2008 Ford Explorer misfire.

70

Asked by GuruD5CSK Aug 10, 2017 at 06:14 PM about the 2008 Ford Explorer XLT

Question type: Maintenance & Repair

I have a 2008 explorer with a 4.0. I recently purchased it for my daughters college car. I knew it need some work but didn't expect to struggle to fix like I have.
Misfire codes P0306
Replaced the following:
Spark Plugs
Plug Wires
Coil
ECM
Intake Gaskets
I'm at a loss and have thrown enough parts at this thing.
Thanks in advance for the help!!

31 Answers

324,795

Did you clear the code after replacing all those parts?

2 people found this helpful.
70

Yes. Cleared all the codes. Before replacing the ECM.

1 people found this helpful.
15,790

Have you looked at fuel delivery? Fuel psi? Injector on cylinder 6? Leak down on cylinder 6? Compression on #6?

324,795

Definitely check the compression before throwing more parts at it.

2 people found this helpful.
70

Yes. Thanks for reminding me. Also replaced #6 injector, compression and leak down test. Also checked all wiring back to the ECM

1 people found this helpful.
70

Fuel delivery seems fine. Checked injector spray when I had the rail off.

70

I have Spark, Fuel, and Air. I'm at a loss....

1 people found this helpful.
324,795

You could try swapping out parts to see if the trouble stays at #6 or moves with the part.

2 people found this helpful.
324,795

I know this probably has nothing new for you but if it helps you then great ------ https://www.yourmechanic.com/article/p0306-obd-ii- trouble-code-cylinder-6-misfire-detected-by-jay-safford

15,790

Any vacuum lines or pcv close to this cylinder? We're all your psi readings in spec? Borderline can cause issues. Any arcing inside plug well on #6?

1 people found this helpful.
15,790

Did you put on a new O-ring on new injector? All of them? You could be losing psi on dry O-rings

324,795

Buying a device that hooks up to the OBD2 port that gives you live data might be the next step. Something like this ----- http://www.auterraweb.com/

1 people found this helpful.
70

To further explain. The misfire code PO306 was stored, the engine light is on at idle, and while driving the engine light flashes. It has a rough idle and extremely rough in OD at highway speeds.

15,790

Flashing light is bad. It means that you are in jeopardy of ruining your catalytic converters if driven like this. Raw fuel getting down that far without being burned. Yes buy a live data scanner to monitor different systems. Harbor freight has a cheap one but autel is a good brand. I have 2 autels and a harbor freight one. Any O2 sensor codes?

1 people found this helpful.
Best Answer Mark helpful
70

Live data device it is. I will get one ordered. What exactly should I look for as far as data? Thanks F_O_R & Guru9FSV8. If y'all think of anything else please let me know.

70

It had no lean codes or O2 codes. Just Random misfire P0300 and #6 P03006

1 people found this helpful.
70

Any thoughts on it being an issue with the crankshaft sensor?

1 people found this helpful.
15,790

P300 is almost always fuel related! Look at short term and long term fuel trims and oxygen sensor activity with engine at operating temp. There are a lot of good YouTube videos on how to read live data and misfires. Wells automotive has good ones

3 people found this helpful.
15,790

Almost sounds like a good sized vacuum leak causing you ECM to overcompensate and pour in the fuel...hence the flashing check engine light and unburned fuel getting downstream.

70

Could be.... AC is stuck in defrost mode. Vacuum controlled I think.

15,790

Using fuel trims to determine type of misfire by scanner danner on YouTube is a good video. I want to say gasket leak. You said you replaced manifold gasket. Are you sure it sealed? Fel Pro gaskets are good. This goes along with vacuum leak like I said earlier

2 people found this helpful.
70

Ill check it out. Yep, I even pulled the intake back off to verify. Everything looks good. When I get the live data scanner hopefully some questions will be answered.

324,795

A flashing light on Fords means that a code is pending at least on the two I own. I would look at fuel trims like others have already mentioned. One possible source of a hidden vacuum leak may be behind the battery box. On my Fords the vacuum tank is on the back side of the battery box next the the fender and on my F150 the vacuum hose rotted off at the tank which is totally hidden from view.

30

Oh man, I have exact same symptoms but on cylinder 2. Replaced spark plug, spark plug wire, gnition coil pack and fuel injector. Mechanic thinks it's pcm. He said he checked wires from pcm to fuel injector. He said he ran multimeter on fuel injector leads and could see it losing signal periodically. Did you ever get yours fixed???

70

Yes. After throwing a bunch of parts at it I finally figured it out. That was two years ago and she has been driving it ever since with no issues. It turned out to be a broken valve spring. $5.00 part

2 people found this helpful.
30

May God shine kindly on you, sir! I pray that's the same for me... I'll find out this weekend? Was it difficult to change out? I've never been that deep in an engine before. Plenty of YouTube vids though...

30

For others experiencing similar issues... I did and do not have a broken valve spring. I did find the connecting wires to my EGR had a spot where all the wires sheathing was worn off and those wires were touching. I fixed that. I replaced my EGR and cleaned my intake. While doing this work my battery cable was disconnected. I drove many problem free miles over the next couple of days. However, slowly but surely the problem re-arose. Its very odd. It makes me think it's something electronic.

1 people found this helpful.
30

Or possibly vacuum hose related

1 people found this helpful.

Your Answer:

Explorer

Looking for a Used Explorer in your area?

CarGurus has 2,102 nationwide Explorer listings starting at $3,995.

Postal Code:

Ford Explorer Experts

  • #1
    OJ
    Reputation
    24,090
  • #2
    TransAm77
    Reputation
    6,020
  • #3
    G A Arne
    Reputation
    5,580
View All

Find great deals from top-rated dealers

Search

Related Models For Sale

Used Ford F-150
97 Great Deals out of 7,106 listings starting at $1,009
Used Ford Expedition
8 Great Deals out of 479 listings starting at $2,639
Used Jeep Grand Cherokee
56 Great Deals out of 3,500 listings starting at $2,900
Used Chevrolet Tahoe
9 Great Deals out of 308 listings starting at $2,500
Used Ford Edge
49 Great Deals out of 2,852 listings starting at $4,400
Used Dodge Durango
43 Great Deals out of 924 listings starting at $3,900
Used Toyota 4Runner
9 Great Deals out of 459 listings starting at $6,988
Used Toyota Highlander
19 Great Deals out of 1,745 listings starting at $1,840
Used GMC Acadia
36 Great Deals out of 1,274 listings starting at $4,999
Used Ford Escape
150 Great Deals out of 6,014 listings starting at $1,995
Used Chevrolet Traverse
17 Great Deals out of 1,380 listings starting at $5,250
Used Honda Pilot
17 Great Deals out of 781 listings starting at $509
Used GMC Yukon
11 Great Deals out of 511 listings starting at $699
Used Chevrolet Silverado 1500
69 Great Deals out of 4,207 listings starting at $2,000
Used Nissan Pathfinder
29 Great Deals out of 1,134 listings starting at $121

Used Cars For Sale

2017 Ford Explorer XLT For Sale
6 listings starting at $24,899
2016 Ford Explorer XLT For Sale
4 listings starting at $20,995

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use. Content will be removed if CarGurus becomes aware that it violates our policies.