05 Chevrolet cobalt puttering, cuts off. code: P0300

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cobalt1217
Posts: 1
Joined: Tue Aug 06, 2013 6:50 pm

05 Chevrolet cobalt puttering, cuts off. code: P0300

Unread post by cobalt1217 » Tue Aug 06, 2013 7:08 pm

My '05 Chevrolet cobalt 4 cylnd. Has been puttering badly, acts like it wants to cut off, sometimes it does at a stop. Had engine replaced with '06 engine roundabout a year or so ago. thought maybe bad gas. Put sea foam in it same results. Had test done read code: P0300..misfiring. replaced knock sensor and spark plugs. Same results. Any ideas?

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carriedi
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Joined: Wed Apr 10, 2013 12:42 pm

Re: 05 Chevrolet cobalt puttering, cuts off. code: P0300

Unread post by carriedi » Wed Aug 07, 2013 7:30 pm

P0300 is not enough information to make a diagnosis. It just tells you what you already know. Your engine is misfiring. You will need to hook up a scanner and look at what the engine is doing. Misfire counter will give you a clue if one cylinder is acting up more than others. Fuel trim will help you see if you're running a lean condition. Exhaust gasses will let you know if you have an injector not letting enough fuel or a coil not firing. (o2 and HC's) Fuel pressure and volume could cause a problem but not usually a missing condition but a good check just in case.

do you have the 2.0L or the 2.2L engine? 2.2 engines can have a problem with coil, just like the quad4's did, where it will short out a couple cylinders. (2.0 will have COP so not so much) You would be able to see the effect with the misfire counter on the scanner. Two cylinders will misfire more that the others.

has the engine been running fine since you installed the 06 motor and just recently started to run badly or have you had a slight problem that has gotten worse? How many miles is on the replacement motor? there are issues with timing chains on some 2.2L. you may want to verify your timing all matches up.
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TerryAuto
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Joined: Fri Dec 11, 2009 8:48 pm

Re: 05 Chevrolet cobalt puttering, cuts off. code: P0300

Unread post by TerryAuto » Wed Aug 07, 2013 10:57 pm

cobalt1217 wrote:My '05 Chevrolet cobalt 4 cylnd. Has been puttering badly, acts like it wants to cut off, sometimes it does at a stop. Had engine replaced with '06 engine roundabout a year or so ago. thought maybe bad gas. Put sea foam in it same results. Had test done read code: P0300..misfiring. replaced knock sensor and spark plugs. Same results. Any ideas?
You may also have a problem with the cylinder head and valves. See this link for information on
Chevy Cobalt P0300 at Idle

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