I just got my new to me 02 R53. I noticed when driving the idle hangs between shifts, I have found this to be common on many cars where the manufacturer keeps the idle high for a moment after throttle is released for emissions reasons (helps to burn off unused fuel).

Question is...on many other cars I've worked on or owned, I have performed a mod to the IAC (idle air control valve) to restrict the amount of vacuum or airflow it sees. This make the throttle much more responsive. When you lift thr throttle closes. Is there a similar mod to the R53?

I can't even see a throttle body, let alone an IAC...

 

The fly wheel is heavy I mean really heavy in this car. If you look over old posts you will find its Minis way of heel and toe with having to do it. Sprint booster may help the response because of the drive by wire throttle.

 

This isnt the flywheel, (at least the hanging) it's the ECU holding the throttle open for a little. I dont believe our cars have idle air valves, rather it is all controlled by our electronic throttle bodies. Since we are already drive by wire it's pretty trivial just to use the stepper motor that runs the TB to crack the throttle open a bit more under certain idle conditions.

The only way you are going to get rid of the hang is going into the cars brain. However you can get it to rev down faster after it stops hanging by adding lightweight components like flywheels and pulleys.


Edit: What do you mean by "the idle hang between shifts"? that doesnt really make sense.

 

When the throttle is released between shifts the revs don't come back to idle. The throttle hangs up for a second or two and then the revs come back down. This is commonly done in manual transmission cars to help lower emissions by trying to ensure that no unburnt fuel is dumped out the exhaust.

I suppose it's more of a lazy throttle response if the car is drive by wire. Maybe the Sprint Booster is the only way to go.

 

From my experience, MINIs do not keep the throttle high to burn off unused fuel. Actually, quite the opposite, to create a hi-performance feel/sound, MINIs spray a bit extra fuel when you lift, to make the exhaust burble.

 

Wow. Does your MINI shoot flames out the exhaust? Or just giant backfires? Because that's what you get when you spray fuel in a running cylinder with the throttle blade closed.

This really isn't rocket science folks. All I'm looking for is more precise throttle response. Thanks!

 

The fuel the ECU sprays on overrun doesn't make it past the manifold.

 

The 02's dont pop, but it is a feature on later cars.

Some of the lack of throttle response is the mapping of the throttle itself, some of it is the transient enrichment map, some of it is the engine winding up on its mounts.

So to answer your original question there is no IAC mod on these cars or anything similar. People have had good luck improving throttle response with the sprint booster as that addresses the TB to pedal relationship, and you can make the engine move up and down a bit faster by lowering the inertia in the engine.

The others can be addressed by remapping the ECU and adding stiffer motor mounts.

I'm curious what other cars have you done work on?

 

Oh. good thing mine is an '03 I cant live without it! And its back on the 2011's!!!! sorry for a bit off topic.

 

Honestly, I was under the impression that NONE of the pre facelift models did it. hmm...

 

Hmmm... We do have a conundrum here, Mine does it like crazy when i lift in first gear. I think it's just probably more pronounced in late models.

 

Boy, what a bunch of misinformation:

- What is being described is called Drop-Throttle Overrun, and is an emissions-reduction feature controlled by the ECU. It has nothing to do do with flywheel inertia or the gas pedal.

- On earlier cars, there was often a "dashpot" on the throttle, that made it close slowly, for the same reasons. One could disconnect the dashpot to remove the feature. No such hardware exists on any MINI.

- The Sprint Booster won't affect Drop-Throttle Overrun at all - the Only Single Thing the Sprint booster does is re-map the gas pedal sensor output to give you more gas with less angle on the pedal. Period. It won't make the engine rev up or down any faster than you can do with a little more ankle motion.

- The overrun was also annoying to me on my `05 S until I had it fixed. An ECU tune is the only way to eliminate the Drop-Throttle Overrun. My MTH tune gave me this change on request in 2006. I understand that RMW also offers this as an option with his ECU tunes.

 

I believe if you do the old vacume gain mod it will give you what you want. It s an oldey, but a goody. There are 2 basic methods and a hybird...but many folks like the change. It basicly involves re-routing a vac line...simple and easy.

 

I build hot rods and restore old cars for a living. I also do a lot of swaps and fabrication and whatnot. This is my business

www.schradersspeedandstyle.com

My last daily driver was a 530 RWHP 99 Mustang GT, it was a 2V with a custom made T70 turbo kit.

Okay, so what Old Rick wrote makes sense, thank you! But I'm interested ZippyNH...what's the vacuum line mod?

 

It's a lot easier to talk about this stuff when you know what kind of background the person you are talking with comes from. I really like your skyline-triumph hybrid.

OldRick is right on all counts, I may have been slightly off or unclear I suppose. I do all my work on sport bike motors in FSAE cars, so my knowledge pool is a bit different I suppose, we dont really have to worry about emissions.

 

https://www.northamericanmotoring.co...ystem-vgs.html

An old thread...but many folks seem to re-discover this every few years.

Many folks that have this mod may not know it....some like it, some don't just like the DT bypass valve as it changes the throttle response a bit...having both might make the the throttle hang....

 

Ok it might be off topic but, RMW can retune the throttle overun, but can he retune the backfire. In Colorado I dont get a nice burble, it is a loud and VERRY ANOYING backfire most of the time, and it bugs the **** outa me. But when I take the car to Nashville once a year it dosent backfire nearly as much, and I get more burble than BANG.

 

More transient mapping...

 

I forgot to mention the reason for having the feature in the first place.

If you were to close the throttle very suddenly, the charge already on its way into the cylinders would suddenly be unable to flow enough air in there with the fuel, and you would get a momentary rich mixture.

Unburnt fuel running through the engine is not a good thing for emissions, so they started putting this annoying feature on American cars back in the 70's, IIRC.

It's annoying because with a fast upshift, the RPMs don't drop enough to for the engine to match speeds with the next higher gear, and you get a little surge when you let the clutch out.