So went to start the HHR this morning, 2006 2.2L with about 101K. Started running real rough, drove around the block, check engine light starts flashing......

Make it up to Advance Auto, plug in scan tool, find multiple misfire code, and th P0128 code, which seems to be a stuck thermostat ???

Anyways Im going to pull the spark plugs in the morning, if I find one or more that look rough due to the misfiring, should I be looking at replacing the coil pack or the ignition control module. From what I read it seems it could be either one?

Any help would be greatly appreciated, and if Im totally on the wrong path by all means guide me in the right direction......

Thanks everyone!

 

If at least one cylinder doesn't show any misfire codes, you can swap a "bad coil" over and see if the problem follows the coil or stays with that cylinder.

At 100k you are due for plugs according the the manual, have you changed them?

Thermostat may be a separate issue, or with it running that bad you may not be getting up to temp in a proper time frame and it's not really stuck...

 

I did change the plugs a few months ago, around 85K miles......

The coil on this car is one piece, cant swap it around to see if it changes from plug to plug......I just dont want to drop 100 bucks on the new coil pack and find out its the ignition control module.......

 

Thermostat could possibly be the root of this problem, running colder it is programmed to run Richer fuel mix..

Could have led to a fouled spark plug or plugs imo....

edit: 2006 2.2L does NOT have multiple coil packs..

 

Did you go with the Delco Iridium plugs dudeasif, or did you use another brand? These engines are very picky about their plugs, if you used an off brand of plugs they might be causing the problem...it has happened before to others here.

 

Also could be fuel injectors. You can swap them around like suggested for the coils (I know you have the coil/ignition plate) if you have any good cylinders.

 

Sounds more like the 1 piece throttle body is crapping out. Gone are the days of just changing a throttle position sensor or cleaning the pintle of an air idle control motor.....

 

Wel I got new plugs, thermostat and a coil pack. Heading back to put it all in. I'll report back later if it fixes the problem or not....

Oh I got the Delco Iridium plugs this time...

 

Still no good, changed everything but the thermostat.....
Still missing real bad.....

I just can't see the thermostat making the car miss???

 

Still at square one, new plugs, new boots, new coil, new thermostat.....

STILL MISFIRES

What about the Ignition Control Module that sits on top of the coil pack? I mean I hate to keep throwing money into the car, Im already at 200 bucks......Ignition Control Module is another 80.....

UUGHHHH

Any more advice would be GREATLY appreciated