Go Back   DodgeForum.com > Dodge Trucks > Dodge Dakota > 2nd Gen Dakota
Sign in using an external account
Register Forgot Password?


2nd Gen Dakota 1997 - 2004 Dakota's

Bad misfire (cylinders 1 through 4), P0300

Reply
 
 
 
 
Thread Tools Search this Thread
  #1  
Old 07-28-2014, 09:51 AM
keenerb's Avatar
keenerb keenerb is offline
Registered User
 
Join Date: Jul 2014
Posts: 22
Default Bad misfire (cylinders 1 through 4), P0300

My wife's 2003 Dodge Dakota 4.7l 4wd quad cab (unknown transmission) suddenly started misfiring badly Friday. The only engine code is a P0300.

A buddy of mine that runs a local shop is coming by this afternoon to take a look, but I figured I'd toss this out to see if anyone had any experience/similar problems/advice/etc.

I spent a little while looking over it this weekend, and noticed that it SEEMS to be missing on cylinders 1 - 4; when I disconnect the ignition coils from those cylinders, it makes no impact on how well the engine runs, but when I disconnect one of cylinders 5 - 8 the engine suffers significantly and/or dies.

I actually disconnected cylinders 1 - 4 simultaneously and there was no difference in how the engine ran.

The coolant looks good, oil looks good. Plugs and coil packs aren't that old, maybe 10,000 miles, and the plugs pretty much look like new with ~.045 gap according to my crappy Autozone gap tool. Owner's manual doesn't appear to list the proper gap, the internet says .040 is recommended. I picked up a new coil pack and swapped it out across several of the suspected "dead" cylinders and it had no impact.

My spark tester won't work with the coil packs sadly, so I haven't been able to test whether those cylinders are getting spark or not.

A few things to add that may be related/unrelated:

Exhaust is clean, no steam/smoke, other than the expected strong smell of unburnt gasoline.

There also appears to be a sudden somewhat serious oil leak from the engine somewhere around the back, passenger-side valve cover, around cylinders 6 - 8 ; I've been losing oil slowly over the last few months, so it may just be that it's aggravated by the engine thrashing itself around currently. Over the course of running the engine for a total of an hour, it looks like maybe a quarter to a half a quart of oil was lost.

About two years ago I had a cut in the wiring harnass repaired inside the driver's side wheel well that was causing a fault in emissions and rough idle. It appears to be fine, though.

I recently replaced most of my emissions-related vacuum lines inside the engine compartment, and replaced the leak detection pump and the thing behind the battery with the two vacuum lines who's name escapes me at the moment. I'm pretty sure they're hooked up correctly according to the emissions diagram on the inside of the hood, and it's been weeks since I replaced them anyway, and I had no misfire problems during that time.

It has a small exhaust manifold leak on the passenger's side which I was hoping could wait until cooler weather to fix.

This occurred immediately after picking the truck up from having four new tires installed at a local place. Normally I'd find this suspicious, but for the life of me I can't figure out how having four tires installed would cause a problem like this. Once my buddy looks at it, I'm going to call the shop and see wtf might have happened to it, but I'd like to be armed with some information first.

Thanks anyone who took the time to read through all this, I wanted to be thorough in describing the problem.
This ad is not displayed to registered and logged-in members.
Register your free account today and become a member on Dodge Forums!

Last edited by keenerb; 07-28-2014 at 10:04 AM..
Reply With Quote
  #2  
Old 07-28-2014, 10:12 AM
Dodgevity's Avatar
Dodgevity Dodgevity is offline
Veteran
 
Join Date: Oct 2013
Vehicle: 2003 Dakota
Location: Atlanta
Posts: 428
Default

Sounds like you may need to replace cam/crankshaft position sensor. I'd go with Mopar part, if I were you. Emission would probably throw a code, but not cause it run like ****, unless the cat was completely plugged.
__________________
2003 Dakota SLT
Quad Cab 4.7L - Auto -2WD - 253K
Reply With Quote
  #3  
Old 07-28-2014, 10:22 AM
keenerb's Avatar
keenerb keenerb is offline
Registered User
 
Join Date: Jul 2014
Posts: 22
Default

I had pondered whether the camshaft position sensor could be at fault, but the previous times I've had that issue the engine just wouldn't run at all.

