P0301 trouble code will not pass smog test

Tiny
CARPETMAN1759
  • MEMBER
  • 2005 DODGE CARAVAN
  • 3.8L
  • V6
  • 2WD
  • AUTOMATIC
  • 220,000 MILES
Misfire at plug number one. Changed plugs, wires and coil pack. What else can it be? Changed plugs around to make sure I did not get a bad plug and also did it with the wires also. What should be my next step? Thanks for any help you can give me!
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Thursday, October 5th, 2017 AT 1:36 PM

17 Replies

Tiny
HEYMAN1104
  • EXPERT
There are a lot of things that can cause a misfire code. Plugs, wires, and coils are probably the most popular. But you could also be looking at a clogged/sticking fuel injector, a cracked piston (less likely but I have seen it), a leaky intake gasket (even less likely), and a bad PCV valve.

I would look into the fuel injector, myself. Here is a nice how-to guide on checking them: https://www.2carpros.com/articles/how-to-test-a-fuel-injector

If you have not replaced the PCV lately, you might as well go ahead and do it. It wil cost you about $5.00 and take you about two minutes to replace it. Check YouTube for vehicle specific instructions if you cannot see it.
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Thursday, October 5th, 2017 AT 2:51 PM
Tiny
CARPETMAN1759
  • MEMBER
The "how to check" site comes up as a error. I would like to clean the injectors first. Of coarse you have to take the top of the intake off to get to the injectors.
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Thursday, October 5th, 2017 AT 3:37 PM
Tiny
HEYMAN1104
  • EXPERT
Arghhh! Try this: https://www.2carpros.com/articles/how-to-test-a-fuel-injector

And I definitely understand not wanting to pull the upper intake off just to check a fuel injector. If you're going to try injector cleaner, I suggest the Lucas brand one (available at the local parts store). Put that stuff in with about a 1/2 tank of premium gas (preferably shell or BP, something with a lot of cleaning junk in it). Take that car for a ride, and open the throttle up a few times, without getting a ticket, that is.

If your problem is a sticking or clogged injector, this is probably your best shot at cleaning it out without taking that intake off and replacing it. This has worked for me a couple of times.

It's also a possibility that you've lost some compression in that cylinder. You can get a compression tester from AutoZone or another parts shop and check it against the other cylinders on that bank. Here's another guide: https://www.2carpros.com/articles/how-to-test-engine-compression

Good luck and let us know what you find.
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Thursday, October 5th, 2017 AT 7:28 PM
Tiny
CARPETMAN1759
  • MEMBER
I hate to be a pain, but is there a injector cleaner you can hook up to the fuel rail to help clean the injectors? I have tried the cleaner in the tank many times and it makes it run better. I cannot get to the number one injector without pulling the intake on this model. I guess I can do the compression test next and if that is bad then it is game over. If the compression is good it is time to pull the intake. That is the real argh! Thanks for your time for me!
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Friday, October 6th, 2017 AT 6:17 AM
Tiny
HEYMAN1104
  • EXPERT
I have never seen anything like that myself. I suspect any product like that would do great at cleaning the rail out, but would not do a bit of good for the injectors themselves.

And honestly, I doubt your problem is a compression related issue. It is possible, but just does not "feel" right to me.
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Friday, October 6th, 2017 AT 3:33 PM
Tiny
CARPETMAN1759
  • MEMBER
Now this engine has 220,000 miles on it and has the factory PVC valve in it. But what I have seen I would have to remove the valve cover to get this thing out of the hole. I am sure it is cooked in there by now. This is a family members car so I do not have it in front of me, but the van is in really good shape. Also, the compression was great for all six cylinders. I was hoping there was a way to hook up a cleaner to the valve on the fuel rail, which to clean the injectors out. Getting this Caravan dropped off with me in four days and will start pulling it apart. Will start with the PVC valve and go from there. I know I will end up pulling the intake and changing the injector. Will I need to pull the whole intake or can I get away with just the top half?
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Saturday, October 7th, 2017 AT 7:42 AM
Tiny
KEN
  • ADMIN
If I can step in and help I would check to see if the coil is getting signal from the PCM I have seen where the coil drive burns out and it does trigger the coil.

