Since I got my car, I have two very minor gripes with it:

• the engine seems to vibrate a bit too much when idling, though not all the time. It doesn't seem to be an engine mount issue, because they visually look in a good state and the chassis doesn't vibrate at all.
• there is a slight delay when flooring the gas pedal. Nothing too bad, but it's not as quick as I'd like.

I also came across advice to regularly clean the throttle body, even though it's not mentioned in the service manual. And both of those issues might be caused by a dirty throttle body actually.
Before you ask, spark plugs and wires were just replaced (amazing change in fuel economy), and I chucked an injector cleaner in the gas tank not too long ago (no visible change), the air filter is clean enough (checked it on the last oil change, it wasn't even dirty enough to warrant a replacement) and the car doesn't throw any code, so there isn't really any other easy lead (and if this doesn't work, I'll just live with that, it's not important enough to really matter).

I was planning to take the throttle body out and clean it this week-end, but after watching ModMini video and checking other videos, I wonder if it's a good idea or if I need more preparations: ModMini talks about throttle body adaptation when replacing, and apparently if you even move the flap a little, you might need to do it. Problem is, my cheapo OBD2 scanner doesn't have this option ...

• I saw in ModMini comments and on another video for BMWs that you can do the adaptation by putting the car in KLR (without starting the engine), flooring the gas pedal for 30 sec, removing the key and waiting a few minutes before restarting the car. Did anyone test that on a first gen? First question because that's what I'm the most worried about: messing up the adaptation and not being able to have the car re-learn it, leaving it in limp mode.
• Do you actually need to remove the throttle body to clean it? Advice seems to be conflicted here, there are several sources that says to remove it, and others that say it's not necessary.
• PelicanParts tutorial on throttle body cleaning advise to replace the gasket between throttle body and intake manifold everytime it's taken out, is that really necessary? If it is, I might try first to clean the throttle body without removing it...
• if removing the throttle body, what's the torque spec for the bolts on re-assembly? ModMini doesn't torque it and just send it with an impact, but I'd rather torque it properly if there is a spec. Either I missed it or my manual don't have that torque spec.

Obviously, any other advice on the operation or other cause for the issues I mentioned is welcomed.

 

The only time in hundreds of thousands of miles of driving I actually needed to clean a throttle body was when an air/oil separator had failed and an excessive amount of oil vapor was making it through the AOS into the intake. It was so bad that the TB was fouled with oil. A drop of oil was hanging from the bottom of the butterfly valve.

But that was the only time.

If you find the TB dirty enough to clean there's probably something else wrong.

Oh, I did remove the TB to clean it. After removing it I sprayed it down with a can of aerosol cleaner that leaves no residue. Brake cleaner or maybe I bought a can of electronic or even MAF/Throttle body cleaner. I can't recall now. But it must not leave a residue.

I can't recall for sure now but I believe the TB I removed/cleaned was sealed with an o-ring. I do remember I didn't buy a new o-ring (or gasket).

But I was prepared for a leak. None happened.

If the TB uses a gasket I'd get a new one. If you are going to remove the TB and clean it you want to be sure you don't cause a problem so I'd recommend you use new gasket.

Handle the TB with care. If you drop it you ruin it. Do not move the butterfly valve. Just spray the dirty areas of the TB with cleaner and let the dirty cleaner run off and be sure the gasket surfaces are clean and dry and fit the new gasket and tighten TB bolts down. I had a torque wrench. You don't want the thing loose but you don't want it tight and you especially don't want it tightened unevenly.

For my car there was pedal/TB calibration I could perform from behind the steering wheel. If there is one for your car you obviously need to know what it is and do it. I stress you must know for sure what (if any) calibration procedure there is.

In fact for my cars with a pedal/TB calibration procedure the techs advised it be done every so often. Only took a minute. I did one every couple of thousand miles.

 

For reinstall:
Replace the seal on the base of the throttle body (part
number 13547509045)
When refastening the throttle body bolts be sure to
refasten the bracket secured to two of the bolts.
Torque:
Throttle body bolts 7ft lbs 9.5Nm

It wouldnt hurt to clean, mine was pretty filthy when removed.

Also check your vacuum lines

 

Thanks for the input!
I guess first step is a visual inspection of how dirty it is. I might try first a quick TB cleaner spray without removing it nor touching the butterfly valve to see if it changes anything.

I looked up the gasket part number, it's 13547509044 for non-S models. I assume the torque spec is the same for non-S and S models, but 7ft lb / 9.5Nm seems super low. My torque wrench starts at 14Nm.
I'll get that ordered before I think about removing the TB. If not needed it will join the rest of the "just-in-case" parts.

Well, I don't know it, that's why I ask.

Will do, thanks for the suggestion!

 

https://x8r.co.uk/over/mini/BMW-Mini...tion-guide.pdf

page 23

 

I asked that over the PelicanParts page dedicated to throttle body cleaning/replacement and received an unequivocal answer: that procedure will not work on a first gen Mini. A scan tool is needed. So step 1 is to get a scan tool that can do that.

With all that said, my issue isn't important to justify spending somewhere between 200€ and 500€ to get an advanced scan tool able to do that, so that's going to the backburner of things to do "eventually" (and before someone suggests that, no, borrowing is not an option, parts store in my country don't do that, and none of my friends have that).