Engine Runs Rough
If you find any of these trouble codes P0300, P0301, P0302, P0303, P0304, P0305, P0306, read this. Here’s how to diagnose engine runs rough after going through a puddle on any of these vehicles: 2008-2009 Chevrolet Colorado, TrailBlazer, 2008-2009 GMC Canyon, Envoy, 2008-2009 HUMMER H3, H3T, 2008-2009 Saab 9-7X, All Equipped With Engine RPOs LLR, LLV, LL8, here’s what to check out.
The ignition coil bolts on these vehicles is vented. If you drive through puddles and water splashes onto the bolt vent holes, the water will seep down into the spark plug well and cause misfires. Remove the coils and check for water in the spark plug well. If you find water, suck it out with a vacuum or blow it out with compressed air. Then replace the spark plug. Next, buy a tube of Loctite® 565 PST Thread Sealant and fill the bottom of the ignition coil bolt hole vent. Apply it to the bolt threads as well. Then clear the trouble codes and check for misfires again. If you still have misfires, replace the affecting ignition coils. The sealant will prevent water from seeping into the spark plug wells in the future.
© 2012 Rick Muscoplat
Posted on by Rick Muscoplat