Another Misfire issue

[wehan]

2007 Chevy Cobalt coupe ls 2.2l 160k miles.

Getting a bad misfire while driving and at idle, under hard acceleration it seems to go away. Codes p0301 and p0351. I swapped the coils around and it still gives the same codes. going to hardware store for new plugs and a couple bottles of lucas injector cleaner soon.

Any ideas?

 

[YelloEye]

Don't use Lukas, get Chevron Concentrated Fuel System Cleaner. It's the stuff GM uses, rebranded.

The P0301 is likely caused by the P0351, so ignore that until the P0351 is gone.

I'll have to check my service books later to see what the diag is for that code.

 

[wehan]

OK will do. Won't get to it until this weekend but I'll check compression while I have the plugs out.

oh and the generic for those codes is:

P0351: Ignition Coil A Primary/Secondary Circuit Malfunction

P0301: Cylinder #1 Misfire

 

[YelloEye]

The ECM is really good about telling you when electrical bits are broken. (Your thread on great lakes 4x4 mentioned it was fine 9/10 times)

Check your coil wires for chafing.

 

[wehan]

I didn't see anything when I swapped coils around but I will double check. You a member on gl4x4 YelloEye??

 

[YelloEye]

No, a Google search for cobalt and P0351 pulled it up on the first page.

 

[YelloEye]

So the P0351 is High Resistance or an Open on the Control Circuit. That's the PU (I assume purple) wire on that connector.

Ground is Black
Brown is Low Reference
Purple is Control
Pink/Black is Ignition Voltage

Diagnostics
1. Ignition OFF, disconnect the harness connector at the affected ignition coil/module.
2. Ignition OFF for 90 seconds, disconnect the X1 harness connector at the ECM.
3. Test for less than 5.0 ohms between the ignition coil/module IC circuit terminal 3:
• IC 1 circuit: terminal 55 X1

• IC 2 circuit: terminal 80 X1

• IC 3 circuit: terminal 79 X1

• IC 4 circuit: terminal 56 X1

⇒ If greater than the specified range, test the IC circuit for an open/high resistance.

4. Connect the ECM.
5. Exchange the affected ignition coil/module with the ignition/coil module of a good cylinder.
6. Start the engine and observe the scan tool.
⇒ If the DTC or the misfire transfers with the suspect ignition/coil module, replace as needed.

⇒ If the DTC or the misfire does not transfer with the suspect ignition/coil module, replace the ECM.

 

[wehan]

Awesome, thanks. Now to decipher that and apply it to my problem.

 

[wehan]

Ok, so I checked between pin 3 on the coil plug on cylinder 1 and pin 55 on the x1 plug. Came up .5ohm. Also checked on cylinder 4 and got .7ohm. I am however not able to locate terminal 80 x1 or 79 x1. Where are these pins at? As far as I can tell the x1 up only has 72 pins.

 

[YelloEye]

I'll have to check the books again when I get home. Could it be that it's continued on the other connector?

Also, how's the connector look? It might be an intermittent signal issue, broken wire would do it, check right up next to the plug. If you can try having your meter hooked up while bending the wires a little to see if it shows open.