Hello,

I have a 2006 Cooper S that is having some issues as of late. The biggest issue that I have found is with the idle and light backfiring. I know backfiring on deceleration is normal, but this is occurring with light revs below 3K. With very audible popping sounds and vibrations felt in the cabin.
Also, not sure if it is related, but if I just ap the gas really fast, the response time is very slow and some times doesn't even react. I can hear a sucking in sound around the air box whe. Doing this, but I can't seem to find any air leaks around it. A few weeks ago, I reset the ecu using the computer and it changed slightly for a day or so, but reverted back afterwards. Also, when tapping the throttle lightly, the revs will hesitate going up and when returning to idle will drop too low causing a near stall situation at times. This drop in revs is not all the time, probably 5 out of 10 light revs would have this occur.
If anyone has any suggestions or advice, I would appreciate it very much! Really trying to get ready for winter!
Thanks in advance!

 

When did you last change the plugs? Wires? clean the injectors? I would do these cheap things first and see how it runs, I have a cold air intake and also have that noise but no back firing.

 

Sorry, I left that out! I recently had a tuneup performed (new plugs/wires). I occasionally run injector cleaner when I put gas in it, but haven't in a while. I'm really not sure what could be causing this, and everything is stock right now! Just afraidthat it's something more! :-(

 

Perhaps it could be a bad throttle body or idler pulley. I have recently had to change both on my car and it made a huge difference.

 

Well I hope not, but I just put an order in for a new upper engine mount and bushings for the lower and gearbox. I have my fingers crossed that this fixes a lot of the issues, but I am very open to suggestions! Thanks!

 

Any advice on how to check if those items should be replaced?

 

Reving anywhere between 2-3k will definitely cause backfire/popping. As for the slow throttle reaction, it's probably just the drive-by wire doing its job. A delayed reaction between pressing the pedal down and the throttle actually opening is normal for our cars.

 

That makes me feel a little better! Hopefully the mounts will fix the shaking and difficulty to shift! We'll see. I'll keep this thread updated when I get the parts installed.

 

You might be referring to the different ways the "burble" occurs (as some like to call it), which is built in for '05 and '06 R53s. If you are driving at a constant speed and let off the throttle, you will get a mild popping sound. If you go WOT and then take your foot off the accelerator, you will get a more defined cracking/popping sound. The ECU is trimming the fuel and does so in different ways in response to your acceleration methods. The MINI engineers thought this would give MINIs are sportier sound from the factory.

Add to this any aftermarket exhaust, like my Invidia setup, and the backfire sounds are enhanced even more. As for the intake making the "sucking" sound, any aftermarket open air filter will have a more defined sound compared to the stock air filter box.

Interesting on the near-stall issue. One thing that comes to mind is some of the ECU updates reprogram the idle circuit to the point it's trimming the fuel too much (hence the infamous "idle wub wub wub" sound, as some like to call it). This is, unfortunately, irreversible, unless you find a MINI tech that will go backwards on your ECU update. Also, retuning the ECU with an aftermarket setup modifies the main and WOT fuel circuits, not the idle circuit. Check to make sure your air filter is not dirty to the point it's choking the engine.

As mentioned above, make sure your wires and plugs are seated properly. Check the terminals on the coil pack. #3 terminal is known to corrode real easy. You can clean them up using a brass brush or a rag with some carb spray cleaner sprayed onto it.

If you don't get any SES light codes, you should be good. Happy motoring!

 

Check for air leaks to as that will make the computer have readings that are not accurate.

 

Thanks for your posts! The backfiring I am concerned with is only at idle, the other I actually like . The car is completely stock at this point, would the stock air box still have a sucking sound with a tap of the gas? I tried looking for vacuum leaks, but I am not sure where to look as everything seems to be under the airbox? Hopefully that's all this is!
I haven't had the ECU retuned at all, but was considering an aftermarket solution. Most likely not anymore since idle won't be affected. Thanks guys for the replies!

 

Quick update:

I had the TSW engine mount installed as well as bushings for the lower mount and gearbox mount. The problemm is still there! Although it does ride smoother in higher RPMs. Low-Mid RPMs have a lot of vibration from the TSW mount. Is there anything to do to reduce the in cabin vibrations? I think it's as good as it will get right now as far as being broken in. I have an annoying exhaust vibration to deal with now though!

I recently found that when the car idles, if I attempt to raise the RPMs to say 2000..it will hit 2K than taper back down to idle, and this will contine until I let off the accelerator (constant bouncing from idle to where ever I set the pedal, below 3K). When I push the accelerator to move from a stop, first the idle drops slightly then picks up and increases. Any ideas what may be the culprit?! I am leaning towards BPV, but I am unsure how to check it for problems. I am still getting a "yo-yo" feeling even after the bushing install, so that's why I am leaning towards BPV and most likely belt as well.

Does anyone know steps to cleaning the MAP sensor? I have read in a few threads that after cleaning the problems were reduced. Kind of curious if this would help, even temporarily is alright with me!
Thanks in advance!

 

The TSW mount will provide more vibration because it's a solid piece of polyurethene. The outside temperature will also affect it, especially below 40 degrees F. However, once the engine compartment has warmed up, it will go down some. Also will get better as Spring and Summer approach. But that mount will never go bad on you again.

As for the idle/RPM issues, it is possible the BPV is the problem. The Detroit Tuned BPV is a great stock replacement. You will have to slightly adjust your driving habits, and you will lose 1-2 MPG depending on your driving habits. The spring is stiffer and causes the valve to slam shut fairly quickly.