Possible Issue from Tune
 

I haven't posted here in a good while, but I have a 2009 HHR SS Auto AA5. I've had it for a couple years and bought it with around 60K, it now has 88K.

It's an automatic and the only mods as of yesterday were, offroad pipe, magnaflow muffler, and KN intake. It drove fine and shifted through each gear at full throttle with zero issues.

Yesterday I took it to a tuner, and had it tuned. It runs excellent through first and second at WOT. However on freeway speeds, getting on it, at around 55-60 mph, it starts out accelerating fine and strong, but then around 5500 rpm or around 80 mph, it acts like it's hitting a rev limiter. It doesn't up shift until you let off and back way out of the throttle, or shift to neutral and then back to overdrive. Even if you let off, it acts like it's hanging in gear until you go to neutral.

It seems like if this was a transmission issue it would have problems between first and second also. As long as you don't get on it, it drives fine. Also you can get on it at higher speeds and as long as it's not floored it seems fine then too. I'm not saying it's the tune per se, just that there were no issues prior to the tune.

I'm open to any advice here. I haven't done a transmission flush or checked fluids and so forth yet. It seems like it may possibly be software related, as there shouldn't be any issues with a rev limiter at 5500 rpm.

Take it back to your tuner.

x2!!!

X3 !!!

Oh what the heck, I'll vote.
X4 !!! :deadhorse:

Do you have a HP Tuners tune installed ?
Fill us in.

Yes I do.

I plan to return it to the tuner. He's just 3 hours away, and he didn't seem to think the issue was related to the tune.

They never do! What else is new, just prior to the tune? Stage 1 GM sensors?

https://cimg0.ibsrv.net/gimg/www.che...c6e484d5b.jpeg

any possibility of loose clamps? Or cracked pipes or tanks on the inter cooler

Do check to see if the a/c line near the intercooler doesn't touch the sensor on the downpipe. Mine had that problem back when I owned a HHR SS with GM tune. It would actually go into Limp mode though.Sometimes the A/C line needs a slight shift in positioning so that it doesn't touch it in WOT.

Or, as the installation instruction say, cut the tab off and mount it backwards.