Can the cruise control be adjusted on a 2007 HHR? Mine reacts too soon and causes the transmission to shift down on any little grade so much that it revs the engine so high it sounds like it's going to blow.

 

That's common if it downshifts while in cruise control... Not every time it downshifts, it depends on how much power it "thinks" it's going to need to maintain speed... Happens often enough for me to say it's "common".

Believe me, the engine's not going to blow when it does this.

 

However, if you had mentioned that when asking about your bad MPG..........

 

Any codes? If not try a battery lobotomy, disconnect the negative battery cable for a full 30 minutes. That’ll reset the computers.

 

I have found that our cruise control is one of the least precise and most quirky ones I have ever had in any car.
Half the time, if I hit the Set button at 75, it will then accelerate up to 77 or 78 before going back down to 75.
On a grade, it will let the speed drop 3 or 4 MPH before dropping into a "passing gear" and getting back up to the set speed.


Also, 45MPH is the worst possible speed limit to have it set at.
It will sit there at 2000 RPM, until you hit a downhill, then it will shift up and go to about 1500 RPM, until the grade goes up slightly, at which point it will downshift again.
GRRRR!

Is it just me? Do the CC modules/circuits or whatever "go bad?"

Would a TB and MAF cleaning help?

 

Don't forget that 4th is overdrive. It goes into 4th around 45MPH, 32MPH if you are just barely accelerating.

Different years seem to have different programming. Not many people are used to driving with overdrive, it is OK to downshift to 3rd, that's the gear you would ordinarily be in driving a 1976 Plymouth.

There is no "adjustment" short of reprogramming (tuning) the ECM/TCM.

 

If anyone wants to search 8-10 year old threads this "issue" was talked to death back then. It's not a "problem with my car" it is what it is. Quirky? Yeah. Is it going to blow up the car? Apparently not...

 

And then there is the "dead spot" when you try to accelerate and have to wait for the torque converter to unlock before it downshifts. Kind of like turbo lag.