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Owned this car for two years with no issues. About 18500 original miles. A couple of days ago engine started to misfire under load and at idle after warm-up. No codes or messages on the DIC. I'm suspecting plugs, plug wires or coil packs. Plugs are Part number 12571164 AC Delco and may be original to the car. They look like they could use a clean-up but otherwise look ok. No cracks I can detect in the porcelain. Plug wires look good.
Owner's Manual says to replace at 100K miles and I'm way under that. Should I go ahead and replace plugs anyway or is there something else to check first?
R & R the plugs and wires. Even with only 18,500 miles, it's the 19 years in service thing you've got. Besides, if you still have the mis-fire, you can keep searching as the plugs/wires should be ruled out.
Here's what plugs (OEM) look like after 94,XXX miles (and 20 years.) And I had no mis-fire, and it passed smog!
Doubtful it's a coil pack so anything beyond you changing plugs and wires to diagnose your misfire will require advanced diagnostic equipment...a P0300 is a "2 trip" DTC so it may need to happen again to throw a DTC and illuminate the MIL.
I agree. Time to retire these old plugs and hopefully fix the problem.
Local Chevy dealer shows AC Delco PN 19417055, 41-162 as the current OEM replacement for $17.60 plus tax. Best deal is AutoZone. $93 total, two-day delivery to home. GM Parts Direct slightly more expensive than AutoZone, longer delivery time. Same price as dealer quoted but discounted on Parts Direct plus shipping and handling.
I'll be interested to see where they're made now. My originals are stamped "Assembled in USA with Japanese and USA parts.
R & R the plugs and wires. Even with only 18,500 miles, it's the 19 years in service thing you've got. Besides, if you still have the mis-fire, you can keep searching as the plugs/wires should be ruled out.
Here's what plugs (OEM) look like after 94,XXX miles (and 20 years.) And I had no mis-fire, and it passed smog!
Got the new 41-162 plugs today. Here’s a side by side pic of them with the original 41-985 plugs. No country of origin or assembly stamped on the new plug.The differences between the two are obvious.
2008 Base Model Engine Mis-Fire
