I have a 2008 HHR LS with 130k. For about the last 40k or so, I consistently notice a bit of rough idle at times (maybe 200rpm or so dips), and when really stepping on the pedal up a long hill or such, the car hesitates a bit intermittently. I replaced the plugs at 95k, I replaced the coil packs about 30k ago due to the car losing power and literally jerking going up long hills (no cel- it fixed the problem though), and I replaced the upstream O2 sensor about 15k ago (bank 1 lean cel). I recently ran two tanks of Red line fuel cleaner and several tanks of Lucas through it. I never get a cel. I clean the air filter (k&n), intake, and maf sensor regularly. I can't figure out what else to check.

I'm thinking of replacing the injectors with the thought that one of them isn't spraying quite right. Any other ideas?

 

Fuel supply, throttle body dirty.

By bank 1 lean, do you mean "stuck lean", if so then #2 O2 sensor is suspect.

 

I forget the exact code, but it was for the upstream O2 sensor, and replacing it fixed the cel. I do need a better understanding of how to read fuel trims though and really understand what they mean. As for the throttle body, I spray it out with TB cleaner regularly.

 

Check the fuel pressure. May even relate to that O2 code. I am thinking fuel pump, filter is integral.

 

X2 what Don said!

 

I'll pick up a gauge tomorrow and see if I can dig up what the correct readings should be in the manual. I don't know what u mean by the "filter is integral" because as u know there is no fuel filter

 

There is a filter in the fuel pump.

 

That's the nice way of saying, clogged filter = fuel pump replacement.

Why GM decided to do away with serviceable fuel filters is a bit of a mystery, but most likely related to unit cost vs. failure rates in the field.

 

I didn't realize that there is a filter in with the fuel pump. Real nice GM.

I looked for a while through the service manual (electronic copy), and don't see where it says the fuel pressure should be 50-60psi like I am reading is supposed to be correct.

In reading the procedure, it says to have the engine off, ignition on, and use a scan tool to turn the pump on. I'm in the dark here. The things I read on the web in general say to check the pressure with the engine running. I have no idea what the service manual means when it says to use a scan tool to turn the pump on. Shouldn't there be a relay that you can manually jump to make the pump come on?

 

The service manual is referring to a Tech II scanner. I have read that same info in the service manual.
The Tech II is a service controller unit(for lack of a better term). It is not just a code scanner.