I'll take a look at that, thanks.
Reply With Quote
  #4  
Old 07-28-2014, 10:22 AM
00DakDan's Avatar
00DakDan 00DakDan is offline
Section Moderator
Dodge Forum Moderator
 
Join Date: Dec 2010
Vehicle: 2000 Dak Sport CC 4.7 5 speed 4x4
Location: MA
Posts: 3,418
Default

Are cylinders 1-4 actually firing? Do you get a spark?

The spark plug gap should be on the emission label under the hood.

I wouldn't rule out a cam/crank sensor. They don't always trip a code. The crank sensor is on the passenger side rear, near where your oil leak is. Check the harnesses for oil.
__________________
http://dodgeforum.com/forum/signaturepics/sigpic158370_10.gif
Reply With Quote
  #5  
Old 07-28-2014, 10:33 AM
keenerb's Avatar
keenerb keenerb is offline
Registered User
 
Join Date: Jul 2014
Posts: 22
Default

Quote:
Originally Posted by 00DakDan View Post
Are cylinders 1-4 actually firing? Do you get a spark?

The spark plug gap should be on the emission label under the hood.

I wouldn't rule out a cam/crank sensor. They don't always trip a code. The crank sensor is on the passenger side rear, near where your oil leak is. Check the harnesses for oil.
Hell, I wonder if maybe that's where the oil is COMING from, based on the pictures I've found on the internet it seems to be leaking from somewhere in the very near vicinity of that spot.

I'm picking up a spark tester which will work with the coil packs today, I haven't been able to test that yet, and there is DEFINITELY oil on the harnesses in that area.

Last edited by keenerb; 07-28-2014 at 10:40 AM..
Reply With Quote
  #6  
Old 07-28-2014, 11:56 AM
Dodgevity's Avatar
Dodgevity Dodgevity is offline
Veteran
 
Join Date: Oct 2013
Vehicle: 2003 Dakota
Location: Atlanta
Posts: 428
Default

Quote:
Originally Posted by keenerb View Post
I'm picking up a spark tester which will work with the coil packs today, I haven't been able to test that yet, and there is DEFINITELY oil on the harnesses in that area.
You don't need to buy anything to test spark. Stick a plug into the boot then ground the spark plug body or threads on the manifold. You'll see it sparking (or not) when you start the car. The ole screwdriver method works too but it's just a little more exciting, especially if you're standing in a puddle.
__________________
2003 Dakota SLT
Quad Cab 4.7L - Auto -2WD - 253K

Last edited by Dodgevity; 07-28-2014 at 11:59 AM..
Reply With Quote
  #7  
Old 07-28-2014, 01:00 PM
keenerb's Avatar
keenerb keenerb is offline
Registered User
 
Join Date: Jul 2014
Posts: 22
Default

Quote:
Originally Posted by Dodgevity View Post
You don't need to buy anything to test spark. Stick a plug into the boot then ground the spark plug body or threads on the manifold. You'll see it sparking (or not) when you start the car. The ole screwdriver method works too but it's just a little more exciting, especially if you're standing in a puddle.
For some reason I thought coil packs were more complicated than that.
Reply With Quote
  #8  
Old 07-28-2014, 05:22 PM
TNtech's Avatar
TNtech TNtech is offline
Section Moderator
Dodge Forum Moderator
 
Join Date: Sep 2010
Location: Nashville, Tennessee
Posts: 2,226
SKMC69
Default

So, you're saying that all of the cylinders on one side are misfiring? Pull the valve cover on that side and start looking.
__________________
CHRYSLER-JEEP-DODGE-RAM
Master Technician
Electrical & Drivability


My Other Hobby

Last edited by TNtech; 07-28-2014 at 05:24 PM..
Reply With Quote
  #9  
Old 07-28-2014, 06:04 PM
00DakDan's Avatar
00DakDan 00DakDan is offline
Section Moderator
Dodge Forum Moderator
 
Join Date: Dec 2010
Vehicle: 2000 Dak Sport CC 4.7 5 speed 4x4
Location: MA
Posts: 3,418
Default

