Hi guys,

i have an issue with my 03 JCW. The car has been underperforming at low rpm for a while and i cant get off the mark very quick, some say it could be timing? Every now and then she idles weirdly and when my Dad drove it he nearly stalled at first and she struggled to recover the rpms. Today which was very hot the car just cut out and struggled to start a few times. Could this all be related to timing or are there other factors at work?

The car is stock, apart from decatted and a different air filter.

Thanks

 

Any error codes?

 

The car may not throw a code if timing is only off by a tooth. Do you get a rattle that lasts longer than 2-3 seconds on cold startup? If so your tensioner may be sticking and there is a small chance the chain could have skipped a tooth. This is unlikely unless you are getting this rattle.
Other possibilities are vacuum leak or a torn supercharger intercooler boot (boost leak), spark plugs, dirty air filter, dirty fuel filter, bad tank of fuel, regular 87 octane instead of premium fuel, slipping belt, sticking bypass valve, fouled or bad mass air flow sensor, etc. Some of these will throw codes, others won't.

 

Im taking in the car to BMW tomorrow to get a full diagnosis on everything. My traction control light came on again for the 3rd time and the car was jerking around today so BMW better solve the problem, this is the 3rd time it will be with them

 

ok thanks so much man i will ask them to check everything you have mentioned and anything else that their is left. Hope they sort it out, thanks

 

So BMW called today and said that whoever replaced the cylinder head put the wrong spark plugs in, so thats one issue. the to other my supercharger boot needs replacing, however they say that they need to order the sparkplugs from germany? is this true? what sparkplugs does the r53 jcw take?

 

Wow. A torn boot would definitely cause this. Plugs, not so much but they still should be replaced for the correct specification plugs to avoid any early detonation or plug temperature issues.

Sounds like a good diagnosis but with a "Cadillac" solution.
You don't need to go all the way to Germany for spark plugs for this car.
This NAM thread is a discussion on JCW plugs.
https://www.northamericanmotoring.co...ark-plugs.html

Both plugs and intercooler boots are very easy to replace, certainly not something I think you should be paying $140 per hour in labor. If you don't know how to do this yourself, any decent independent shop with MINI or euro car experience should be able to do both in under 30 minutes.

 

Is there a thread showing how i can do it? Over here in South Africa they overall want to charge $500 for the job. Would the plugs cause the low end power problems in heat? It gets extremely hot here in Cape Town, 30-40 degrees centigrade in the day

 

I might be able to make a video tomorrow to show you how to do this.
Do you need help with how to change plugs as well or just how to change the boots?

 

Sorry man i have been very busy and wasnt able to reply but i have the car back and to be honest i cant really see a differnece in low end power at all. Car still jerks back and forth if im in traffic between 1700rpm and 2200rpm it jerks up and down and up and down on its own. The take off is maybe marginally better but otherwise cant tell anything new

 

What work was done?
Sounds like you might have a bad bypass valve, an issue with early 2004 and earlier R53s. A Detroit Tuned bypass valve might be your answer.

 

Ah thats exactly what they just replaced, new shut off or bypass valve and i got a new set of JCW spark plugs. i do however know that my engine mounts need replacing urgently so could this aggravate the jerking problem?