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04 Dodge Van 3.3 liter,code PO 303 # 3 cyl misfire

Code PO 303 # 3 cyl misfire . Car has medium studder, comes and goes, runs better when warm,
does not kill at stops. Changed plugs, wires, vac hoses, fuel inj., plenum seals, compression 170#, checked inj. wiring on short harness, repaired vac hose on big box under dr. seat. Checked intake leaks.Still has # 3 mis fire off and on. HELP or Salvage yard and sale on new used parts.

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  • Dodge Master
  • 14,594 Answers

Hook up a vacuum gauge .
Vacuum test 01

Posted on Aug 08, 2017


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SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

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Posted on Jan 02, 2017

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SOURCE: 95 GMC Jimmy 4.3l W vin rough idle

My problem was solved when I repaired my 4 wd activation dash switch. The switch was contacting on 2WD & 4HI at the same time. The front differential activation is vacuum activated possibly creating a tug of war that didn't actually engage it but drained off vacuum from the engine? A theory at best but stumbbled across it because I knew the switch wasn't working properly I repaired it and low and behold rough idle disappeared and all is good for 3 weeks running.

Posted on Dec 10, 2008

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SOURCE: car wont start

spray starting fluid in the air intake , if it fires you have a fuel problem , if it dont you have ign. trouble

Posted on Nov 10, 2009

SOURCE: 04' Ram 1500, bad mis-fire. cust repl s/plugs. no

You still have random misfires (PO300)
You most likely replaced those coils that set a code, and those were not the one bad offender,spiking the computer module.
Take a new coil and put in a cylinder,no change, replace old coil and move new one to next cylinder. You can do that once or twice a day, if you have nothing else to do. You need a 90 degree day, to really get that solved,unless you have an ignition oscilloscope.
Never had a bad spark plug in 45 years.

Posted on Sep 18, 2010

  • 11 Answers

SOURCE: 96 dodge intrepid cyl 6

I would check the sensor. If everything is working properly (as you have described), I would guess the sensor or computer module.

Posted on Jan 07, 2011

  • 1871 Answers

SOURCE: Truck has been sitting for almost a month in

Hello! Sounds as if you were successful..However, this is being listed as a trouble report...Is the F 150 running OK; Or does it still have a problem?....Guru...Saailer

Posted on Jan 15, 2011

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1 Answer

02 Toyota Tacoma when engine warms up cylinder 3 has a misfire po303

check spark plug of the cyl. switch plug with another cyl, run engine until warm to see if misfire still comes on. if it stays on the same cyl. fault could be high tension wire or coil or worse leaky valve or rings. if misfire switched to the other cyl just change plug or better replace all plugs

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Is the van running rough at idle? Does it seems to have a slight miss as you accel? What kind of mileage do you have. Ford 4.2L with high mileage could have EGR ports that are clogged in the lower intake. Unplug the EGR vacuum line and see if the misfire goes away ( 303 is a cylinder #3 misfire code )

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The code means that cylinder had no power at some point in time.
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Most likely ,even though you have a 303 code, that
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Need to put the old coil back & walk new one to different
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Engine idles roughly- seems to be missing OBD2 code reads PO 303 and check engine light flashes this on a 2003 Dodge Caravan 4 cyl engine

check spark plug and ignition wire on #3 cylinder (count from front of engine. If plug and wire good, do compression test.

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Code Po171, P0174 P0403 . Upon acceleration....truck is jumping. One code metioned Cyl 3 misfire

PO 171 & 174-are O2 Sensors Codes,forget them,just be sure their screwed in tight. Yes ,they will come loose.
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PO-403 -is EGR related.-That probably is shot, also.

Had all thoses and more, on my Lincoln Ls

A misfire will set many codes,that while not unrelated,are not your issuse. You need to understand the symptom,is not always what caused the codes,or not the cause of the problem.

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2001 Pontiac Montana - what is a misfire #5?

Without your actual trouble code, I am assuming that you are have a misfire on cylinder # 5. The computer cannot really tell what is causing the misfire only that cyl 5 is not putting out full power. If it misfires when cold then smooths out as it warms up, I would say it is probably an injector that is sticky, as it warms up it starts working properly.

Apr 29, 2010 | 2001 Pontiac Montana

1 Answer

1999 safari van 4.3 6 cyl. has a service code PO

P0301 is a DTC code that indicates a misfire to cylinder one. It could be a bad spark plug, spark plug wire, rotor and cap, a dirty fuel injector, or the worst a bad head gasket. Cylinder 1 is the first cylinder on the drivers side, towards the front. Start with the simple and check the spark plug wire and add fuel injector cleaner to the gas tank. Good luck and hope this helps you get you van running 100% soon. If that did not help, then your going to have to do a tune up by replacing the spark plugs, wires and rotor and cap. You can get all the parts you need at Auto Zone and they can give you the step by step to get the job done with common tools in under 2 hours of your time. Keep me posted, be glad to know you got your van running 100% again soon.

Oct 27, 2009 | 1999 GMC Safari

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