Programmer

My 2008 SS has been feeling a bit slow lately (still quick, but not quite the same pin-you-in-to-the-seat feeling that I remember).

I noticed that I'm seeing a peak of about 9 psi in 1st, 12 psi in 2nd, and 14 psi in 3rd and 4th gear. I remember seeing up to 17 psi in 4th on a recent roadtrip. I'm at sea-level, and it's been cooler and more humid lately, so maybe that's it. I'm also due for my first oil change next week, perhaps that'll bring a little pep back. The engine has been idling just a little rougher as well.

I've heard of people with low boost having loose intercooler piping, but I'm not sure how to check that. I just hate not getting all the potential horsepower I paid for!

INSANE SS

mine is starting to feel the same way!!!! Did you come across any help? Also just noticed that after sitting a day or two on start up mine will puff smoke out the tailpipe not a lot but enough that it can be seen anybody else?

bobiroc

I had a problem like that and when I took it into the dealer because I had a brake issue they also fixed something to fix the performance. Off hand I do not remember what it was but if I get a chance when I get home I will post the information off my repair sheet as it may help.

Lone Ranger

If you're having brake issues, don't rule out the brake booster also for engine issues. When you take into consideration that the brake booster recieves a lot of engine vacuum, and that a small leak in the brake booster can change the manifold pressure that the MAP sensor is seeing it can account for actual engine drivability issues as well as braking issues. A leaky air valve on a brake booster for instance may cause a slight increase in the normal "at rest" contact pressure of the brake pads against the rotors which will cause some brake drag but also cause the MAP sensor to read higher absolute pressure in the manifold and thus this fools the ECM into thinking there is more load on the engine than there is and it can mess up fuel trim or at least cause a tug of war between the injector pulse width being richened due to the spoofed MAP reading and the oxygen sensors seeing unburnt fuel in the exhaust stream and telling the ECM which then attempts to go leaner. If the car has an auto trans the spoofed MAP reading can also effect shifting of the trans. If the booster is only leaking at the air valve on the driver side of the diaphram it would not cause a hard pedal like a vac leak on the firewall side of the diaphram would.

Bottom line: A leaky air valve on the brake booster can cause drivability issues beyond braking and pedal feel.

The good news is HHR brake boosters are cheap, the bad news is you have to remove the electrical center and disconnect a bunch of stuff to change one out. Its a 3 hour job by a pro GM tech, longer by DIY. Because it involves brakes, it is strongly recommended to be done by GM dealer service dept or other professional shop, or at least in strict accordance with the Factory Repair Manual if doing DIY.

TkHHR

After my boss took me for a spin in his Z-06 Corvette... every car feels slow! There is no substitution for shear horsepower.

bobiroc

Ok, here is what the dealership said they fixed when I told them the HHR felt like its performance was decreased

"Ground Circuit per PIP4412 Found Tight. Inspect Vehicle operation/perform bulletin search. Inspect vehicle per PIP4412"

Whatever that means.

robotworkshop

So if you have the HHR back again does it feel faster than when you took it in?

bobiroc

Yes, the acceleration is back to when I first bought it. How I noticed the problem originally is when I was coming down an onramp to the highway and when I punched the gas it did not have the acceleration I was used to. At first I thought it was just a one time thing but then I purposely accelerated faster than normal for about a week to see and I couldn't even chirp the tires when flooring it. That is when I knew something was not right.

When I got it back I tested it over and over and even floored it hard at a stop light when no other cars were around. Tires sqealed in first gear and chirped in 2nd and 3rd (and that is with the traction control on). Much better.

Snoopy

Just kind of wondering out loud (but really in print here).....

If they did some type of electronic/electrical work and disconnected the battery.

People say the ECM would need to go through a relearning process when this happens (kind of like when you install a new intake and are instructed to disconnect the battery for 30 minutes, so the ECM can adjust for the new values....kind of thing).

Lone Ranger

Sounds like they checked electrical groundings and found them okay, and no action was necessary. However, as Snoopy said they likely pulled the negative cable on the battery to do the inspection and thus the ECM is rebuilding the fuel trims.