Just bought a 2011 (definitely N18) S Auto hardtop with 45k on the clock, that has an interesting "feature" which I didn't notice during the test drive. If I'm sat at lights/stop sign, for the first 7-10 seconds, every 1-2 seconds the car very gently jerks forward. Not enough to move it with foot on brake, but enough to feel it. It's almost as if it's engaging drive from park repeatedly whilst sat there, and it stops after about 7-10 seconds. Now to make it even stranger, this doesn't happen if it's in sport mode.

I don't believe it's ever had an ATF change, but it's been serviced religiously by Mini. I have an OBD reader and there are no codes presenting as of now, no engine lights or anything like that. First stop is an ATF change I think, but even then I'm not sure if that's the cause.

Any pointers in the right direction would be really appreciated. Thanks!

 

the LCI (2011+) had this feature to disengage the transmission as long as you have your foot on the break (maintain pressure). once the ABS senses you lifting your foot, it sends a msg to TCM to engage. In sport mode, that feature is disabled because the car is now "ready" any moment for you to accelerate.

now, the on/off engagement could be because either your not applying consistent pressure on the breaks, or the fluid needs to be done. Also, keep in mind adaptation could be a factor too. perhaps the previous owner used to "rock it" at step/light signs and never do a full stop!

 

That's great insight, thank you. Clearly explains the difference with sport mode. I sit at stop signs/lights with my foot on the brake reasonably hard so it's definitely not me. I could totally believe the previous owner was rocking the car - I'm in LA so I believe this could be part of the previous owner's "california stop"!

How can I get the auto box to clear knowledge and relearn my driving? I'll do some research but just in case it's a quick answer...

Thank you!

 

some may suggest disconnecting the battery, but personally, I have software that does that. you could source ISTA/D that could relearn it.

also, jack the car and using an 6mm allen key, remove the transmission drain plug and collect some ATF to check color and smell. you dont need to drain the whole thing, just a spoon. then plug it back in.

 

Thanks. What should I be looking for smell wise?

Local mini specialist has just quoted about $650 to do a full fluid, filter and gasket change on the transmission which feels like a lot of money. Unfortunately I don't really have the space to do this myself (or the tools), despite probably being more than capable.

 

Returning to this issue once again....

So I got the ATF changed, but not a full full change. Mechanic described it as "burnt out".

The issue improved marginally for a little while I think, but it's back and the same as before.

In addition, I now have a new problem of when cold, the change from 1st to 2nd feels really quite snatchy, like the box is slamming into 2nd gear. Sitting for 5 minutes before driving off doesn't seem to help, its the auto box that needs to be cycled a bit to get rid of it.

Only done about 4000 miles since the ATF change. Is it a matter of just doing the fluid again perhaps, given it doesn't fully empty things?

 

there is a process to check the fluid level. Some people play it safe and replace the same amount that came back but that's not accurate.

https://www.newtis.info/tisv2/a/en/r...ission/4JnYJ1n