Hi fellow Mini owners,
I’ve been combing through these forums to get a clue on my 03 Mini Cooper S JCW starting problem.
Purchased this used car for my daughter that just got her license.
This car is loaded with a lot of Mini Madness goodies like water intercooler, reduced pulley, lower springs, etc. It has about 145,000 miles.

I’m having trouble getting the car started. Here’s what happened:

1. Clutch release bearing went bad so I decided to change it and the clutch myself to save money and increase my knowledge about Minis.

2. With my Haynes manual and help from this forum, I was able to change the clutch after removing the sub frame, front bumper. While removing the air box , I unplugged the computer (ECU) next to the air filter box without first disconnecting the battery. This may/may not be related to my current problem.

3. I also dropped the throttle body during the clutch replacement. See later.

4. Well, the clutch replacement went smoothly and everything was put back together. When I started the car, the rpm was oscillating up and down like crazy and smoke was coming out from the engine, near the back where the exhaust manifold is. Found out that I didn’t connect the rubber bellow to the supercharger correctly and it was sucking in air. After fixing the rubber bellow, it ran smooth and I took the car around the block. Everything went well. Clutch nice and smooth, no strange noises.

5.. Next day I drove to Wal-Mart and when I came out, it won’t start. The engine would turn over but not fire. Had it towed on a flat bed back home, only about 5 miles. Ran the code scanner and came up with P0123 ( Throttle pedal position sensor switch A circuit high input) and P0222 (Throttle pedal position sensor switch B circuit low input). After researching the forums, I replaced the throttle body (the one I dropped) with a used one from a “05 MCS I found on eBay.

6. Installed the replacement throttle body and the it started. I was so happy . Drove to Pep Boys, about 5 miles away with no problem. But when I came out, ……it wouldn’t start again. The same thing happened, it would crank but not fire. Towed it back home again for the 2nd time in about a week. Ran the code scanner but no codes showed up. The tow truck driver suggested using the spare key.

7. The following day, after disconnecting the battery over night, I tried the spare key and it started right away. Backed it out of the garage and let it idle for about 5 minutes. Shut it off and tried the original key. It started for a minute or so and then it died. Now both keys won’t start the car. Same cranking but not firing.

8. Tried resetting the computer by pressing the odometer reset button and turning ignition key to 1, down to #19 , then to #21 and reset. Learned this from this forum.

My mechanic neighbor told me to recheck all the connectors that wee unplugged during the clutch replacement. I checked, cleaned the electrical connectors. As far as I can remember there’s an electric plug at the transmission, one for the throttle body, one for the sensor on the sub frame.

Anybody have any ideas on what’s going on ? I read in the forums that it maybe the bypass valve for the supercharger ? Could it be the ECU that I unplugged without disconnecting the battery?
Any help on where I should do next would be greatly appreciated.

 

It sounds like a start issue when warm. How about the temp sensor plug? You can also disconnect the computer and make sure all the pins are straight.

 

Thank you HRM, I'll check my Haynes to locate the wiring. Btw if anyone out there need a flywheel, let me know and all you pay is shipping. I hate to see it go to waste. I'll need to check it out make sure all the teeth are intact.
According to po it was a stage 2 or 3 Mini Madness clutch kit. It makes a clunking sound when it was installed which Mini Madness said it was normal. Maybe because it's light weight ?

I have the computer out right now and cleaned the contacts, also the wiring harness. i opened the computer to see if there are burned chip or resistor inside but everything seems clean and no burnt smell inside.

 

To follow up on my starting problem.
After disconnecting both battery cables, leaving them off overnight, cleaning the ECU contacts, double checking and cleaning all electrical connectors. The car started and I've been restarting it several times today with no problems. I haven't driven it too far as yet because I don't want to have to call the tow truck again. I drove it around the block, shut off, lock doors, let it sit for a while and restarted. So far so good.
Oh, also swapped the relay for the ECU (front one) with the fan relay (back one). They both have the same number.
Thank you for your help

 

Hope that sorted it backdoc. Keep us posted!

Thanks!