erratic idle on start
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Describe rough? I know when cold my previous Cooper D used to idle at about 1200rpm to warm up, then after a short period maybe pushing two minutes it would settle down.
Thanks for all your replies. The erratic idle happens roughly 6 out of 10 times. Like Keni it sometimes cuts out when reversing. Got my dealer to check it when I took the car for its 1st service but the diagnostic failed to reveal any fault. Had the high pressure pump cover replaced as per enhancement - I wonder if this is cause of the problem. I will let you know if the issue has improved,
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I hate to say it but it looks like it is by design - retarded ignition for the first several seconds until the CATs light off... Here is a quote from an article on Edmunds.com (link follows):
"There are other times when the Mini's is uncharacteristically coarse. It happened when I fired it up first thing in the morning and got underway, and at the first traffic signal 100 yards away as it rolled to halt. That's when I noticed it. It was a thrumminess that I'd not observed previously.
A few seconds later, like a switch, the coarseness stopped. Just like that, it was back to its usual unusually-smooth (for a 3-cyl) self. All while I waited at the red light.
So, what's going on here? First off, it's completely normal. During a cold start modern engines run very retarded ignition timing in order to introduce additional heat into the exhaust stream. More specifically, to help light off the catalyst, which needs to cross a certain threshold temperature before it functions in earnest.
This highly retarded ignition timing results in increased combustion instability during idling conditions. In other words, each combustion chamber's "burn" wants to do its own thing, relatively speaking. There's a wider variation in output among all cylinders, and also a wider variation in each cylinder's output from one burn to the next.
This combustion instability manifests itself to the vehicle's occupants as rougher operation.
Once the engine controller is satisfied that the catalyst is lit off (a decision that involves the input of air temperature sensors, the oxygen sensor, coolant temperature sensor and more), it switches the ignition timing out of cold start mode and reverts to a less-retarded ignition calibration. It's a switchover you notice in the Mini, more so than in some other cars."
https://www.edmunds.com/mini/cooper...014-mini-cooper-temporarily-rough-engine.html
"There are other times when the Mini's is uncharacteristically coarse. It happened when I fired it up first thing in the morning and got underway, and at the first traffic signal 100 yards away as it rolled to halt. That's when I noticed it. It was a thrumminess that I'd not observed previously.
A few seconds later, like a switch, the coarseness stopped. Just like that, it was back to its usual unusually-smooth (for a 3-cyl) self. All while I waited at the red light.
So, what's going on here? First off, it's completely normal. During a cold start modern engines run very retarded ignition timing in order to introduce additional heat into the exhaust stream. More specifically, to help light off the catalyst, which needs to cross a certain threshold temperature before it functions in earnest.
This highly retarded ignition timing results in increased combustion instability during idling conditions. In other words, each combustion chamber's "burn" wants to do its own thing, relatively speaking. There's a wider variation in output among all cylinders, and also a wider variation in each cylinder's output from one burn to the next.
This combustion instability manifests itself to the vehicle's occupants as rougher operation.
Once the engine controller is satisfied that the catalyst is lit off (a decision that involves the input of air temperature sensors, the oxygen sensor, coolant temperature sensor and more), it switches the ignition timing out of cold start mode and reverts to a less-retarded ignition calibration. It's a switchover you notice in the Mini, more so than in some other cars."
https://www.edmunds.com/mini/cooper...014-mini-cooper-temporarily-rough-engine.html
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hag6, just curious if your HP pump cover replacement had any effect. I was at the dealer today to get a new battery installed and the service advisor (who to me looked to be about 15 years old) said that the rough idle should not be there, which brings into question the validity of the article I posted earlier.
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Update to my issue. Recently received the classic P1033 Upstream O2 Sensor slow response Check Engine Light. It then dawned on me that a worn out O2 sensor may be why I have been seeing progressively worse stalling on cold start for the past three years. I replaced the sensor and must admit the car is doing MUCH better - I have purposely tried taking off right after engine start to serif I had solved the problem altogether and have been successful about 50% of the time, so not completely gone but then again I am not sure I was ever taking off that quickly in the first place. All said and done, I am seeing much better throttle response and pep from the car. My mileage at time of sensor change was 100,832.
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So it's been a little while, and the CEL P0133 came back, even though I had just changed the O2 Sensor. Other possible causes are vacuum leak and dirty MAF. I cleaned the MAF and it had no effect. Still rough idle on start. I can't find any vacuum leaks. Not sure I have any option but to leave it with the shop to diagnose next morning. 
I am new to Mini ownership, I bought a brand new Cooper in December 2019. My experience may or may not have a bearing on this issue. I have noticed that with a warm engine, if you switch the climate control off when the engine is at idle the engine becomes uneven and lumpy. Switch the climate control on again and the engine smoothes out even though the engine speed stays about the same. Is this normal I wonder?
In general use the engine is beautifully smooth as long as you keep it above 1500 rpm if its under load and you ignore those gear change indicators that seem to want you to change up far too early.
In general use the engine is beautifully smooth as long as you keep it above 1500 rpm if its under load and you ignore those gear change indicators that seem to want you to change up far too early.
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Erratic Idle was the funniest Python
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