Question about 1996 Ford Explorer

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Check engine light on

Read code shows po306 replaced plugs and wires did compression test
all cyinders equal checked for vacum leaks replaced # six plug just t be safe

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  • David Melrose May 11, 2010

    did you reset the engine check light? Is the light still coming on?

  • Anonymous Mar 19, 2014

    The code is showing a vacum leak in air care test.



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Here are some possible causes: PO306 means cylinder #6 only.

Possible Causes check engine light on - onepx.gif Setting Conditions onepx.gif onepx.gif onepx.gif

  • Air leak in the intake manifold, or in the EGR or PCM system
  • Base engine mechanical fault that affects only one cylinder
  • Fuel delivery component fault that affects only one cylinder (i.e., a contaminated, dirty or sticking fuel injector)
  • Ignition system fault (coil or plug) that affects only one cylinder

Posted on Jan 25, 2009

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Your next step should be two things..have the injectors checked with a noid light,and have the compression checked on the #6 cyl.doing these should point you in the right direction to solve the problem

Posted on Oct 09, 2012


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code po306 refers to cylinder 6 misfire detected===causes ---engine mechanical fault--wiring--ignition/ fuel system--injector--ECT/MAF sensor--ECM

the pressure is good so rule out mechanical fault
injectors being cleaned and tested so rule out injectors
fuel pressure not tested to see if it is average or minimum
check MAF sensor for correct voltage and/ or resistance
IF the misfire moved when the plug and wires were swapped then check the wires and connections . If not then check distributor cap for crack or dirty in side the cap allowing shorting of the HT spark

Jul 18, 2014 | Dodge Caravan Cars & Trucks

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Check engine light blinking car shaking

I would suspect that car shakes because engine is not running on all cylinders , if it moves at all i suggest getting it to someone with a code reader (shop) or if your a do it yerselfer , most national auto parts chain stores will read codes for free (ya gotta get it to there place though) just for the chance to sell ya the corect repair part

May 02, 2014 | Chevrolet Impala Cars & Trucks

1 Answer

Po306 misfire 6 cylinder

It happens a lot on all make new vehicles. Its called a "dead" cylinder. Must do an ohm meter test on all injectors and the code is saying it's #6 so that injector should read a good bit less than the others. If so, replace the injector and you should be good. If all injectors read the same on testing, then do a compression test. This will show #6 cylinder compression is less than the others with all spark plugs out for the test. If so, you must do a valve job on #6 in particular. The exhaust valve is burnt. I dislike being the bearer of bad tidings, but such is life in the automotive world. Best of luck on that first test my friend. I hope it's just the injector.

Jul 02, 2017 | Chevrolet Cars & Trucks

1 Answer

Po306 new intake gaskets smoke test compression test leak down test new plugs wires tested injectors swapped injectors checked ijjector wiring with noid still when you pull off no 6 wire it changes nothing...

Code 306 means cylinder 6 is not producing power. And as you know it takes fuel, spark, and compression at the right time to make power.
Generally, if the injector is firing at the right time the spark plug should be firing as well.
Are you sure the plug is firing ? And is it possible injector 6 has no fuel to spray ?

Sep 04, 2013 | 2001 Ford Ranger Regular Cab

2 Answers

Check engine light is on, they say multiple miss fire in cylcinder 6. but no one can find the problem van runs great

first do a cylinder compression test on engine to verify good engine compression this should be around 110psi to 175 psi check for vacuum leak, intake port for #6 cylindermay be leaking air, or also check coil for that cylinder, if wire and spark plug have already been changed, last replace fuel injector for that cylinder.

Jan 24, 2011 | 1996 Dodge Caravan

2 Answers

I have my engine light on, in my xg300 Hyundai 2001 if i replace the mass air flow sensor and my fuel air metering my light go off, Im a woman trying too fix my car my self pls help tks code...

check engine light will not go out or codes cleared till computer is cleared so if you have set off a code while trying to diagnose it will stay in memory with that in mind

PO171 & 174 are related to bank 2 lean o2 sensor reading high oxygen in exhaust at sensors
PO120 has to do with throttle position sensor input out of range
PO306 is a misfire in #6 cylinder

in my opinion any miss will cause o2 sensors to read lean because the cyl is in effect a air pump sensors only pick up o2 not the fuel does you engine run rough or hesitate/shaking on acceleration
i would check coil wire and plug for #6 also the injector not working will cause miss also they look ok do compression test on cyl will read 150psi if you find cause of miss you will be able to diagnose lean

with the tps sensor check to see if the connector was disconnected at any time you were testing

basically you need to isolate misfire and fix then have the computer cleared of codes drive car and if engine light comes on then we will go through test procedures for new codes

i hope this helps you to get a few ideals on how to proceed good luck ley me know

Jan 16, 2011 | 2001 Hyundai XG300

1 Answer

1999 V6 ford tarus turn over willl not start theft light blinks fast

Fast blink usually indicates a burned out bulb. Need to check for fuel pressure . If there is no fuel pressure could be pump., relay , fuse , wiring . Check to see if you have spark. You can use a spark plug as a tester . Pull the coil wire from the distributer insert the plug in the wire ang ground the side of the plug to the engine . Get someone to turn over the engine . You should see a bluish white spark . If not there is a problem with the ignition system .It might be easier to use one of the spark plug wires rather than the coil wire for this.
Do a vacume test . Need a vacume gauge for this. Conect it to a major vacume source on the engine and read the scale. EGR valves are a a major problem for no vacume if they stick open. If all those things are ok check compression be taking all plugs out and screwing a compression gauge into each plug hole , turn engine over and record the pressure. All cylds should be close to the same . Most gauges have indicaters as to what is to low or fair etc. If the engine light was on check for codes because some sensors can cause a no start .

Oct 22, 2010 | 1999 Ford Taurus

4 Answers

I have a ford explorer 99 but it's giving a error code PO306 what do u think it is

It sounds like a misfire. Check spark plugs 5 and 6. It could be bad fuel, bad plug wire, or weak coil. Check the fuel injectors as well. Other possible causes could be an egr valve stuck open, vacuum leaks, low fuel pressure.

Feb 17, 2010 | 1999 Ford Explorer

2 Answers

Engine runs ruff

you may have a valve or valves leaking which will cause it to run rough, have a leak down test done or a compression test

Jun 22, 2009 | 1994 Volvo 940

1 Answer

Rough running, erratic spark

Run a compression test on the cylinders.If reading is low on any drop a little engine oil into the pot. If compression rises you have compession ring problems. Remove all plugs before you try this and place leads away from engine.

Mar 04, 2009 | 2000 Ford Ranger SuperCab

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