and it shows maybe a maximum of about 9.5psi under heavy acceleration going uphill (not floored, though).

What should I be seeing with it? Just wondering.

I'm also seeing blue smoke after extended idling in traffic (after about 15+ minutes), then it goes away after the traffic starts moving. Read this might be the valve seals. 1qt every 1000 miles (I check and add every weekend and oil changes @ 4K miles)

Thanks.

I bought this car with 53K miles on it. 75K miles now so I decided to replace the plugs this past weekend. I guess they were in bad shape (they looked a bit worn).

Now I get 14.1 PSI! Crazy how a new set of plugs changed things. So smooth now and power! Took all of 18 minutes to replace them. Super easy and cheap. Of course I had to buy that 14-point thin wall socket and a nice torque wrench.

Yeah, the turbo is powered by the exhaust, so a weak burn will result in a weak turbo - double whammy!

So this is goofy. It seemed to work great for about 2 days...now back to lower boost. Perhaps something else is wrong or something is intermittent.

Any ideas?
Thanks.

Maybe a failing wastegate? It could be seating properly at times, but not closing fully at other times. Just a guess......

+1 on the failing wastegate. Mine had intermittent low boost issues accompanied by a "reduced power" light on the tach. After replacing multiple components it ended up being a worn out wastegate. The shaft wears through the exhaust housing causing it to bind.

So the only fix on this is to replace the turbo, correct?

Thanks

Some vendors sell the exhaust housing separately with the attached wastegate assembly. I replaced the whole turbo and oil lines due to high mileage -130K. Remove your pre-cat O2 sensor to observe the wastegate operation using an inspection camera and vacuum pump.

With the engine cold, can I actuate it by hand or would that damage something? Just to see if it's sticky...perhaps actuating it by hand a few times may make it move a bit better?

Just wondering.

Thanks for all of the help!

Maybe, (on a cold engine) remove your heatshields to check the wastegate lever for play. Here a video of mine once removed: