Hi there and thanks for taking the time to read this.

I have a 03 Mini with 56k.... check engine light came on and it was a engine misfire cylinder 4. ran terrible was check engine light was flashing.. not so bad when it was just illuminated

took it to my normal mechanic (not mini) and he stated that the fuel injector pulse was not constant.. when no pulse, car runs terrible etc... but he recommended that i take it to mini

went to mini, they changed the injector, no change in the way the car is running .. then they did a compression test 175 175 175 75, so low in the 4th cylinder.. i did not proceed with the $1800 head removal.

when i picked the car up, it was warm engine temp (not overheat), and the check engine light was on (not flashing).., drove about 12 miles, car ran perfect...

if the 4th cylinder had low compression, wouldnt it run terrible all the time.

i drove the car about 12 miles and it ran perfect, no stumbling

 

Do a leakdown test. That will diagnose where the compression is being lost. It is possible that a valve is intermittently sticking. Haven't heard of that happening but it is possible. The causes of low compression I have personally seen are bent valves, cracked piston, blown head gasket, burned valves. Since you are getting some compression it isn't bent or burned valves. Those resulted in zero compression in the cylinder.

 

you could bring it up to normal temp. then do a dry compression test . then a wet test (squirt a tblsp. of oil in the cyl .) and see if there's a big improvement . this will indicate a ring seal problem . if no improvement you're looking at valves . if slight improvement ; look to a leak down test and turn the crank to find the loss .

 

It is mostly likely the gasket I think. When the engine is warm the slightly damaged gasket expands a little and seal itself right? I think it makes sense...

 

Don't even waste your your energy until you do a leakdown test to find out where it is leaking. I had this happen recently, turned out to be #4 ringland broken. It drove a little rough with a deeper exhaust tone, but plenty of power until the spark plug was oil fouled enough to cause the misfire and flashing CEL.

 

Was there any follow-up with this thread? I had a similar problem over the weekend. The car was running fine at highway speeds and started missing. By the time i got to the next exit, the car started running good again. The error code came up as P0304 (miss in #4). I have a stock 02 cooper s with 100K. Thanks for any info.

 

is there any updates to this thread

 

I started with the spark plugs. I had recently placed single prong cheaper plugs in the car. I replaced these with the recommended multi-prong NGK plugs. I also switched the #3 and 4 plug wires to see if this was the issue. However, the car has not missed again (knock on wood). Not sure if the plugs were the issue but my next step will be the coil pack. Seems like it will just be a process of elimination.
I also did a compression test which was good on all 4...

 

hey guys......I took my mini in last week because the dashboard lit up like a Christmas Tree(check engine and DSC light). On the FIRST visit...it was a misfire due to bad gas and they reset the lights. That SAME evening...the lights came on again. Back to the shop we went. This was last Wednesday. I just rec'd a call this morning from the dealership and not only is it misfiring, it is losing compression. They have been consulting with the Mini Engineers and have come to the conclusion to just REPLACE THE ENGINE!!!!

I'm a little concerned due to the fact that this is a 2007 with about 20k miles on it....should I be worried about the new engine too???

 

2005 Cooper - 94 K miles

Service engine soon light on; noticeably less power.

Took to dealer yesterday - compression down in #4 cylinder

They will be taking off the head - checking/replacing the valves (or whatever) on Monday.

$$$

 

Had an '02 N/A Cooper come into the shop a few days ago with a misfire on #2. After extensive testing the customer approved a head job. Upon removal of the head I found 3 cracks in one of the exhaust valves. I've been doing a lot of research regarding this issue since and have found it to be a fairly common problem on 02-03 Minis.

Start with a dry compression test and then do a wet test. A wet test is done by adding a tspn of oil to the cylinder before checking compression. If compression is low on any given cylinder and the pressure doesn't come up to normal with the addition of oil chances are you've got a valve problem.

Off the top of my head I'm thinking compression specs are 167psi-247psi for an N/A and 145-195 cor an 'S'. But don't quote me on that.

 

Hi Guys,

I have a 2013 Mini Cooper S Coupe with 37,000 miles on it - not in factory warranty

What Happened ---> I was driving to work and all of a sudden I had a loss in power and the check engine light started flashing in Yellow. I headed back home and ran the codes and I got P0300 and P0304 which is for Cylinder 4 misfire.

What I did ---> Based on some research through this forum and youtube videos I understood that it can be either the Spark Plugs or the Ignition Coil.
To understand which of the two it was I switched out the positions of the Cylinder 3 and 4 ignition coils but I got the same codes. I then understood that it was most likely the spark plugs so I switched out all 4 of them.
The problem still persisted so I also replaced the cylinder 4 Ignition coil and the problem still persisted.

What should I do?
I am out of options and I am not a highly technical person so if you guys can help me or even point to possibilities that would be great ! if all else fails I will take it to the dealership and give them all my money. lol

Thanks guys !

 

You have posted in the Gen1 area but your car is a Gen2. Suggest you post this in the Gen2 Stock Problems/Issues area.