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Dodge Repair/'04 GrandCaravan SE 3.3: Code P0300

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QUESTION: Please Help...its my handicap van,cold starts it misfires,when warms up,it runs smooth,besides burning gas like crazy..Already,plugs,wires,coil,injector,fuel pump,crank sensor and inspected fuel injector wire harness..now,im broke and don't know what else to trouble shoot.thanks

ANSWER: Hi Tony,
Take advantage of the on-board self-diagnostic capability by using the ignition switch: "on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then watch the odometer window to see the mileage replaced by a 4-digit number(s) preceded by a P. Let me know what you find and we'll go from there.
If you already know that cylinder #1 is misfiring then we'll focus on that cylinder only.
One thing to check would be the egr valve which is located on the corner of the engine near the oil filler cap. It has a pipe that runs to it from the nearby exhaust manifold. It has a round top and between that and the valve body you will see a flange which conceals the valve stem. That stem has a slot around its circumference which you can insert the tip of a screwdriver into and then move the stem up and down to check that it moves freely, against internal spring action that closes the valve. If the valve is gummed up it can stick ajar and that can cause a misfire. So spray some WD-40 on the valve stem where it enter the body of the valve and then exercise the stem back and forth to free up the action.
Roland

---------- FOLLOW-UP ----------

QUESTION: Ok,sorry..cleaned egr and throttle body..not 100% about the lil valve moving,but will check..i have access to a code reader,not a snap on,but a code reader..lol..if i earase code,i can drive about 100 miles before it comes back on...thanks for the fast reply..

ANSWER: Was the code '0301'? Do check the action of the valve.

---------- FOLLOW-UP ----------

QUESTION: its a p0300.no smoking at all.that was bought to my att.thinking bout trying marvel mystry oil in fuel and oil..or ecm,what do u think?

Answer
Hi Tony,
The 0300 is a multiple cylinder misfire, not a "cylinder 1 misfire". So for the record I will change that in the question name.
You also said that it runs OK after warming up. I would suggest that you check the resistance of the coolant temp sensor when cold, then keep measuring in steps as the engine warms up. That might be causing the poor firing if the mixture was wrong at start up. Let me know what you find with that. And do check the egr valve stem for its "action". You have otherwise looked into the usual areas for that code.
Roland  

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Roland Finston

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Get a Free Fast answer to your repair question about a Chrysler/Dodge/Plymouth car, minivan, SUV, or truck. Problems with electronically controlled engines and transmissions as well as body wiring problems are my specialty. This free troubleshoot advice forum helps you diagnose faults, minimize repair costs or do-it-yourself.

I answer questions seven days a week and respond to you in about 30 minutes. "Maxed Out" means I am answering another question or asleep overnight so try again later.

I have do-it-yourself experience (50+ years) and a library of 100 1982-2012 Chrysler factory shop manuals and 20 multi-manual Chrysler Corp. CD's.

I was voted "Top expert" from 2010-2015 here at AllExperts, and have answered 20,000+ questions.

Experience

Five decades as a 'do-it-yourselfer' on domestic and imported cars

Organizations
Yahoo Autos Group called The Chrysler Lebaron Club (co-moderator)

Education/Credentials
Degrees in Physics/bruised knuckles.

Awards and Honors
"Top expert" of 2010, 2011, 2012, 2013, 2014, and 2015 here at Allexperts. Quickest "average response time" at Allexperts (currently no. 1).

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