Within the last week or so I've noticed something odd about the way my HHR SS has been running. It is a 2008 with an automatic that had the factory upgrade kit installed to boost the HP. It has about 75K miles on it now.

At first I noticed that driving down the side streets and around town that the MPG seems much lower than it did before. When I look at the boost/vaccum gauge it seems that there is much more vacuum than there normally was. At times it is closer to -20 when on a side street. I thought at first that maybe my turbo was starting to go but I didn't hear any noises out of the ordinary so I went to hop on the freeway so I could see if the boost was still working. It was but it seems that if I got into it that the boost gauge would jump up to 25 which is higher than I've ever seen it go before so something definitely isn't right. For the moment I've been driving it easy until I get this sorted out.

Since I'm getting boost I was wondering if this sounds like a problem with the bypass valve or the solenoid that controls that. I was thinking about getting the standard non-vented blow off Forge Divertor Valve and then replace the solenoid that controls it. Or, does it seem like it may instead be an issue with the wastegate actuator or solenoid that controls that? If it seems like the actuator or solenoid does anyone have a recommendation for a replacement? Is there something better that works with the factory GM tune or is it best to just get the original replacement from GM?

Robert

 

I think the over boost problem has been the actuator in the past. I'm running the forge, since 25k when the factory one gave up the ghost. I ran the non vented one for a couple years, and I'm am running the atmospheric vented one now. If you have never changed the bypass it is defiantly time...

 

Everything on the turbo is just the same as the day I bought it new back in 2008. That bypass valve has never been changed. From what I've been reading on the forums that new bypass valve from forge works well and is an upgrade I would want to do anyway. I think I'll start by replacing that and the solenoid to see if that clears up the issue. If that doesn't do it then I suppose that points to that actuator rod on the side of the turbo or the solenoid which controls that.

Robert

 

I would start with the wastegate actuator. The rod to the actuator has two nuts on the end of it which can come loose. Over boosting points to the actuator from a mechanical perspective. All newer k04 turbos have a clip around the arm on the WG rod to prevent such, see pic below. If the nuts are tight then I would say its electrical. UNLESS , you recently disconnected the battery which can cause boost to be slightly higher than normal but will eventually settle down after the computer relearns. -20 vaccum does not sound "out of the ordinary" for an auto.

 

Thanks for the suggestions. I'll have a look to make sure the clip is there and that the nuts look like they are still tight. The HHR really hasn't ever seen hard use and the only mod was the dealer installed turbo upgrade kit.

I suppose I should also mention that it also has the extra vacuum pump installed to fix the hard pedal due to low vacuum.

When I saw it spike near 25 I backed off the throttle so I don't know how long it would have kept the higher boost. I'm certainly not complaining about the higher boost but just thought it was odd that I'm seeing that now and wondered what was causing it. Maybe it is finally working the way it should.

I'll find out more as I dig into it.

I've never disconnected the battery before so maybe it would be worth trying that.

 

Some one sneaked into your garage and Trifecta tune it...

 

The new Forge bypass valve showed up yesterday and I was able to install it last night. For now I just used the green spring that was already installed in it. I also disconnected the battery for a while to reset the system.

So far it seems to make a big difference and the HHR is running much better. Seems to be much more responsive as well. I'm going to see how the drive in to work is today and keep an eye on it.

I believe my car has the crimped connections on the turbo upgrade kit and it may be time for me to unwrap those and then solder the connections. I've got plenty of heat shrink tubing on hand so I can cover each wire when I do it and then tape up the bundle once I'm done. I suppose after that is done I should disconnect the battery again to reset it so it can start fresh with the soldered connections.

 

That could explain a lot, solder them. :)

 

And. Check for any signs of contact between the lower Tmap/wiring and the AC compressor housing.
This was a known issue from the earlier years of the GMTU. The red circle is the Tmap. The brass fitting on the AC comp is what can contact it when the engine moves under torque.

 

I have a new air filter on the way too and am going to install that too. I've never looked to see if the lower sensor has been rubbing on the AC and will check for clearance there as well.

As long as the weather is decent this weekend I will try soldering the connections, check the clearance of that lower sensor, and get the new filter installed.

Thanks for the suggestions!