Newbie here,
 

Hello everyone, I just joined, have my 2nd hhr, 1st ss. 2008. Has 191000 miles on it. Went through the whole car, some people do not deserve cars lol. Anyway, I have searched the sites for all of the info on the turbo, and I need some help. I had obd codes p0100, p0101 and p0299. I changed maf sensor, it was unplugged and had no air filter on it. That is good, now when I cleared the codes, and drove it all was fine, no cell. But my vacuum at idle shows 28. When I punch it the gage goes to -3 for boost and I get p0299 again. Does that mean turbo is gone? I do not know what if anything was done on vehicle. When I got it, it had 4 quarts of oil too much, had bad oil leak in back, well 6 valve cover bolts were not even finger tight, oil leak fixed. And had oil / filter changed, put Mobil 1 in, his sticker showed conventional oil was used. So can anyone help please. And thanks

You need to know more about what you're dealing with. Start with a compression test. You can .

Response to compression test
 

It was one of the first things I did. 175 psi in each cylinder. Changed plugs at the same time. After I got the oil out of spark plug tube

Are you sure the extra fluid was oil?
First thing I would look at for P0299 is a leak/crack/loose boost tubing. Then all electrical connections to the MAPs and MAF.

Here is the diagnostic aids from the shop manual, note the emphasis on "high torque clamps".

https://cimg5.ibsrv.net/gimg/www.che...7476b5dc0e.png

Yes was most definitely oil. Leak is fixed, no oil in tube. I will check that out. Thank you very much for the help. I will keep you updated on the progress.

:welcomewagon: to the forums!

That is surprisingly good compression for not using an air filter.

I'm not sure what you're seeing as far as vacuum and boost. At idle, you should be around 19 in hg. This would be the negative number, the bottom part of the gauge. Maximum boost would be around 14 psi, positive number, top part of the gauge. If the ECM is tuned, you may see up to 24 or 25 psi. But you have to floor the pedal to see Maximum boost.

The P0299 is underboost. So what donbrew said to check, focusing first with the parts associated with the bypass valve. The bypass solenoid is mounted on the intake manifold, 3 vacuum lines and an electrical connector. One of the vacuum lines goes to the bypass valve, another to a vacuum tank underneath the intake manifold. I don't recall offhand where the third line goes, I think to the intake manifold itself. Firemangeorge has a photo floating around here that shows how the lines should be.

Also take the 3 screws out of the cover of the bypass valve, check for a broken spring or torn diaphragm.

Here is that pic and explanation. So the third goes to the lower TMAP sensor.

https://www.chevyhhr.net/forums/hhr-...69/#post789297

Ok, I will check that out. At idle I have 28 ish psi of vacuum, when I step on it I go up to -3 below the zero for boost, that is also when I get check engine light for the p0299

Check the inter cooler for cracks. The plastic ends of the cooler are known to fail.
SS owners will bump into curbs when parking and damage the intercooler without realizing it.

I will. Thank you all for the advice and help. Will keep you updated