Rough running, backfires

Tiny
KIM KELLER
  • MEMBER
  • 2003 DODGE CARAVAN
  • 3.3L
  • V6
  • 2WD
  • AUTOMATIC
  • 215,000 MILES
Out of the blue, started engine and was idling rough. Went for a drive and it sputtered and backfired. Not wanting to accelerate. Had mechanic check it, said various misfires. Changed plugs, then coil pack. Diagnostic said fuel injector #6. Change that, didn't help. Diagnostic then said electronics to injector. My mechanic sent it to an electric man who said he traced the problem to the ECU. While I was looking for ECU's a fried of mine said it wouldn't be the ECU because the car still runs. Makes sense to me. What do I do?
Monday, September 30th, 2019 AT 4:22 AM

10 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Hi,

I would agree that the ECM is most likely not the cause.

Here is a guide that will take you through the most common causes of backfiring:

https://www.2carpros.com/articles/engine-backfires-while-running

https://youtu.be/HiI_eeFg-2A

I know you said it just started but have had any services done recently?

Did they find any codes when they were looking at the vehicle?

Let me know this and review these guides and we can go from there. Thanks
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Monday, September 30th, 2019 AT 6:37 PM
Tiny
KIM KELLER
  • MEMBER
  • 6 POSTS
Thanks for responding! The only thing I have had done is an oil change a couple of months ago. Really she has always purred like a kitten! I will go to AutoZone tomorrow and see what the codes say now and get a printout. Thanks for the suggestions, I will be in touch soon.
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Monday, September 30th, 2019 AT 11:24 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Sounds good. Just let us know what you find and we can go from there. Thanks
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Tuesday, October 1st, 2019 AT 4:10 PM
Tiny
KIM KELLER
  • MEMBER
  • 6 POSTS
AutoZone codes say: random misfires detected, manifold absolute pressure BARO sensor high input, injector circuit open-cylinder 6, Cylinder 1 & 6 misfire. The guy at AutoZone said to change the wires. When they changed the plugs they did not change the wires. What do you think?
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Tuesday, October 1st, 2019 AT 5:24 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
That may address the misfire codes but not the others. Can you send me the actual codes and I will see if there is a common denominator? I don't need the misfire codes because I know those are P0300, P0301 and P0306. But what are the others because the MAP and BARO can cause a P0300.

Plus the injector code for number 6 will cause the misfire on cylinder 6 so wires will not fix that one. More than likely they just wanted to sell you something. That is why they offer the free service of pulling codes. They want you to come to them so they can try and sell the most likely part they think it could be.

Thanks
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Wednesday, October 2nd, 2019 AT 7:36 PM
Tiny
KIM KELLER
  • MEMBER
  • 6 POSTS
Thank you, the codes are P0108, P0206. You are indeed correct on the other codes. Hope you can guide me to the real problem.
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Wednesday, October 2nd, 2019 AT 10:16 PM
Tiny
KIM KELLER
  • MEMBER
  • 6 POSTS
I have some additional information for you. I am not the mechanic, my friend is. So I may not know the part names but I will try to be clear. After my regular mechanic replaced the coil pack, he reached behind it and found that the plug with a bunch of wires was disconnected and hanging there. The other end was laying on hot exhaust and there was a small area where the insulation on it was burned. He tried to reattach the plug but the little tabs were worn and would not make a snap on connection. He put a zip tie on it so that it would stay plugged in. I asked him if the plug, not being plugged in might have been the original problem, he said no. His diagnostics said the #6 injector needed to be replaced. He did that but no change. That's when his diagnostics said some kind of electrical problem with #6 injector. He then sent it to his electrical man who said he traced the problem to the ECU
Don't know if that helps. Thank you!
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Wednesday, October 2nd, 2019 AT 11:58 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Okay. It could be the ECU that is not firing the injector however, I would wonder what the electrical specialist did with the wiring. If there were melted wiring found that is where I would start. I understand they zip tied the connector back together but this is not a sufficient repair. If it were me not only would I want them to replace those connectors but they need to test resistance in all of those wires. I suspect there is a wiring issue for that injector and each of those other codes. I just wouldn't want to see them put a module in it and it still does not fix it. Unfortunately it happens too often.

If you want to "test" them. Ask "what the resistance measurement was for each of the wires for the injectors and those that were melted." Proper resistance should be measured in Ohms and be less than a half ohm for a single wire. If they say they were "good" I would press them to make sure they actually checked each one. If they haven't then I would do the module until that is done. Otherwise, you could be wasting your money on a module.

Let me know if you have questions. Thanks
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Thursday, October 3rd, 2019 AT 7:56 PM
Tiny
KIM KELLER
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Alright, I will check on the electrical issue. Then see where to go from there. Thanks so much for your time and help. I will let you know what happens.
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Thursday, October 3rd, 2019 AT 8:21 PM
Tiny
KASEKENNY
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Sounds good. I will wait to hear back. Thanks
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Thursday, October 3rd, 2019 AT 8:39 PM

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