05 sunfire ecotec no start

OK, this is gonna be a long one:

2005 Sunfire w. a manual transmission…came in missing BAD on #2 and 3, P0300 but live data showed it was only 2 and 3. It stank of fuel and was glowing red hot at the rear of the converter – pulled the converter and put in a straight pipe so I didn’t damage the converter during testing – Tried a brand new coil pack (same control module and plugs, the plugs looked good.) and it ran much the same.

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Subject: SES Light and Severe Engine Misfire on Cylinder 1 and 4 or Cylinders 2 and 3 Due to a Repeat Ignition Module Concern – keywords ICM miss no P0300 P0301 P0302 P0303 P0304 plug spark #PIP3433B – (10/20/2005)

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The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
Some customers may comment on a severe engine misfire and a SES Light. Upon inspection, DTCs P0300 – P0304 may be found due to misfires on cylinders 1 and 4 or cylinders 2 and 3.

Recommendation/Instructions:
If ICM (ignition control module) replacement temporarily corrected the above issue only to have the same concern return again, perform the SI diagnostics. If the SI diagnostics lead to ICM replacement again, something may have damaged the ICM causing the vehicle to return with the same concern again. If it appears that something has damaged the ICM, replace the ICM as directed by SI, ensure that the ICM ground is clean and tight, and replace all of the spark plugs to possibly prevent ICM damage again.

If the SI diagnostics do not isolate a cause for the above concern due to the intermittent nature, inspect circuits 406 (IC Control for 2/3 Coil) and 423 (IC Control for 1/4 Coil) for an intermittent short to ground. Depending on the model, this may occur on the AC lines near the AC compressor, on the transmission mount, or on the transmission lines where they enter the transmission. If no shorts are found, inspect the ignition control module ground to ensure that it is clean and tight.

Today, per the TSB, I checked for a ground on the control wire for the 2/3 coil, T pin in the connector at the coil and a test light, hooked the clip end of the light to battery positive. It didn’t light as brightly as when I checked my test light prior to that, it’s not a full 12v. When the test light made contact with the T pin, you could hear the fuel pump relay clicking rapidly. The light would still illuminate with no relay present.

Could not find a short in the entire length of the wire, despite the weak ground being present at all times (key off)…I am confused by that one. It’s entirely possible that I am missing something here, but there are no splices or connectors besides a main bulkhead connector that it runs through before it gets to the computer and no issues there.

Now the damn thing won’t even start – Cranks but doesn’t run. It starts and dies with starter fluid, so I know I at least have enough spark to run. Came to find the fuel pump isn’t priming, but runs when you give it 12v. Relay still closes, fuse is good. No power to the pump.

Getting a pile of communication errors now as well. Had a BCM communication error yesterday (when it still ran) but getting that AND a PCM comm. error now, and when it tries to run tests the dash lights go bonkers and the digital odometer actually displays “Error”…it’s acting like a security system is keeping the engine from starting but the light isn’t blinking when you crank it and there’s no chip in the key. Like I said, it started and ran like shit yesterday before I began looking for a short in that wire harness and found none, despite the test light lighting.

Have access to a junkyard and can test parts before paying to see if it’s actually my problem. Based on all of the communication errors I am thinking a computer problem and may try a known good ECU and see what happens. Just a thought.

Any thoughts you might have would be appreciated.