'03 Explorer Limited V8. Code P0300 rough idle.

[Don40]

I was driving down I-5 today & the "check engine light" came on in my '03explorer. I got off the exit & noticed that when I came to a stop it was idling rough & almost shaking the whole vehicle. As I drove along, I noticed that if I put it into neutral at a stop & reved the engine, it didn't do it as bad. It's missing all of the time. It's a V8 with 120,000 miles on it. I've never changed the spark plugs or fuel filter.
I went & had it check & the code P0300 came up.
Can I get some help with this? Any suggestions where I should start?
Thanks

 

[stiffy44]

when it happen to me my check engine light was flashing I was told to take it to Ford to get the code off they will tell you what it is other garages will only know the code or will not get a code this is a ford thing they only have the right code reader too do it. .......Mine was the #7 coil it ran like you are saying good luck

 

[BobWiersema]

P0300 = Random/Multiple Cylinder Misfire Detected

I don't know if just bad plugs can cause that, but new plugs and wires would be a good place to start. Hopefully someone who has fixed it before can help you out.

Also all the error codes are posted here.
http://www.explorerforum.com/forums/showthread.php?t=228242

 

[Sams01XplrSprt]

welcome don

 

[Don40]

I changed the plugs & it didn't help at all. It's still doing it. Next, I'm going to change the fuel filter & see if that helps. Any other ideas?

 

[BobWiersema]

I changed the plugs & it didn't help at all. It's still doing it. Next, I'm going to change the fuel filter & see if that helps. Any other ideas?

Did you replace the wires?
Finish the tune up and clean the MAF , replace the PCV and Air Filter.
Am I missing anything?

Code 300 is a random misfire, no exact cylinder so it could be the coil pack to.

But finish the tune up first.

 

[1Aauto]

Welcome to the site.

 

[BrooklynBay]

Welcome to this forum! I've moved your thread into the EEC-V section.

 

[Don40]

I completed the tune up. I replaced the plugs, air filter, fuel filter. Cleaned the MAF. Its still doing it. Where is the PCV located at? My vehicle doesn't have wires. Its an 03 but I think its the 04 engine because of the production date. Any more ideas? Thanks

 

[BobWiersema]

How long has it been doing this? Any relationship to the last time you gassed it up? Bad gas would do it. If you dont think that's the problem, replace the PCV next. I think its in a valve cover on the v8 but I'm not sure. If that doesn't fix if the next thing to check for is a stuck open egr valve. Now that we know the plugs are good, with a 300 code I would almost bet its one of those two.

 

[Don40]

I had under a quarter tank of gas. I stopped & filled it up & drove home & parked it in the garage. The next day mý wife drove it a long distance. It started doing it when she was about half way to her destination. She drove it home & I began to work on it. How would I know if it is the gas? I also put a can of sea foam in. Where is the egr valve?

 

[BobWiersema]

Take a look and see if this is correct.
You got some 6gal cans laying around to siphon the gas out?

That picture was wrong, I think its in a valve cover.

Read the first page of this thread, it may help.
http://www.explorerforum.com/forums/showthread.php?t=217062

 

[Don40]

Yes the picture is the 4.0 not mine. Thank you so much for your help. I'm just not sure where its at on mine.

 

[BobWiersema]

Try this.. http://www.explorerforum.com/forums/showthread.php?t=194145&highlight=03+pcv

And dont forget this one. Read the first page of this thread, it may help.
http://www.explorerforum.com/forums/...d.php?t=217062

 

[stiffy44]

Don... I took it in they replaced the ignition firing coil they have 8 of these they replaced the wires you got too fine the one thats bad it costed me $105.00 for the part and the bill was $160.00 Canadian out the door they gave me a deal at Ford my buddy know the guy there it will be cheaper in the U.S

 

[Don40]

found pcv

I found the pcv. Its on the center of the passenger side valve cover. Its the screw in type. I went to the dealer to get one & they didn't have one in stock. We ordered it it will come tomorrow. u think mine is faulty cuz I can push & pull air through it with my mouth. Its suppose to be a one way valve as far as I know. I will update tomorrow after I install it.

 

[Don40]

I also installed a goodyear gator back belt.

 

[BobWiersema]

Let us know what happens after replacing the pcv and we will go from there.

 

[Don40]

We installed the new pcv. No change. I had it checked on my buddies new computer at his shop. This time I got a p0304 code. A misfire for the #4 cyllinder. What's the firing order? What should I do?

 

[Don40]

I just checked the #4 coil. There's a nice blue spark that comes out of it which makes me think that it's not the coil. So, I started focusing in on the noise in the back of the motor that's been there since this started. It's a pretty loud "ch ch ch" noise in time with the motor turning over. It's definitely coming from the back of the motor, the firewall side of the motor.I tried to pin point it with a stethescope, there's a metal bracket that holds up an electric sensor, it's about 4" long & 1" tall with 2 vacuum lines going into it. With the stethescope you can really hear the noise on the metal bracket that holds the vacuum/electrical sensor in place & that bracket is bolted to the plastic intake manifold.
Just to answer the question, I did not replace the egr.