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R53 Mini Misfire around 4500RPM


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Running into an issue with my Mini Cooper that I can't get a handle on.

Car ran fine in the spring, then at a summer track event it started acting like it was running into a rev limiter at around 4500 rpm in 3rd and 4th gear. Had a look at my AIM data and it looked like the ECT was dropping to -40, so suspected the sensor/wiring.  Replaced the sensor and the wiring harness and went out to the track this morning and same problem, but ECT looks fine.  Replaced the MAP sensor (new)...still same issue. 

Now I suspect something in the current tune, but can't see anything obvious to me.   Have included the current tune and a log of today's issue (see late in the log).

Any help would be appreciated.  I've obviously done something stupid, but can't find it.


Mini Missfire -2021-10-23 10;10;00 am.llgx MiniOCT21-tune.pclx

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You are just kissing the MAP limit (boost cut).  It is currently set to 230kpa, you have a limit control range of 10kpa set so will start to cut at 220kpa.  You get to a max of about 223kpa in a couple of spots.  

You can raise your MAP limit another 5kpa or reduce the control range to 5kpa.  


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I thought of that just after I posted, but I thought I was fine.  Did realized it had a 10kPa control range.   I will make appropriate adjustments.  Unfortunately this was the last track day for the year and it will be a while before I get to test it out.




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  • 11 months later...

It's been a long time, but I made the adjustment to the map and put the car away last fall.

I pulled the car out in the spring and it started destroying the serpentine belt....2 ATI damper shells later I discovered that the alternator was seizing and causing the issue.

All back together and now another issue has come up...it now runs lean on acceleration (lambda 1.5).  Only changes to tune have been related to starting and idle (at least it starts well now).

I've done a file compare and don't see any obvious issue that I have created with the start/idle.  Have replaced the MAP sensor, O2 sensor, plugs/wire and coil...no change.  Map sensor is an Omni Power 2.5 bar...Could it be that I need to set the MAP limit to 245? rather than 250 (sensor limit)??

Have attached the current tune ...any insight would be much appreciated.

Log file attached in next post 


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I dont see anything obvious tune related.  Did you change the warmup enrichment table after you done that log?  In the log is has about 2% warmup enrichment still working at 80°C, but in the tune it has 20% in that cell?

Your closed loop lambda is in MAP lockout a lot, not sure if it has always been like that or if the MAP signal has gotten noisier for some reason.  Do you have an old log from before?

Does it run smooth?  Does it run like it is actually lean? - it could possibly just be reading lean due to an air leak something.  

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I did make some additional changes to warmup...still an ongoing process.

No older logs except the one in the earlier post in this thread.

I tested the intake for leaks and it all tested fine. 

It runs like it wants to go but just can't really rev up.

 Is it possible the CanLambda is messed up? New 02 sensor in it now.

Would cracked exhaust cause the symptoms?  Haven't thought of/looked into that possibility.


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  • 1 month later...

Gotcha I pulled mine off today it was super easy. Once off the car remove the bolts and gently lift it off. Bunch of o rings inside making a friction fit.  You can see them in this cutaway. You can see in the yellow.



Also is this the fellow who did the GRS FMIC on NAM. That did the Voltage clamp? 



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