Ok nope it's back to surging already. I'm taking it right now to get the codes and I'll report back with the codes
Codes p0603,p0118,p0315,p0480,p0604,p062f

 

When did you replace the ECM and why?

The wiring from your cooling fan relay to the ECM is compromised.
The wiring from the coolant temp sensor to the ECM is compromised.

 

I have not replaced the ecm on it.
Right after I git codes read it really started running like ****. Had no power and wouldn't hardly go down road. Barely made it home. Making a sputtering noise.
Ohand they have the cooling fan wired direct and on a toggle switch cause I guess it wasn't working wired correctly.

 

You only get the P0315 if you install a new ECM without learning the crankshaft.
This is the only time I have ever said "it must be the computer".
Shoot who ever decided a toggle switch was smarter than a computer.

 

The ecm hasn't been replaced is what they say. And I know a toggle switch for your fan but I tried to hook it back up right and it would not come on. I have the new ecm on the way so hopefully that will fix it.

 

It will still have to be programmed to your VIN.
Plus the crankshaft sensor.

Don correct me if I'm wrong.

 

That is correct. There used to be a couple of vendors on eBay that would program a used ECM to your VIN for about $100. You will then get the P0315 which means "crankshaft not learned". They include weird directions for resetting the security system that does not apply to HHR.

If you just switch an ECM from another HHR you won't get the P0315 because it is using the data from the donor; so it does need to be re learned for efficiency. It will run without just not optimized. There are other problems with that scenario.

 

The OP did state that the engine was replaced by the previous owner.
Don. Could that be the reason for the P0315 ?

 

P0315 means NO DATA for the crankshaft sensor variation. That comes from either a brand new ECM or one that has been erased. Oddly, there is no code for incorrect data.
Those other codes mean that the memory is screwed up in the ECM. A wild guess is that somebody let the positive battery cable touch the ECM housing, that happens frequently enough that there is a TSB about it.

 

Could the electrical connector to the sensor just be unplugged?