2003 R50 Cooper - Off Idle Misfires & Hesitation [FIXED - Coil pack failing]

[markius]

Hi all

I've have a problem with my 2003 MINI Cooper that's causing it to hesitate and misfire. I've had a good search through the forums but can't find any posts that match my symptoms exactly...

I'm getting an odd hesitation/misfire at low revs when the engine is under load. It's most noticable when pulling away in 1st - unless I'm really really gentle, the car seems to die for a fraction of a second as the car begins to move. I also notice it if I'm rolling along in traffic in 2nd with the engine at about 1000 - 1250 RPM - It's fine as long as I balance the throttle and keep the speed constant, but as soon as I put my foot down to speed up, there are multiple misfires until I get to about 1750 RPM when it seems to clear.

I can make the misfire happen on demand by going up a hill at 10mph, putting the car in 5th with the engine at around 1250 RPM. If I go full throttle the car will miss and hesitate all the way up to 1750 RPM.

The car has around 95k miles on it. It's just had a new set of plugs as part of an Inspection 2 but this hasn't cured the problem.

Has anyone else had a similar problem and cured it? It's driving me crazy and making me look like a 1st year driver at roundabouts and at the lights!

Cheers
Mark

[markius]

Bump!

Just to add, although I said "misfire", nothing shows up in the ECU.

I actually think it's got worse since the new plugs went in

Can anyone help?

[Silverado]

Have a look at this thread:

http://www.mini2.com/forum/first-gen...2-misfire.html

I would initially think about a compression test on the cylinders.

[markius]

Hi Silverado

I had seen that (very scary) thread but I'd discounted the possibility of something as serious as a burnt valve because the EML has stayed off and nothing has shown up in the ECU log. Also the car idles smoothly...

I think it would be good to eliminate something that serious though so I'll get hold of a guage and report back.

Someone has also suggested that it may be a small vacuum leak somewhere. Do you have any tips on the best way to track one of those down? With the engine bay being so tight, it's quite hard to get to all of the induction system.

I'm not a mechanic but I'm willing to learn!

Mark

[daxwert]

I would have my fuelpump checked. Had a similar problem for a few months and also went into checking everything. look for an audi A4 (B6) pump, might be cheaper then the original mini.

[markius]

This turned out to be a failing coil pack.

Ordered a 2011 JCW today... not too many more first generation faults and fixes for me