Is anyone familiar with the MAP (manifold absolute pressure) sensors on the 2nd gen justa coopers? Or for that matter, what cars drive like when the map sensor is not working correctly?


Here is the problem I am dealing with: The car will on occasion shudder and be hesitant when under load at low rpm's, or at light throttle. Otherwise it runs great.


A while back I started the following thread to discuss the 08 clubman I bought: https://www.northamericanmotoring.co...se-issues.html

Ever since I replaced everything detailed in this thread, the car has run pretty well with no check engine lights on. However, when the stars are aligned just right, the car still likes to be hesitant and shudder a bit when under load at low RPM. I took the map sensor out and cleaned it with electronic cleaner, and the problem was gone for about a week. And then it returned. The MAP sensor was covered in oil, and my car sucks about a quart of oil every 1,000 miles, and I have no idea why. The entire PCV system is new, but you can see where it just sucks it through that PCV hose (it always has a large amount of oil in it).

TLDR:Could the MAP sensor cause a car to shudder/hesitate when under load/light-throttle/low-rpm? It is not consistent, so it can't be a pure mechanical failure, but it feels almost as if the air-fuel ratio is off just a bit.

 

If the sensor is giving a false reading it for sure can cause an issue.

But in my years of working on MINIs I haven't seen a bad MAP sensor on an R56 yet. So I would do more diagnosis before replacing it.

 

The thing is, I can't think of any further way of diagnosing this issue. The issue only materializes on occasion, and varies in severity. It is inconsistent with the logic of a mechanical failure, and its pattern of frequency more consistent with a faulty electronic component. It is giving no codes, and has new (and oem brand) O2 sensors, new PCV system, new plugs, and new coilpacks.

The only things not replaced that I know of relating to the air/fuel ration are the MAF and MAP. The MAF is clean and is not throwing codes, and the oil on the MAP made me pursue that avenue. The car is not terrible like it is, but somewhat irritating. This is the first MINI i have dealt with, are there known components with the R56 design known to cause this sort of moderate hesitation/shuddering when the car is at low rpm and given light throttle?

 

I installed a new MAP sensor right after starting this thread, and was going to give it some time before reporting any differences. And now I have driven it about 500 hundred miles with the new sensor installed.

So far the car seems to be doing great with a new MAP sensor, it actually seems to be running smoother across its range. With the sport button pushed, it actually seems as if that the car is doing something with the throttle responsiveness, something that was not present in the past.

This is making me think that the cause of the cars random and mild shuddering may be related to oil blow-by vapors being sucked into the intake via the PCV. Of course, there is higher vacuum in the range where my car's problems manifest, and I am wondering if the oil vapors are tampering with the MAP, which in turn causes a bad air/fuel mixture. The car uses about a quart of oil every 1000 miles, although there are no leaks anywhere. Just a lot of oil in the PCV hose.