Gravzy

Hello all, I am new to the site and a new HHR SS owner. I picked up a sweet black 2008 SS. The car is a blast to drive but I fell there may be something acting up and hoping someone can point me in the right direction. Before you ask it has not thrown any engine lights and yes I have a scanner being delivered today so I can check for anything saved. But my condition seems to be getting worse. While at highway speeds 70 to 80 MPH the boost gauge rides just below 0 on the vac side. When I let off or decelerate with the peddle more than cruise control it sputters, you can feel it like misfiring but not. If you know what I mean. Under boost with the gauge reading above zero you don't or if its below say 4 Hg on vac side but between 4Hg and zero you can really fell it. Could it be something with the turbo or wastegate or bypass solenoid. Looking for some help if anyone else has come into this problem. Little over 104K bone stock from what I can tell. No Turbo upgrade kit.

Thanks in advance, Gravzy

Cat Man HHR

Under normal conditions you will see no boost as you drive, it will be in a vacuum.
Are you saying you have a backfire ?
I don't see anything to lead me to a turbo problem.
Don't overthink, just give logical info for people to help you.

Gravzy

Thanks for the response. No, no backfire. I understand the normal driving at highway speeds you will not see boost unless WOT. It at cruising speeds. Every time I let off the accelerator (Decelerating) it hitches almost like hitting a puddle. I can hear the BOV wooshing, but its that slight second between when you lift your foot off the gas peddle that it hitches and the BOV is heard it. It is a 5 speed and really only notice it in 5th gear. I have felt in in 4th but normally in that gear cruising you are building boost so it doesn't do it.

After I read this again I think I Overthought it again. I've done a lot of searching for this issue and cannot find one similar. Trying to explain a felling verses something like a CEL code is easier said than done. LOL

Cat Man HHR

What blow off valve are you talking about?
I have a 2010 SS and don't have one.
Do you have an aftermarket part on your car?
Your turbo has a wastegate valve in it and a controlled vacuum switch that operates it.

Reading material:
http://www.hotrod.com/articles/spott...ow-off-valves/

Gravzy

I guess I thought the wastegate acted as both?? I don't believe there is a aftermarket part on the car. I haven't been all over the car since I bought it a month ago but I guess I should look there first if you don't hear a wooshing sound when you let off the throttle in yours. I guess I assumed that when the actuator shut when you decelerated it pushed air back out into the pipe leading from the airbox to equalize pressure in the turbo. I must have my parts wrong. So are you thinking that maybe the bypass switch is sticking or the wastegate diaphragm?

Gravzy

My new scanner should be home when I get there tonight. At least that's what my UPS email says. I will hook it up and see if there are any CEL's saved and report back after that. Like I said it only happens or is noticeable at highway speeds. It still builds boost and doesn't seem like it falls off any. I can see 15psi on the gauge at WOT and hold it there until I let out. Now that I'm thinking about it I do hear the whooshing sound in the morning when I start it up too. The vacuum gauge seems to go up to or just below 0 and it kinda purges there until it starts to warm up and drop. You can hear it whoosh, whoosh, whoosh then it calms down and drops to 20 Hg.

Gravzy

So my scanner came in and I got two saved codes. P0507 and P0128. Ill search this site to see what the recommended cures are for them.

firemangeorge

P0128= 98% of the time this code means you have a bad thermostat. Not allowing the car to warm up within the acceptable time parameter.

An FYI. Our car's have a BPV (bypass valve) not a BOV. They also do have a wastegate.

Gravzy

Thank you firemangeorge. Yes I thought I knew my lingo yesterday but I was very quickly corrected. On the P0128. I will be changing the thermostat. Is there a post that explains how to on our cars? Is it different then the 2.2 or 2.4? Also do you have any experience with the P0507? I've read a couple on here that its a cleaning thing of the throttle body plate helps but also the MAF sensor. Could the MAF sensor being dirty and possibly the throttle body give me the felling I explained in my original post? Or in your opinion should I be looking for a vacuum leak for both issues, the P0507 and the hitching when lifting off the gas peddle?

Gravzy

I can record live data with the scanner I got. Is there something I should be looking for when it does the hitching motions that might help me pin point or focus on fixing the two codes and see if that fixes the hiccup?