Good thought TN. Hopefully he knows how the cylinders are numbered.
__________________
http://dodgeforum.com/forum/signaturepics/sigpic158370_10.gif
Reply With Quote
  #10  
Old 07-28-2014, 06:48 PM
keenerb's Avatar
keenerb keenerb is offline
Registered User
 
Join Date: Jul 2014
Posts: 22
Default

Quote:
Originally Posted by TNtech View Post
So, you're saying that all of the cylinders on one side are misfiring? Pull the valve cover on that side and start looking.
no, the first two on each side, apparently. Replacing camshaft and crankshaft position sensor made no difference. I am checking spark shortly.
Reply With Quote
  #11  
Old 07-28-2014, 08:42 PM
keenerb's Avatar
keenerb keenerb is offline
Registered User
 
Join Date: Jul 2014
Posts: 22
Default

Quote:
Originally Posted by keenerb View Post
no, the first two on each side, apparently. Replacing camshaft and crankshaft position sensor made no difference. I am checking spark shortly.
WELL thanks everyone for your advice, but this story does not have a happy ending. While tracking down the source of the oil leak, I found a fairly large hole punched in the valve cover from inside the engine. My buddy took a look and found cylinder 2 has no compression, all the other cylinders are fine. The hole is right next to cylinder number 2, so obviously something catastrophic has happened.

I'll be pulling the valve cover off later this week to see what, precisely has happened. I'm not entirely sure what worst-case is for this, I imagine a crate motor is a few thousand bucks. Maybe a rocker arm just slipped off a stud or something, I'm not entirely sure how it looks under there.
Reply With Quote
  #12  
Old 07-28-2014, 08:51 PM
00DakDan's Avatar
00DakDan 00DakDan is offline
Section Moderator
Dodge Forum Moderator
 
Join Date: Dec 2010
Vehicle: 2000 Dak Sport CC 4.7 5 speed 4x4
Location: MA
Posts: 3,418
Default

A common problem is that cylinder #2 drops a valve seat, it is almost always #2. Then the cam follower falls out.

How many miles? Did it ever overheat?

Keep us posted.
__________________
http://dodgeforum.com/forum/signaturepics/sigpic158370_10.gif
Reply With Quote
  #13  
Old 07-28-2014, 09:05 PM
keenerb's Avatar
keenerb keenerb is offline
Registered User
 
Join Date: Jul 2014
Posts: 22
Default

Quote:
Originally Posted by 00DakDan View Post
A common problem is that cylinder #2 drops a valve seat, it is almost always #2. Then the cam follower falls out.

How many miles? Did it ever overheat?

Keep us posted.
It has run hot enough to sound the temperature alert chime once that I know of. It does lose some coolant at the thermostat cover, I can't figure out what's up with that, replaced it three times already.

How bad is "dropping a valve seat" and all that?

Last edited by keenerb; 07-28-2014 at 09:16 PM..
Reply With Quote
  #14  
Old 07-28-2014, 09:31 PM
00DakDan's Avatar
00DakDan 00DakDan is offline
Section Moderator
Dodge Forum Moderator
 
Join Date: Dec 2010
Vehicle: 2000 Dak Sport CC 4.7 5 speed 4x4
Location: MA
Posts: 3,418
Default

It depends...

You'll be pulling the head. The valve seat may have cracked allowing it to come out but any overheat can do it as well.

There might be some piston damage but it may not be enough to worry about.

Replace the seat and the valve if necessary. Replace the cam follower, hopefully the cam is OK.

Take some pics if you can.
__________________
http://dodgeforum.com/forum/signaturepics/sigpic158370_10.gif
Reply With Quote
  #15  
Old 07-29-2014, 09:00 AM
keenerb's Avatar
keenerb keenerb is offline
Registered User
 
Join Date: Jul 2014
Posts: 22
Default

Quote:
Originally Posted by 00DakDan View Post
It depends...
Doesn't it always...

Quote:

You'll be pulling the head. The valve seat may have cracked allowing it to come out but any overheat can do it as well.

There might be some piston damage but it may not be enough to worry about.

Replace the seat and the valve if necessary. Replace the cam follower, hopefully the cam is OK.

