I don't know how best to describe this but a few weeks ago my 2010 hhr developed an issue when you start it. It fires right up every time but I would say its a harder start then normal, feels like it shakes the engine a little more. Then after it fires it seems to slowly come up to idle rpm. Almost like it is missing as it idles up. I'd say its a rough idle for a little bit. After that it's fine. The check engine light hasn't came on either.

I thought it might just have been the gas at first but I've ran a couple tanks through it since then and some fuel injector cleaner. Also changed the spark plugs just to rule that out. Pulled the MAF sensor out and looked at it and it was as clean looking as brand new. Car just rolled over 60,000 miles and I am religious about maintenance. Any ideas about what I should look into?

 

Your first step would be to have the codes pulled, even if you have no check engine light on as I suspect, it will store codes. Most if not all auto parts stores will do for free, then provide you with a print out.

My first thought is that your throttle body may need cleaned, but it could also be a failing fuel pressure regulator or fuel pump causing a starvation issue.

If you can get your codes pulled up and then post them here, it'll help in providing some more definate areas to look at.

 

Auto zone pulled the codes for me. Had two stored codes both p0171 lean fuel reading on bank 1. The guy told me the most likely reasons were MAF sensor, oxygen sensor, fuel pressure regulator or fuel pump. I don't think it's the pump since it is only on start up and runs fine after 30 seconds or so. But I've been wrong before. :)

 

Check your PM for a link to the test procedure for P0171. Let me know when and if you DL the file. If it does not work, I can send it in another way.

 

I got the file. Thanks.

 

There is a whole lot more in the Mitchell OnDemand. Basically sounds like a vacuum leak hiding somewhere.