Car laggy/hesitant/lumpy driving from cold.

[jasonblake7]

Hi Guys.

My 53 plate cooper when left for a long time and you then start and pull away, until the engine has warmed up a bit it feels lumpy/hesitant/laggy. You can definately feel it as you are acceletating. As soon as its warmed up a bit its all fine. Anyone has any idea what this maybe caused by ?

Still happening after replacing the air filter, Which had never been replaced since new after 50K miles and was a bit blocked up and in a bad state. Also recently replaced spark plugs to.

[mooneymini]

I get the same on my Cooper S when its ultra cold outside.

Seeing as it's fine after a mile or 2 of driving I don't really worry about it.

But am curious as to what causes it?

[MINI-Morgan]

needs to be analysed a bit more really but more than likely one of the MAP sensors or the HT Leads. Had the T-MAP sensor go twice on mine now. First time it was really stupid temps and the second time too much pressure so the engine was running very rich when cold to the point of nearly stalling.

[R1 GNW]

Mine did much the same, when cold, lots of lag, almost fuel starvation feel. took it to the garage and it turned out to be the oxygen sensor that needed replacing. its fine and dandy now!

[RO51 BOZ]

try cleaning out the throttle body..if your airfilter has been changed for that sort of time it may be where your throttle body if clogged up.

[ringothemini]

I too am interested in this thread... My 03 MCS is doing the same..

Wouldn't the Oxygen Sensor or the T-MAP sensor result in the engine management system lamp to come on...?

I had an oxygen sensor go on my previous 06 JCWMCS twice and the lamp came on.

The MINI has 2 Lambda probes... I guess it could be either or both..

[MINI-Morgan]

T-Map will only throw a code if there is a big difference in read but in most cases not. O2 sensors will only throw an emissions light if they are reading a large enough variation at light throttle during the catalyst test. Otherwise not.... The first O2 sensor is the one thats used for your closed loop fuelling.

[adamstillwell25]

Hello,

Did anyone find a solution to the above problem. I 'm about to sell my car but im scared to because of the 'hesitant' start problem.

Thanks

[AY52]

Hi, my 02 cooper, starts ok, revs only to 4000 before hitting a dead spot, once its warm it wont rev over 1500! Cooper only has the one sensor so its arriving tomorrow, lets hope it fixes it. Also does anyone know how to get the EP warning off the clock without hooking it up to the computer?

[beken]

In Canada, this is becoming a common issue this time of year because some of the gas companies that sell 94 octane fuel have just switched to their summer formulations.

The trend I am seeing is that most of the cars that have a cold start issue (R53 cooper S) are JCW's or have custom software. They may also have reduced pulleys.

The trick is to go down to 91 or 92 octane. Fuel ignites faster with lower octane. At first people were blaming the use of ethanol, but I've been using 10% blend ethanol fuels and my car, with stock Cooper S software, is running fine.

Not sure if this is the same issue in the UK.

Cheers.