Misfire

2003 CHEVROLET S-10
112,200 MILES • 2.2L • 4 CYL • 2WD • MANUAL
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JOHN BLACKETT
  • MEMBER
  • 1 POST
One or two starts a week in morning when cold, engine stumbles and misfires gets down to about 500 rpm, normal idle is around 900, but does not stall. Does this until warmed up. no misfire codes and otherwise runs normal. New plugs and wires, new coil packs installed and injectors have been cleaned.
Dec 18, 2017 at 9:22 PM
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HARRY P
  • AUTOMOTIVE REPAIR CONTRIBUTOR
  • 2,292 POSTS
Hmm, it is always fun chasing an intermittent problem. At that mileage, I would probably start with changing the fuel filter. They usually need changing somewhere around 100,000 miles. I would also get some mass air flow sensor cleaner ($3.00 to $4.00 at Autozone) and clean the MAF sensor.

How a MAF sensor works: https://www.2carpros.com/articles/how-a-mass-air-flow-sensor-works-maf

How to clean a MAF sensor: https://www.2carpros.com/articles/mass-air-flow-service

Also, look for vacuum leaks and signs of any leaks on the air intake box/duct. Check this guide out: https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Also, I do not think the PCV would be causing this, but if it has not been changed in a while then it would not be a bad idea to do that as well.

I know it sounds like a good amount of guesswork, but sometimes it really should not take too long to go through all of that. Please try these and let us know what you find. We will go from there if needed.
Dec 19, 2017 at 4:36 AM
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