Misfire..Please help!
 

I was driving home from work today and right as I turned onto my road the mini started acting funny. I could barely keep the car running long enough to get home. The CEL and Traction control lights came on. I scanned the code and came up with a p0301 which is a misfire on cylinder 1.

I changed the spark plugs, wires, and coil and then reset the ecu. Still nothing. I pulled off the wires 1 at a time and each was getting spark.

Next I took out fuel injector #1 and switched with fuel injector #4. Put the car back together and still nothing.

With the car stumbling at an idle and I pull off the plug wires 1 at a time the car does nothing while pulling of 1 and 2, but pull off 3 and 4 and the car studders. So I have narrowed the problem down to cylinders 1 and 2 but now I am lost of what to do next please help!

ps. the closest mini dealership to me is 350 miles away :sad:

Check out this link http://www.obd-codes.com/p0301 for causes and possible solutions.

If none of those solutions works for you, let us know what car you have, how many miles, any work you may have done to the car before it started acting funny, etc. so that we can help you out a little more. Good luck!

Oh yeah sorry the car is a 2002 MCS, only mods is a boost gauge, which I also checked all vacuum connections. 70k miles. Car has been running perfect since I got it, I changed the power steering pump within the first month of having it and have had no problems since. Nothing has been done to the car in the past couple of weeks. Like I said this happened out of the blue.

Maybe change the fuel filter?

Yeah thats on the to-do list for tomorrow

do compression and leak-down tests before you throw parts at it

True that, but if he's on original plugs, wires, coil and fuel filter, it's all worth changing at 70k+ miles.

JNagy, post a pic of your old fuel filter after swapping it out. Nassssty!

As to the compression and leak down, yeah there could be something there...I just hate doing those tests, always fearing the worst :no::razz:

Jan has seen a lot of problems with the exhaust value guides, but I don't know if such a problem would show up so suddenly. Way Motor Works recommend that I switch to the JCW plugs (not NGK or Denso iridium). So I did that and started using a bottle of the BMW fuel injector cleaner every 3-5k miles and it's done the trick.

I've got the NGK 7 series plugs and man my idle gets lopey at times. I haven't tried the JCW plugs, but it's near the top of the list.

well.. going in fearing the worst and came out not happy :cry:
cyl1 0psi
cyl2 155
cyl3 155
cyl4 155.

Doh! :no:

Time to talk go shopping for a new head while you're tearing things up :grin:

HAHA I wish, trying to get money together just to get it fixed :cry:

Well I sat around thinking about how much it would suck to replace rings and such. And I started to wonder why the car was showing no compression at all on that cylinder. So I took off the valve cover and what do I see.....A fat looking exhaust spring, I spin the spring around by hand and the spring is broke! Luckily the valve did not drop into the cylinder because of where the spring broke!

So relieved now that the whole motor does not need to come out and its only a 9 dollar part w00t.

thats so weird that it broke.
Glad everything ok now.

Whew...:thumbsup:

Yeah it is very weird how it broke, I was not pushing the motor at all at the time it happened, I was pretty much idling.

I was gonna say you need to do a leak-down and pull the cover before you start thinkin' of doing the bottom end, but you pulled the cover and found your problem. Glad to hear it's not something much worse.

mine broke too
 

I am in the same boat. 2003 S . not driven hard. Broken spring on intake valve.

Now I need to figure out how to replace that spring, and pray i dont have a bent/burnt valve...