2005 Dodge Ram cylinder coils

Tiny
RONLILIE
  • MEMBER
  • 2005 DODGE RAM
  • V8
  • 2WD
  • AUTOMATIC
  • 146,000 MILES
Truck was dying out, put on computer, cause was EGR valve. Changed out, truck ran better, but missing. Put on computer, showed multiple misfires. Cyl. 3 & 7. Had dealer replace them for about $300.00. Lasted two weeks, started missing, showed #7 again. I bought coil for 25.00, replaced, ran great for three days. #7 bad again. Replaced again, ran great two days, missing again. #7 out again. What can it be? I find no visible signs of a short, and will still check for a pinched wire at EGR valve, but I do not think that is it. EGR valve IS hard to reach though.
Thursday, July 23rd, 2009 AT 8:48 AM

10 Replies

Tiny
RACEFAN966
  • MECHANIC
  • 5,029 POSTS
OK if you would call you local parts stores and see if one does a free scan and scan it write the codes down and then have them clear them and get back to me with the codes. I need the P? Codes so I can help you with this problem. Get back to me with that and we will go from there.
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Thursday, July 23rd, 2009 AT 10:25 AM
Tiny
RONLILIE
  • MEMBER
  • 6 POSTS
I will stop by Auto Zone and get the P? Codes for you.
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Thursday, July 23rd, 2009 AT 12:46 PM
Tiny
RONLILIE
  • MEMBER
  • 6 POSTS
O.K. Codes are as follows:
P0300- Multiple Mis-fires and P-0303 Cylinder 3 mis-fire
________________________________________
Now, to recap. The first time it started running bad, after I replaced the EGR Valve and spark plugs, the codes said multiple misfires (P0300), P0303, P0307
I took it to the dealer, who said coils were bad on cyl 3 & 7. Replaced them, two weeks later problem returns, checked and it was Cyl 7 again. Replaced coil, ran good three days, then problem returned, showed Po307, cyl 7 Replaced coil again, ran good two days, not running terrible again, and the new codes are as listed at top pf e-mail. Someone said it might be the Bosch spark plugs? Doesn't sound right. And why is it always 3 or 7 ( mostly 7) that craters?
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Friday, July 24th, 2009 AT 9:04 AM
Tiny
RACEFAN966
  • MECHANIC
  • 5,029 POSTS
OK it could be the plugs it could be the coils again or it could be the injectors. The codes say it is a missfire but not what is causing it so that is up to us to figure out now. So pull the plugs and check them if they look questionable then go back to the factory plug which it champion plugs and get the platnum ones ok. Now as for the injectors and coils lets do an ohms test on them. Coils should be checked at 70 to 80 degrees and if you unplug them the resistance should be between terms.6 to.9 ohms. Now the injectors just unplug them and check ohms across the injector terms and let me know what you find for ohms here. Also check the coil on boot for ohms of resistance and let me know how they ohm out. Now if this all checks out then I would like to check the auto shut down relay circuit and I also need to know what engine you truck has. Get back to me with what you find.
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Friday, July 24th, 2009 AT 9:41 AM
Tiny
RONLILIE
  • MEMBER
  • 6 POSTS
O.K, this is not out of my league. But I do have a few questions. Oh yeah, the engine is a 4.7 liter. Thought I put that in the subject line before, maybe not.
1. I put Bosch platinum plugs in less than 5 months ago. Why would a Champion be different or better?
2. If it would be an injector, why does a new coil fix it for a time?

I do not have experience checking ohms on coils or injectors.
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Friday, July 24th, 2009 AT 12:14 PM
Tiny
RACEFAN966
  • MECHANIC
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Ok I never assume that because one thing fixes it for short time that the problem is alway's the same. These are what can cause an engine missfire and as a mechanic I diagnos twice and replace once I don't like come backs unless it is for another problem not the same problem. Now that I have the engine size I can look up the proper resistance for you when you get me the ohm's of resistance on the coils and injetors. Now to check the resistance you need a digital multi meter and you set it on the 2K scale and then you unplug the coil and hook up the meter between the terminals on the coil itself (not the wire harness) and let me know what it reads. Then do the same on the injectors. I would check each cylinder sense you are getting a P0300 code. Now as far as using champions over bosch it is like this. The Dodge used champions from the factory so as I see it that is what plug the factory tuned the ignition to so it should work best. Also I have used bosch in my Mustang and my other cars figuring it was an inexpensive platinum plug and and developed a P0300 code in each pull the plugs and went back to factory type plug (autolite in this case) and problem solved so this proved my thoughts on this. I now run E-3 diamond fire plugs and they are working great better mileage and power and no missing but they are not cheap they cost like 7 dollars a plug. I hope this helps explain why I use the factory type plug. Get back to me with coil and injector test and we will go from there. I may need you to pull the two coils that you replaced to check the boots on the end of them again you will check the resistance of them. Let me know what you find.
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Saturday, July 25th, 2009 AT 9:22 AM
Tiny
RONLILIE
  • MEMBER
  • 6 POSTS
O.K, that explains a lot. I will need to get a meter and then I will let you know. I see that the Bosch plugs on 3 & 7 have burn marks down the side, from top of plug to base. I replaced these two plugs with Autolites ( the parts store did not have Champions) and I replaced # 3 coild. Ran great Staurday and Sunday, barely made it to work this morning. I have not had time to check codes again. I believe I need to change out all plugs at this point, and perhaps a coil or two.
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Monday, July 27th, 2009 AT 8:32 AM
Tiny
RACEFAN966
  • MECHANIC
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Ok after you change the plugs and get the codes get back to me with that and let me know what the ohms are on the coils and the injectors and we will take it from there.
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Tuesday, July 28th, 2009 AT 9:15 AM
Tiny
RONLILIE
  • MEMBER
  • 6 POSTS
I changed out all plugs, put in Champions, replaced one more burned coil, and it is running great so far. Only been a day though, so we will see. If it does it again, I will ohm it and send that info to you.
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Tuesday, July 28th, 2009 AT 9:53 AM
Tiny
RACEFAN966
  • MECHANIC
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Ok that sounds good.
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Wednesday, July 29th, 2009 AT 9:08 AM

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