Hi

I've had a search through the forums to see whether anyone else has had this problem but currently I've not found exactly the same symptoms.

I have a 2002 R53 Cooper S with 108K miles.
When accelerating using gradual acceleration, when you reach about half to two thirds throttle, between 3500-6000 rpm the engine will stutter quite a lot. The acceleration is not smooth! It is really noticeable in gears 2 to 4. Not very noticeable in the upper gears. It will continue to stutter through gradual throttle application.

HOWEVER, what is really strange is that the car does not stutter at all in any gear at any revs when using Full Throttle. It pulls really smoothly and with a lot of power.

I will also behaves fine when driving with lower revs and keeping a steady speed (urban driving). It's just when having to apply some extra throttle (not full throttle) that you really start to notice it.

I believe this is affecting the fuel consumption, however that is probably because I'm driving with full throttle more!! ;-)

To try and solve the problem I have done the following:
New Spark Plugs, K&N Panel filter, HT Leads and MAP sensor.

I haven't changed the T-MAP sensor.

Car has no modifications, all stock (apart from K&N panel filter).

Please help! Has anyone seen these exact symptoms before and if so how did they resolve them?

cheers

 

I would guess the injectors are starting to show signs of age... minor build up in the injectors not giving you a smooth flow of injection under less then full throttle.

A couple of things you can try... I'll start with the most expensive...

Replace the injectors but at around $122.00 each this is expensive ($488.00 + a set)

Ultra sonic injector cleaning service, this runs about $20.00 per injector and even with postage is cheaper than replacing one (1) for new.

And of course using a product like "CRC 1 Tank Power Renew" which runs about $17.00 at your local auto parts store. One bottle treats 25 gallons so you could run two tanks of treated fuel and easily compare the results.

(I do not have any affiliation with CRC, I like their products and they were originally from Pennsylvania)

Best of luck no matter what you decide to do.

Motor on!

 

Thanks for the quick reply James.

I will get the top of the range UK equivalent injector cleaner and run this through the system.

If that doesn't help then I'll pop out the injectors and send them away to a specialist cleaning company.

If it is the injectors then I hope they can be rescued and don't need replacing! :-(

cheers

 

Hot side t-map ......an r53 specific part. Description sounds like what happened to mine a couple summers ago. 5 minute job, and 2 screws too fix...
Part was about $90 online for the OEM if you look around.....dealer said it was a 3-4 day item to order. I guessing the oil from the filter got on it...wrecked it....
Seafoam the intake through the PVC...this will clean the excess oil from the intake, and maybe clean the sensor..see if it helps, then change it.

 

One warning and tip...the cold side map (just a r50 t-map, the t not used, the plug has 3 not for wires) is NOT interchangeable....limits are different...
There is a BMW TIS on how to identify if it is the sensors....
I did the cold side map...then a few days later the t-map...issue went away with the t-map.

 

https://www.northamericanmotoring.co...ng-solved.html

If I remember....sometimes I would get the p0108...sometimes it would take a few days...same with the DSC...

 

Yeah. First things first. Check for engine codes. Injectors on the R53 rarely fail. That doesn't mean that yours haven't, but it's just rare. You have replaced some of the ignition parts, but after checking for codes, if you have a misfire, I would recommend pursuing the ignition angle further.

 

Almost sounds like the typical Yo-Yo problem associated with a weak spring in the Bypass Valve (BPV). To troubleshoot, you can tie-wrap the BPV closed and drive the car to see if the stumble is gone. Warning with the BPV tie-wrapped the throttle will be a little abrupt (on-off). If that solves the problem, it is time for a new OEM BPV and even better a Detroit Tuned BPV that has a stiffer spring than OEM.
http://www.detroittuned.com/detroit-tuned-bypass-valve/

 

Thanks for all the advice guys.
I'll grab a code reader from eBay and see what's being generated.
Take it from there.

Tie wrapping the BPV could also identify that as a possible cause.

Cheers