Take some pics if you can.
Here's the hole in the valve cover. I don't have much else to offer at the moment. I'll be removing the valve cover this evening or tomorrow evening, as time permits.

Click the image to open in full size.
Attached Images
File Type: jpg oJ8UJ2G.jpg (58.0 KB, 18 views)

Last edited by keenerb; 07-29-2014 at 09:08 AM..
Reply With Quote
  #16  
Old 07-29-2014, 09:48 AM
00DakDan's Avatar
00DakDan 00DakDan is offline
Section Moderator
Dodge Forum Moderator
 
Join Date: Dec 2010
Vehicle: 2000 Dak Sport CC 4.7 5 speed 4x4
Location: MA
Posts: 3,418
Default

You might get lucky and it's just the follower.
__________________
http://dodgeforum.com/forum/signaturepics/sigpic158370_10.gif
Reply With Quote
  #17  
Old 07-29-2014, 09:53 AM
keenerb's Avatar
keenerb keenerb is offline
Registered User
 
Join Date: Jul 2014
Posts: 22
Default

Quote:
Originally Posted by 00DakDan View Post
You might get lucky and it's just the follower.
Yeah, I'm actually not TOO worried. Even though we're expecting some downtime with the truck at this point, she's still got something to drive to work and back. I've never pulled a head, but I love working on cars, so I'm honestly looking forwards to it just a little bit.

My mechanic friend thinks it's the rocker arm, so we'll see.
Reply With Quote
  #18  
Old 07-29-2014, 10:42 AM
keenerb's Avatar
keenerb keenerb is offline
Registered User
 
Join Date: Jul 2014
Posts: 22
Default

If the rocker arm had popped out, shouldn't I still have compression? There's no compression in that cylinder.
Reply With Quote
  #19  
Old 07-29-2014, 10:52 AM
Dodgevity's Avatar
Dodgevity Dodgevity is offline
Veteran
 
Join Date: Oct 2013
Vehicle: 2003 Dakota
Location: Atlanta
Posts: 428
Default

Quote:
Originally Posted by keenerb View Post
It does lose some coolant at the thermostat cover, I can't figure out what's up with that, replaced it three times already.
Well, too bad it wasn't an easy fix but sounds like you'll have fun wrenching on it.

I assume you mean the radiator cap above? The thermostat sits underneath on the 4.7L. If you've replaced the cap and it still leaks at the neck, there may be a crack or wear, preventing a seal. JB weld can sometimes get you by but a replacement may be in order.

Edit... just remembered that the upper radiator hose is where the "neck" is located and not on the actual radiator. Not near my truck to see right now, but maybe you can just replace the T-junction/filler neck?
__________________
2003 Dakota SLT
Quad Cab 4.7L - Auto -2WD - 253K

Last edited by Dodgevity; 07-29-2014 at 10:56 AM..
Reply With Quote
  #20  
Old 07-29-2014, 11:03 AM
keenerb's Avatar
keenerb keenerb is offline
Registered User
 
Join Date: Jul 2014
Posts: 22
Default

Quote:
Originally Posted by Dodgevity View Post
Well, too bad it wasn't an easy fix but sounds like you'll have fun wrenching on it.

I assume you mean the radiator cap above? The thermostat sits underneath on the 4.7L. If you've replaced the cap and it still leaks at the neck, there may be a crack or wear, preventing a seal. JB weld can sometimes get you by but a replacement may be in order.

Edit... just remembered that the upper radiator hose is where the "neck" is located and not on the actual radiator. Not near my truck to see right now, but maybe you can just replace the T-junction/filler neck?
it leaks around the thermostat housing on the bottom passenger side of the engine. No idea why, the surface is perfectly flat, clean, and new housing and thermostat always leaks. I must be doing something horribly wrong. Maybe over-tightening it.
Reply With Quote
Old 07-29-2014, 11:03 AM
 
 
 
Reply




Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Forum Jump

Join DodgeForum
Advertising

Featured Sponsors
Vendor Directory
Our Sponsors
All times are GMT -4. The time now is 03:23 AM.

Internet Brands, Inc.


Contact Details & Emails