tribal_sun

2005 Cobalt 2.2 113,000 miles
-K&N Typhoon Ram Air, 2 years old
-Bosch Platinum +4 spark plugs, 10,000 miles old
-Ignition control module is 4 years old.
-Battery is 6 years old, but tested out well.
-Ignition Coil is original.
-Ignition Coil wires are 4 years old.

The engine turns over but doesn't fire, the RPM rises to 500 so I assume the crank sensor and timing belt are working. I pulled one of the plugs and it was wet fouled and black so I think the injectors are working. The fuel pump hums when I turn the key and I smell gas after trying to start it. I took off the ignition coil and put new spark plugs on the ends of the wires. The outside plugs spark but the two inside plugs do nothing. I'm stuck and more than open to help or suggestions.

Thanks guys.

Sl0wbaltSS

timing chain? Does it sound like it's firing at all? Plugs should be like a brown. These engines run hella lean. 6 year old battery too, replace it. See if you're getting spark, take out a spark plug, attach it to the coil and turn over the engine and have a second guy look at it if it's sparking.

T-fog

I would start by swap coils around to see if they are your issue, They are pretty common.

Hope this helps, Keep us posted.

tribal_sun

I had an auto parts store re-charge and test the battery, everything came back good. I took out the ICM/Coil/Coilpacks and attached new plugs to see if there was at least a spark. 1 and 4 sparked fine, but 2 and 3 didn't do a thing. I replaced the coilpacks on 2 and 3 and still nothing. I'm leaning towards the ignition coil being bad. I have a new ICM, Coil, Coilpacks, and plugs so tomorrow morning I will switch in and out with new parts to see what's working and what's not. I will update tomorrow with anything more i find. Thanks for the correspondence!

09CobaltSS1

These (your engine specifically not ALL ecotecs) are a waste spark style type of ignition. The way the circuits are set up to fire are basically 1&4 and 2&3. These are actually relatively basic ignition systems, so, if you have already replaced the coil packs and primary coil that leaves a few basic areas left. Module voltage feed, 1&4 coil pulse voltage feed, 2&3 coil pulse voltage feed and grounds.

Just going on a hunch on how these types of systems fail, they generally fail in 2 ways with this same condition you're experiencing. Either a bad coil or a bad transistor circuit in the ignition module. Without any real testing and troubleshooting being done it's pretty tough to nail down one or the other, but my guess is you most likely have a bad transistor circuit in the ignition module for the 2&3 coil circuits.

tribal_sun

So I switched out the battery and put the old ICM, Coilpacks, and Coil back on, and it started. I re-thought the battery and jumped to see if it would start and it did, leading me to think the battery needed replacement.

Bad news is it idles really rough, there's a strange vibration and the engine light is starting to flash. Now I'm really stumped and open to any ideas. I will replace the ICM, Coilpacks, and Coil tomorrow morning with new so it's all new and see if I still get the vibration and flashing engine light. What is the vibration and rough idle? Maybe it's the 2 and 3 plugs not getting spark from the old ICM and Coil?

09CobaltSS1

I'm sort of flying blind without ever touching the car, but that would be my guess at this point.

A flashing cel is likely due to misfire. It would be a pretty safe bet to assume that if you hooked up a scan tool you'd find a pending P0300, P0302, P0303 or some combination of the 3.

tribal_sun

Changed out the old ICM with a new one this morning, started up fine but RPMs were a little high (1.5 instead of around 1). Shut it off and started it a couple times and didn't notice the rough idle or vibrations or engine light flashing. Drive it around the block to test and didn't feel/hear/smell anything suspect. Parked and shut it off. Turned it on and the idle came back to normal and no issues so far.

Looks like it was a bad ICM as was suggested(and the older battery wasn't helping either I suspect), thank you guys for all the help and I'll post an update in a week or two to report any differences if any.

09CobaltSS1

Good to hear man. With a waste spark system like that, 8/10 it's usually the module when it fails the way yours did. 2 plugs on the same pulse circuit is a pretty dead giveaway.

tribal_sun

Back at it again, here's a recap of the specs:

2005 Cobalt 2.2 116,000 miles
-K&N Typhoon Ram Air, 2 years old
-Bosch Platinum +4 spark plugs, 3,000 miles old
-Ignition control module is new (1/2015).
-Battery is new (1/2015).
-Ignition Coil is new (1/2015).
-Ignition Coil wires are new (1/2015).

Engine light would come on with the same code P0300, cylinder misfire. After a day it would correct itself and turn off. This cycle happened about every 4 days. Now the engine light is consistently on, and flashes when the car exceeds 20mph.

Diagnostics so far:

-Fuel injectors are clicking away as usual (Auto stethoscope confirms this)
-Air Filter has some fuzz and dirt (I really don't think this is the problem as the MAF would've piped up too, but cleaning the filter anyway) Here's the filter before cleaning:

-Swapped out the Bosch spark plugs for OEM AcDelco plugs, gapped at .040. Here's the Bosch plugs after 3000 miles:


The code reader I have (Innova 3140B) did show a Fuel Sys1 OL-Fault code, but not sure if because engine was cold when started and tested or if indeed have a bad O2 sensor. Will test when air filter is re-oiled and installed.

Any and all help is greatly appreciated.

tribal_sun

Did some troubleshooting this evening.

Didn't realize the coil boots (black rubber boot with spring inside) were original (I never replaced them), so I installed new ones. That cleared the CEL code PM0300, and it idled a little better. I wondered if there was some residue to burn out of the cylinders and it would correct itself.

I drove it around the block and the CEL threw another code: PM0304, Cylinder misfire in #4. I pulled the plug and it was gapped a little wide at .045 so I changed it to between .038 and .040. Started it up and cleared the code. Idle ran well and consistent, drove it around the block again and now it's throwing a PM0301 #1 Cylinder misfire. Before I double-check the gap, am I heading towards a particular path that any of you might be familiar with?

-I've read about the wiring harness to the ICM being faulty but all wires are tight and sheathing isn't brittle.
-Could be a lemon IC or ICM, but I don't think that's the case.
-Any other ideas?

tribal_sun

Ended up taking it to the shop. Learned some interesting points:

The culprit was the ICM AND Ignition coil. Parts were under a year old so I didn't think to test them, moral of this story is don't assume anything. Luckily I was able to return the old parts under warranty so the shop bill wasn't too bad. I appreciate experienced eyes tracing the wires and grounds to make sure everything is tight and connected. Another strange bit the mechanic told me is that the coolant has a slight negative charge.

Hope this helps the next cobalt owner with a similar problem!