Here is a guide check it out and get back to us please.

https://www.2carpros.com/articles/how-to-test-an-ignition-system

Please let us know what happens.

Cheers, Ken
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Tuesday, October 10th, 2017 AT 11:19 AM
Tiny
HEYMAN1104
  • EXPERT
Yeah good thinking Ken. Definitely worth checking.
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Tuesday, October 10th, 2017 AT 12:19 PM
Tiny
CARPETMAN1759
  • MEMBER
Ken, Thank you for your input! This van has a single coil pack with six towers on it that goes to each plug itself. I guess it will have a plug going to the coil that has six different wires? So I will need to check them out also? I have no diagram for the wiring at all for the 3.8L dodge.
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Tuesday, October 10th, 2017 AT 2:32 PM
Tiny
HEYMAN1104
  • EXPERT
I'd take a spark tester and just hook it up between the coil and plug wire for each cylinder. Compare the sparks coming out. Here's the spark tester that I use: https://www.amazon.com/Lisle-20610-Inline-Spark-Tester/dp/B0002STSC6/ref=sr_1_1?ie=UTF8&qid=1507690227&sr=8-1&keywords=lisle+spark+tester

They do sell them at the various auto parts stores as well. But Amazon is a little cheaper, as usual. Hope that helps you.
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Tuesday, October 10th, 2017 AT 7:51 PM
Tiny
CARPETMAN1759
  • MEMBER
The thing is all six cylinders fire. I used an old style timing light that hooks between the wire and the plug. It shows me the light is as bright on plug one as it is on the rest of them. On this P0301 code, should I be looking for a electrical or a fuel delivery problem or both? I am getting this van later today and will start on it tomorrow morning. Would like to know where to start? Should I start at the wires coming into the coil pack or go for the injector? I know how to test the four wires that go into the coil pack.
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Wednesday, October 11th, 2017 AT 7:31 AM
Tiny
KEN
  • ADMIN
I would do the compression test to make sure we are not chasing a low compression issue on one or more of the cylinders. Can you make short video of the engine running so we can see? Upload it to the site would really help us.
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Wednesday, October 11th, 2017 AT 10:04 AM
Tiny
CARPETMAN1759
  • MEMBER
I am an old car mechanic and no nothing about making a video. I own a flip-phone that does not take pictures. Did a compression test and all six cylinders are within five lb of one an other. You can't feel the miss. It just makes a "putt" noise at idle thru the exhaust. I clear the code and it takes driving one hundred feet down the road for the light to come back on. I have done this five times now an the light comes on at the same time every time.
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Wednesday, October 11th, 2017 AT 11:43 AM
Tiny
KEN
  • ADMIN
The putt from the exhaust says ignition crossfire or leaky exhaust valve. Are you using OEM ignition parts wires etc?
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Thursday, October 12th, 2017 AT 10:28 AM
Tiny
CARPETMAN1759
  • MEMBER
Yes I am! If it was a injector problem, how would the computer pick up the miss-fire code? I would think it would be more on the electrical side of the injector then the fuel delivery part of the injector? That should tell me to check the signals going into the coil pack? But if the signal is bad shouldn't I get a trouble code for miss-fire on plug four? Seeing they use the same signal wire to the coil. I could be chasing this thing for days!
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Thursday, October 12th, 2017 AT 11:01 AM
Tiny
KEN
  • ADMIN
It may or may not catch a signal error. When a cylinder misfires the voltage to fire the plug is different that's how the computer can tell what cylinder is misfiring. I am wondering if you have a flat cam which can cause the problem as well.

Here is a guide that should shed some light on the situation.

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

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Thursday, October 12th, 2017 AT 11:07 AM
Tiny
CARPETMAN1759
  • MEMBER
Ken, Thank you for your time and the input! It has been raining here and I have one car in the garage already. I will start checking everything you pointed out and get back to you. Thanks!
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Thursday, October 12th, 2017 AT 2:54 PM

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