Hi all, I've been lurking for a while, but finally had a problem I couldn't find an answer for. There are so many knowledgeable people here, I thought this is the best place to get advice. Here's a short rundown on my vehicle:

09 hhr 2.2l, auto, bought at 75k, now at 125k. I'm a courier, I drive about 10k a month in this car. Mostly highway miles, in the hills of middle tennessee.

About a month ago, while the car was idling for about five minutes following a 150 mile drive, the SERVICE ESC/TSC lights came on. I drove a mile to a gas station, filled up, and started the 100 mile drive home. When I turned the car back on, the check engine light was on too. Took it Oreilleys to scan the engine. Had three codes, two of which were misfire codes p0300, p0304, c0561.

P0300 Engine Misfire Detected
P0304 Cylinder 4 Misfire Detected
C0561 System Disabled Information Stored


On the way home, the service esc/tsc lights went off.

Car runs fine, although the idle may be slightly rougher than when I bought it. I had replaced the spark plugs about 5k before the problem started. I replaced the #4 coil in an attempt to fix the misfire code. That seemed to fix the problem for a few thousand miles. Then the CEL light started coming back on. A few mintues at a time, more frequently over time. Now it is nearly always on, and the service esc/tsc light is also back.

Scanned engine again this morning. Came back with P0304, C0700, and C0A00. A google search indicates the C0700 is related to the tcm. I can't find anything on the C0A00. I should add that this scan was done with an OBD2 scanner bought off amazon and hooked up to my laptop.

The car drives fine. MPG is unchanged since I bought it. Always around 29mpg. I'm hoping fixing the misfire code clears the others.

Any ideas/suggestions/criticism would be greatly appreciated. My searches lead me to a fuel injector problem or burnt valve if the plug/coil isn't the problem. Before I start throwing more parts at it I'm hoping to get some knowledgeable advice.

Thanks for any help!

 

Welcome to the site.

1st a question. Did you replace the plugs with original type AC iridium ones ? Reason for asking is,other folks on this site have had "issues" when changing to another brand/type of plug.
These little Ecotec engines can be finicky as far as using the original type plugs.

 

I was getting an intermittent P304 code as well starting about a year ago. I ran a few tanks of premium and that seemed to help - but it came back. I tried a couple different fuel additives that professed to clean out carbon in the cylinders, valves etc. - and that seemed to help for a while. But it came back infrequently. The last thing done was I added a full can of Seafoam gas additive to a partial tank and ran it quite low before filling up again. It's been well over a month now, and it hasn't come back.

The other codes maybe related to the hubs starting to go which can affect the traction control. That's similar to our HHR as well - I should get looking for new hubs (easy job to replace and well documented here in the How-To section).

thanks for the reminder about the plugs FMG - mine are definitely due for replacement.

 

X2 whopper been a year for me !!! Make sure you have the stock plugs installed per gap from the factory

 

Yes, I used the acdelco iridium plugs specified in the owners manual.


I use 89 octane shell or bp gas 95% of the time, and a PEA based fuel injector cleaner about once a month. I have seen a couple people mention seafoam while searching other threads. I'll give that a try as I've never used it on this vehicle.

Thanks for all the advice so far.

 

Yeah Seafoam - a lot of people praise it like is an elixir from the Gods. That was the first time I tried it - I'm almost a fan now.

 

Update:

I've run a can of seafoam through the gas tank, and nothing but shell premium for about 1500 miles. I also replaced fuel injector #4. I also pulled the #4 sparkplug to see what it looked like.

The problem has only gotten worse, with the service ESC light on 90% of the time, and the check engine light on continuously now. The only thing that made the light go off was when I removed the old plug to inspect it. When I put it back together, all of the warning lights went off for about 250 miles. But they came back on about 1k ago, worse than before.

One other thing I have noticed is that although the check engine light stays on continuously, the service traction control light usually only comes on when I am stopped and idling.

I also noticed a little bit of oily crud above a sensor at the front center of the vehicle. The sensor is in the general vicinity of the hood latch. I am not sure which sensor it is, or the source of the oil. It wasn't much but it hasn't been there in the past.

At this point the only other thing I can think to do is test compression. Any other input at all would be greatly appreciated. Thank you for reading this.

 

I maybe way off-base, but that plug looks like it is running a bit lean - OLDLUE, what's your take on it?

Have you checked to see what CEL codes are there currently?

Maybe the ESC - T/C errors are a hub problem, and you have been looking at two different issues?

 

P304 c0700 are the codes. The two lights came on within an hour of each other which is what makes me think they are related. My Research has also suggested that a misfire condition can trigger a traction control shut down.

If it is running lean, what are some things I should look at? Thank you for your help

 

I concur, that looks lean
That oil thingy is your throttle body, be careful and clean it with TB cleaner
At the electrical harness check those wires for a loose connection clean that connection
Slather some dielectric grease on it.
Check and clean your MAF sensor with the correct cleaner and check those pins