I just bought an '03 MCS from its original owner with 75k miles (if you look at the classifieds here, you'll be able to find the car ).

I've got a couple things to track down with it, the first being the cause of code P1688, which looks like hte supercharger bypass valve. First, the symptoms: Car runs fine, but upper-RPM range, under load, there's a good chance that the car will go straight into limp mode and throw the code. Restarting the car clears up the problem and the SES light goes off after a few key cycles.

From a bit of digging, it looks like the supercharger bypass valve. I'll go with the uprated on from Detroit Tuned, since I'll be doing a 15% pulley soon, as well.

What should I look for in the replacement as far as performance difference? I'm assuming it'll wake up the upper-RPM range, since it seems to really weak up there.

What about the actual replacement? I'm reasonably adept at this stuff, so I'm no worried, but I haven't dug into a Mini yet... how big of a job is the replacement?

 

Getting it apart is the easy part, but it's much easier getting it back together if you remove the factory studs on the end of the intake manifold and replace them with bolts. You'll know what i'm talking about when you get in there.

 

Wish I'd known that before my BPV replacement. Detroit sends great instructions with their part. Well worth heeding.

Paul

 

Oh, I've got all the parts ordered. Detroit Tuned modified bypass valve (that should take care of the immediate problem) and 15% pulley, belt and a set of plugs (that should provide a bit of fun on top).

The installation looks pretty straightforward, but I haven't seen much about the tensioner tool -- is the separate tool required, or can I do it with something more common that may already be in my toolbox?

 

You can do it with really long screwdriver or a breaker bar, but it's way easier and safer to do it with the specific tool designed for it. I've done it both ways and the actual tensioner tool is by far the better way to go, IMO.

 

Thanks for that... this time, I'm going to try it with a long (20"+) screwdriver. Does anyone have a pic showing the serpentine belt layout and where the pivot point is for the tensioner? I haven't gotten a good look at it yet.

 

I'm assuming you are talking about the pulley?

 

Yes, I'm going to be replacing the bypass valve to correct the current problem (limp mode over 5k rpm and lack of boost, with P1866 as a code). While I'm in there, I'm going to do the 15% pulley and belt replacement.

 

Cool, have you replaced your BPV yet? I going to replacing mine soon and would like to know how hard or easy it was for you, thanks.

 

Just ordered it from Detroit Tuned yesterday. I'm relatively nearby, so I should have the parts by tomorrow. Operation should start on Thursday.

 

Cool, keep us posted, thanks.

 

Do a search in the MINI mods forum; IIRC there's a good writeup of the whole process there. The pivot's very obvious once you get your head in there.

Do watch your fingers. The tensioner's pretty stout and if you're not going to use the proper tool for releasing the tension it's real easy for it to slip while you're unloading the belt. Very, very easy to squash a finger to pulp, or for that matter to seriously damage the idler or the crank pulley.

 

Correct tool is cheap investment compared to possible problems. Especially if you change the belt 2-3 times a year. Real easy to do with the right tool.

 

Well, the replacement of the valve isn't too bad. Unfortunately, there is a terrible bit of design in that area -- the supercharger inlet pipe.

See, on one side the throttle body and the supercharger bypass valve connect to the plastic supercharger inlet pipe. The other end is underneath the intake manifold (which is underneath the intercooler). However, the pipe is secured to the supercharger by one bolt through ONE PLASTIC TAB. The slightest bit of extra force in getting the bypass valve disconnected will greet you with a plastic *snap* of that sole tab breaking and then you'll have more work. There's nothing to do but replace it, since the car will not idle with the inlet pipe unsecured, since it will let unmetered air in.

The inlet pipe is $110+ form the dealer and to replace it you have to pull the front of the car off... bumper cover, reinforcement, enough of the radiator mount to pull the radiator away. For my first experience with BMW/Mini design, I'm not impressed.

Oh, by the way, my original bypass valve was definitely dead, the acutator arm just rattled back and forth, so it was not letting the car build boost at all. Hopefully when the part comes in tomorrow it'll run better to the point that I'm not mad at it anymore.

 

Update: I got the replacement inlet pipe and new gasket on Friday. In 20 years of working on cars, I've never seen an element of design so poor as the mounting of that supercharger inlet pipe... and I've worked on hundreds of cars doing all kinds of stuff to them. 1 part of a plastic tab breaks and your car is dead in the water until the front of the car is removed a plastic tube buried in the motor is replaced. Not pretty.

That said, the installation is reverse of removal, once you've taken off the bumper cover, reinforcement and enough of the header panel mount so that you can pull the radiator forward.

The car is transformed. Much more power available everywhere and smoother, as well. Not surprising, since the stock valve was fully shot and the car was seeing minimal boost.

Now off to track down the other niggling problems.

 

Thanks for the update. I'm thinking i'll have my mechanic install the BPV.

 

Don't forget to replace the bypass valve o-ring. These leak over time.
As for the front end coming off, I love it. If you know how it assembled it is removed/installed very fast and easy and it opens everything up. One of the easiest front ends I've worked on. I think it is a great design.