Hi guys,

My 09 JCW with 76000 miles recently had a bad misfire / low power / rough idle / stalling issue with CEL light and "Engine malfunction, reduced power" light.

I took it to a mechanic and they changed the coil and spark plugs. Not much difference. They then said it could be the HPFP so I did some research and found out that I still had warranty for that (10 yrs / 120k miles). The mechanic replaced the coil back with the old ones (just in case) and I took it to the dealership.
The dealership indeed said that the HPFP was bad as well as the coil.
I explained my situation and told them I should give the coil job to my mechainc and had the dealership replace the HPFP only. When I picked up the car from the dealership, I didn't notice any changes to the car, and I thought that the coil replacement would solve the issue.

Wrong. I took the car back to the mechanic and replaced the coil again with the new ones, and the car still have the same issue. Nothing seems to gotten better at this point.
The codes I get right now are only misfire codes. I tried test driving it for few minutes and it vibrates roughly when accelerating from stop, CEL light blinks until I get to about the 3rd gear, there is no power when accelerating.

I left my car at the shop for the weekend, and the mechanic wants to open up the injector (which will cost me quite $$$) on Monday.

Does anyone has any idea what could be the issue?
I'm kinda speculating that it could be a carbon buildup, but can carbon buildup cause the car to be this bad?

Please help!

 

Really does sound like he carbon buildup to me as well. Low power and stuttering/stalling are the usual signs.

I'm surprised the dealer didn't try and get you for the walnut shell blasting at the same time they did the hpfp. It really varies in price so make sure you shop around if you end up with a lousy quote from the closet dealer.

 

If you have never had the intake ports cleaned, I am confident that is the issue after 76k miles. I would tell the dealer that you want this done (so you don't pay for 'diagnostic' fees), it should be around $400.


Mike

 

Do a compression test!

How did the spark plugs look like when you took them off?

 

Thanks for the response.
I heard that dealerships charge over $1000 for walnut blast cleaning.
I'm in North Jersey, and I called a few places and quoted me around $6~700.
Does anyone know any places around NJ / NYC area for this service with reasonable price?

As for the spark plugs, I couldn't see the old ones myself, but I was told that they were pretty dirty. The previous spark plugs replacement was about 18 months / 20K miles ago.

 

my reasoning behind the compression test is to know how much pressure you are getting. if it were tooo low, then you might be wasting money on the cleanup and the issue isnt completely a carbon build up.

 

I've got the same problem with my 2007
MCS. I did a compression test and found weak overall compression and one cylinder none. After I tore the engine all the way down I found a piston with the bottom ring land broken off. Lucky no cylinder damage.

 

Feel free to send me a PM with where you are in North Jersey and I'll pass a long a few suggestions to see who you went to. The default tends to be prestige, but they have had some huge price increases recently, although they do good work. It'll just come down to how far you want to drive.

 

Either a shop or DIY with a MINI friend.

https://www.northamericanmotoring.co...-cleaning.html

 

Reviving this thread before I start my own about a similar issue (whatever happened with this car and issue)?
I have an 08 JCW and replaced the coils and plugs about a month ago after it was running rough, and it was fixing and running good for about a month.
This weekend it started doing the same thing; weird/hard start and then really rough idle. It accelerated OK, but still not normal. (should mention that the first plugs were Bosch Plat double).
This time around, I took the coils (Duralast) back and replaced them AGAIN (more Duralast) and went with NGK R plugs and it started doing the same rough idle. Codes come back for same misfire and reco to replace the coils plugs.

People seem to really like the NGK, which why I went with those. I highly doubt out of 8 coils and 8 plugs that they all had a defective unit.
Any input, suggestions, or alternatives would be immensely appreciated. (outside of pushing it into the Mississippi river).

Thank you!

 

I just did the carbon cleaning service myself using a media blasting kit (ecs tuning and fcp euro have similar kits). Honestly the hardest thing was dealing with the hidden bolt holding the intake manifold on. The carbon cleaning itself was easy, though you do have to manually scrape some of the sticky bits away first. A bunch of zip ties in a drill works well too.

 

Here a before and after at 70kmiles. Note, I had already paid a shop to do this once before around 35k miles.