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Cylinder one misfire and code P0301

Tiny
JAMES ANTHONEY
  • MEMBER
  • 2001 MINI COOPER
  • 1.6L
  • 4 CYL
  • 2WD
  • MANUAL
  • 128,000 MILES
Hi, I have been experiencing problems with a P0301 code on my car listed above, after looking online it said to check spark plugs (they all look fine and we’re replaced not long ago), leads (replaced a year ago) and ignition coil. The symptoms it described would be down to an ignition coil problem is misfires, rough idle, car not starting, engine light on etc. Do you have any advice on whether this is the issue for sure? Thanks,

James
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Saturday, May 2nd, 2020 AT 1:36 AM

7 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,336 POSTS
Hi,

Do you actually feel the misfire? I ask because it could be a few things causing it. Have you checked if there is an injector maybe going bad? Have you checked compression, because low compression in that cylinder can cause a rough idle/misfire.

Let me know. Also, are the symptoms above what you are experiencing?

Joe
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Saturday, May 2nd, 2020 AT 5:47 PM
Tiny
JAMES ANTHONEY
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  • 7 POSTS
I haven’t checked compression or anything to do with fuel as I am limited on my knowledge haha! However, the symptoms we are experiencing are rough idle, engine light on, exhaust is making a sort of spluttering/puffy noise, engine stalls now and again, loss of power etc. Thanks for the reply hope this helps!
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Saturday, May 2nd, 2020 AT 5:51 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
So this is a couple possible things. Is the P0301 the only code that you have?

If it is, the best thing to do is swap things from this cylinder to number 4 and see what causes the misfire to move cylinders. Even though the plugs, wires, etc are new, you still want to swap them because they can still be the issue.

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

Basically the idea is to move things one at a time including, plug, wire, injector to number 4 and run the vehicle after each clearing the code each time and see if anything makes it go to number 4.

Let me know if you have questions. Thanks
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Saturday, May 2nd, 2020 AT 5:51 PM
Tiny
JAMES ANTHONEY
  • MEMBER
  • 7 POSTS
Yes, I had read this online and I did try a different lead in cylinder 1 and the engine light still came on, so I assumed it wasn’t the leads? And yes P0301 is the only code on the engine. Thanks for the reply!
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Saturday, May 2nd, 2020 AT 5:53 PM
Tiny
KASEKENNY
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  • 18,907 POSTS
Okay. I would try swapping the plug and injector to another cylinder and then recheck the code after each. Then go back to Joe's suggestion of compression.

A cylinder and engine for that matter need fuel, spark, and compression to run properly. If you have a signal cylinder misfire then we most likely has an issue with one of these rather then a sensor that could effect all cylinders. Thanks
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Saturday, May 2nd, 2020 AT 5:57 PM
Tiny
JAMES ANTHONEY
  • MEMBER
  • 7 POSTS
Okay, thank you for your help, would you suggest changing the ignition coil? Could that be a cause? I read something online about that? Thanks
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Saturday, May 2nd, 2020 AT 5:58 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
It could be the coil. You have what is called a coil pack so you may want to test it first. I attached that process. However, if you want to just replace it to be sure, then I would understand that because they don't appear to be too expensive.
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Sunday, May 3rd, 2020 AT 9:51 AM

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