2003 S has issue with iddling. Start up fine. RPM around 1000.when it's warm and up the car idles at around 1600 and slowly goes to 2000 then drops back down to 1600 then repeat's this cycle constantly.
My story, bought 2002 base but it has installed 2003 S. I tried to save the car because the owner gave up with overheating issue. I replace water pump, thermo, refresh supercharge, trans oil, new spark plug, new radiator, new radiator fan, serpentine belt, new oid, new ps pump and fan, new KN air filter, new cv boost, axxle bearing, relocate the battery to the trunk, and try to put it back to life.The car is abused.. Need your help.
AL

 

2 things:
It sounds like a simple vacuum leak somewhere - what color are the spark plugs - whitish?
Reset the fly-by-wire throttle - ignition on, engine off - floor the throttle pedal & hold it a good 30 seconds.

 

The Spark Plug is white as it is newly install. No discoloration. White...
How do I check for the vacuum leak? Thank for the help.

 

MINIs tend to run rich so the plugs are generally clean after a decent run but on the sooty side.
With the engine running, gently spray around the vacuum lines & connectors. manifold joints etc - use water, brake cleaner, pretty much anything.
If the engine speed changes, up or down, you've found the vacuum leak.

 

Second question. I noticed today while to try to find the leak, the exhaust is red hot while the RPM ran up and down. The temperature gauge indicated in the middle.
I was so worry then I turned the engine off. The exhaust and the connector below it showed like the metal run high heat to the melted point. What should I look for? is that normal on the mini?

 

I think the engine must have been idling for quite a while to generate that kind of heat. I believe it's also a sign of a failing or blocked catalytic converter. Is this a car that's only been used for short runs?
The temp gauge on the MINI is pretty vague. There's a secret menu that shows a somewhat more accurate temp of the engine coolant - lots of threads on here about how to display it. It has little or nothing to do with exhaust temperature. Did you find any vacuum leaks? A weak mixture will increase both engine & exhaust temperatures. Mid or top-grade gas is essential for the R53.

 

Yes, It ran for about 10 minutes. And thank you for your support. The car still on the stand. I did not know how long the car has been parked. Base on the seller he said the car had parked for more than 6 months. I drove less than a mile then noticed the overheat. Towed it home then put it on the stand since. I work on its when I can. Did not notice the RPM because it on the road. First issue I tackled is the overheat: problem was the original radiator base model was modified to fit S engine and leaked. Radiator support was modify to give room to Supercharge. Radiator fan is broken in the previous process. More problem found as water pump leak, thermal stat leak, serpentine belt is aged, worn/brown tip spark plugs, figured the supercharge did not taken care. PS pump failed as leak and not working, it was no power when turn the wheel, technically this car had been beaten very bad. I try my best to work on it. So far I was followed most of the instruction to replace the failure parts on this car. I was happy when it turn over and the overheat has been taken care. In the process I found more issue. I am trying my best to fix this car.

 

The red hot headers are usually caused by a clogged cat BUT could be getting hot from it running so lean and it would be running lean from a vacuum leak.
and not trying to throw shade but you bought a car that isn't running well and ontop of that it's a swap that you didnt do. It appears that you dont have experience with these and these cars even stock , can be a headache sometimes to track down issues... in all honesty , I would run from that car. It already looks like it's taking alot of money and time... I would highly suggest thinking twice about going into it more.. unless it's a car you just absolutely gotta have which I dont blame you as I've been there ( 94 tbird supercoupe )

 

Thank you all. I will try to isolate the vacuum leak issue.

 

Google smoke test on a r53 , I found a how to video where to inject the smoke and used a cigar and cheap handheld fluid transfer pump to push in the smoke . Was cheap n easy .

 

Thank MinimanAdam I will figure it out this weekend.
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The cherry red exhaust can be from a leak letting air in where it shouldn't. I had that when one of my intercooler boot was cracked, it was idling badly and the exhaust would turn red from simply sitting there. When there's air coming in the system that's not seen by the sensors, it makes the engine run lean and lean means heat.

I'd check the intercooler boots and pretty much everything else that's connected to the intake side.

 

This is how I smoke tested mine , I used a cigar and a 5$ hand held fluid transfer pump from harbor freight but any auto parts store sells them.put the lit cig in one end and the other tube into your vacuum system through that port In the video and pump it full of smoke and look for leaks ..

 

I did smoke test using similar method (Jar/Cigar/Hoses/air pump). Thank you for the recommendation, and I did not find any leak. Thank for all the information specially the car ran lean pointer. I retraced every steps to learn where did I made mistake. The supercharge valve is the cause. I did not inspect nor remove it at the first round. The valve stuck when engine warm up. I took the front/radiator/valve cover/suppercharge out again to inspect, found the Starter cable melted due to the high heat from catalyst converter area, found out the heat shield did not put back in when the previous owner swapped the engine/transmission, fix the cable (give it a heat sleeve), put two heat shields back on, and remove the bad valve off. New valve arrived and put everything back in today. The car start and ran OK. No more high RPM at idling. No more red hot catalyst converter. I let it idling for a long period of time. You guys awesome... Next will be the test drive, may be next week.