2005 Cooper S cabrio. Did a bunch of odds and ends under the hood and P1242 keeps coming up. Idles at ~1100rpm but runs fine. Looking through the posts I have read about intercooler boots, throttle body .... Have checked all those and tried the propane trick and no vacuum leaks I can detect. A friend suggested it could be the MAP sensor. Tried disconnecting it and there was no change at idle or while driving. While disconnected same codes plus P1237 and P0507 but again ran fine.

Does that implicate a bad MAP sensor???

Help

 

Come on guys - someone's got to have some input!

 

The s has 2 map/t-maps...not interchangeable....
A cold side r50 t-map next to the airbox on the driver side...but the t-funcion is not used on a r53.., and a 2nd model specific t-map screwed into the front of the intake manifold by the radiator shroud....this "hot side" t-map is a bit more critical...
The cold side one was even deleted by folks who do twin charging (SC with a turbo)....
BMW/MINI has a TIS about troubleshooting t-maps...
Frankly it sounds like a vac leak..any stray hoses?
When my hotside t-map failed, it was a stutter at midrpms and a loss of MPG...with stalling at low rpms...

 

Just a hunch...
Have you looked at the crank pulley? It rubber, and when failures happen it tends to start with one of the 3 codes you have....
Any burnt rubber smell?

 

https://www.northamericanmotoring.co...rger-swap.html

Look at this thread...another bit of info on another possible area too look at.

 

It could be a MAP sensor, but yes it could also be the crank pulley as they have caused Map faults. Check the crank pulley and do some more diag if necessary.

 

Thanks guys - I knew I could count on some good ideas. I will work on these items and then update.

 

Well, have been driving with SES light on as it ran well just a highe idle. As I sit here waiting for AAA in limp mode and code 1688 I have searched the site and should have listened to you all about the crank pulley. Consensus on 1688 appears to be the pulley. Will tow back to the house and put the ATI on when I get it. Thanks for all the advice I SHOULD have acted on.

 

Thanks for the update sound like you need to replace that pulley. Looks at the pulley while you are there and see if the hard rubber section looks deteriorated.

On the maps like they said above , there are two.

 

Pulley was completely separated - amazing it would run at all. ATI pulley now in place but P1242 still coming up (other codes now gone). Will continue to look

 

For P1242, Secondary Upstream Manifold Air Pressure Sensor Too High in Deceleration, check this NAM thread here. Linked directly to a good suggestion in that thread. Another here with some good suggestions, which ended up being the tubing for the manifold air pressure 11651504943. Hope this helps with your diagnosis. Let us know what you find.

 

Yah, I've read those and my tubing appears to be in good working order. Per another user suggestion I tried playing with the bypass valve lever pumping it in and out many times then cleared the code and was able to drive for 1/2 day without the CEL light coming on. Thinking the valve may be sticking - I have a Detroit Tuned BPV on order so when it comes I will update this post. If it doesn't work I will go back to th etubing theory.

 

Problem solved! I did replace the BPV but not necessary. Once I had the throttle body and the BPV off I had enough access to notice that the tube to the MAP sensor felt a little loose. I detached it from the plastic air intake and low and behold it was not attached to the MAP. The connector broke between the tube and the MAP.

Ordering a new tube would be 5 days and the dealer had to order one as well. Two coating of quick dry JB Weld and a good wrap with rescue tape and it is as good as new. No codes and runs great.

An aside and a different thread I have going: Every couple of days when I would start the engine, my first couple of pushes on the brake pedal would feel like there was no power assist. After a couple of pumps no issues. The MAP vacuum hose and the brake booster hose enter the plastic air intake (not sure its technical name is) within an inch of each other and I am assuming the vacuum leak from the MAP was also causing a leak at the booster.

Hope this helps someone else - and FYI, I did try the propane test for a vacuum leak but apparently was unable to get close enough to make a difference in RPM.

Cheers and I am happily driving again!

 

That is great to hear! Do you plan to replace the part or keep as is and see how it lasts? Glad things are all back together again.

 

Thanks for the update, " The connector broke between the tube and the MAP. " That stinks. Was it brittle ?