Hhr idle mystery
 

I have a 2009 manual transmission hhr with what seems to be an unsolvable problem. I live in Detroit wvuch as you can imagine gets very cold. As the temperature drops, my car gets harder and harder to start. When the car turns on for the first time in hours (say overnight), the rpms will bob up and down dramatically for about 4 times and then sit where it is supposed to. Now that it is December, I have to keep my foot on the gas a little bit to have it even start without dying on me. To make things even weirder, throughout the year, not just Summer, the rpms will sit a little low at idle after about a minute of driving... If I sit at idle for too long, the CEL will come on, but then disappear the next day.... I am desperate for an answer so any help I can get would be great.

:welcome8: aboard!

Step #1 is to head to your local auto parts store and have them pull the codes.

Step #2 is to post up the code/codes here so we can see what is setting the CEL.

A couple of educated guesses, and they're just that without the OBD II trouble codes, are a gummed up throttle body and/or a gummed up MAF sensor or loose connection on the same.

Welcome to the site. :thumb:

X2 on what 843de stated above.
Plus. If you could post the engine size and mileage on your HHR it would help us give you better info.

Fwiw. Any time a CEL comes on, it means the computer has detected readings that are not within proper operating range. Just because the CEL "went out" does not mean it's fixed itself. Most times that CEL code will remain stored in the computer memory for a certain amount of time or key cycles.

Get the code numbers(ex. P0001, P0002 ) . Don't worry about the code descriptions because they have been known to be inaccurate at times. Descriptions are usually just a generic reading.

MAF was the first thing that came to my mind, then dirty throttle body.

Welcome to the site! please post the codes and we can go from there!! cold? only? I agree with the TB and MAF sensor theory but would also check the battery with a load test!

From time to time my RPMs would go up and down and I can feel the engine shake the car. This only happens during idle and this started during the summer time. My HHR is easy to start no matter what the temp is. I took it to my shop and the guy told me that it could be the coils going out on it and that its a common problem with our Ecotechs.

Coil pack on an 06 is different than the single coils on an 09 and would throw a code

You beat me to it Oldblue!:thumb:

The mechanical and electrical differences between the '06 models and the subsequent production years renders them as "Stand-alone" models.

Wow thank you guys so much. I am so happy to be getting some help finally! I've been so stumped. I've got a little over 68k on the HHR and as far as the engine code... I can't remember the exact code but I believe it pulled "Rich Fuel Bank #1"

Adam. Reread the posted answers above. As we stated, you'll need to post up the actually CEL code number for us to try and help.
Code descriptions don't really mean much. They are very often inaccurate and can point you in the wrong direction for the fix.

x2 - plus as he mentioned, we need to know what engine and mileage.

Apologies everyone. The code number is p0172. Also the engine is 2.0L 4 cylinder. Manual transmission. I hope this is the information needed to assist!

Only the SS has a 2.0 turbo engine. The regular HHR's have either a 2.2 or 2.4.
And how about the mileage on your's ?

OK then, the actual OBD II trouble code is a P0172, much more helpful...although the mileage on your HHR is also a tidbit of info that may help narrow down the problem.

But let's look at what a P0172 code means....

It may mean that one or more of the following has happened:

* The MAF (Mass Air Flow) Sensor is dirty or faulty.
(Note: The use of "oiled" air filters can cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry)

* There could be a vacuum leak.

* There could be a fuel pressure or delivery problem.

Now for some possible solutions:

* Inspect all vacuum and PCV hoses, replace if necessary.

* Clean the MAF sensor. Consult your service manual for it's location if you need help, and use MAF Cleaner available at your auto parts store. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling it.

* Inspect fuel lines for cracks, leaks, or pinches.

* Have the fuel pressure at the fuel rail checked by a professional technician, the fuel line pressures found on the Direct Injected LNF engines are dangerous if you aren't 100% certain of your mechanical proficiency.

* Use fuel injector cleaner or get them professionally cleaned/replaced.

* Check for an exhaust leak before the first oxygen sensor, and correct if necessary.

That last item "Check for an exhaust leak before the first oxygen sensor" means flex pipe or sometimes gasket.

I have a 2008 2.2 5sp. Could have been wildly different if we were trying to diagnose that problem on a Non-Turbo HHR, than for one. SS present a different system with different routing for certain things.

Really is helpful to have Year, Model, Motor Size(Non-SS) and Mileage! Helps determine possible other causes due to age, or potential underlying problems that certain years may have experienced compared to others!

Ah yes. 2.2 is correct. And mileage is 68911

Did this start up right after a air filter change?
MAF connector

Does the car make a louder than normal noise under the hood?
Flex pipe