Running as lumpy as SHI.........
Hi,
Speaking on previous experience with the Rover MEMS injection system ECUs (which, if I rightly recall, the SPi/MPi Mini has), there could be 2 points of failure worth checking.
Firstly, ignition timing is controlled by a knock sensor, which detects pinking, and adjusts the timing accordingly, have been known to fail. Ive come across this on Rover 820 models before... a way to test it, is to find it, and pull the multiplug off... on a good engine, the tickover will be lumpy as hell, and on revving, will exhibit the same characteristics as your machine.... as it cannot detect pinking, so it will go into failsafe mode, and retard the timing fully, to prevent engine damage.
Secondly, another common failure, is the Intake Air Temperature Sensor, and this can be found on the inlet manifold or in some cases, the air filter housing or trunking... on the K series engined Rovers, this normally has a Green coloured plug, and the part of the sensor that the plug clicks onto is also green. Its worth taking this out, and giving it a clean, to ensure that it hasnt been covered with oil, and giving a false reading. Basically all these are, is a Thermistor (a head dependant resistor), and can break down and fail. Again, if the ECU detects an open circuit or a vastly different value from what it is pre programmed to read, then it will shut the engine down into failsafe mode.
The final check, is the little plastic vac tube that will run from the throttlebody or manifold, to the ECU. This is for the MAP (Manifold Absolute Pressure) sensor, and this is quite a critical device in the MEMS system. Make sure that there are no leaks (ie that it isnt sucking air in), and pull it off, and blow through it, to make sure it hasnt been blocked by oil/gunk. A good way of checking for vac leaks, is to get a length of rubber fuel hose, stick one end in your ear, and use the other end to sniff round your manifold, in kind of like a stethoscope manner!
Your Mini may or may not have all the things that I have listed above, as I have never worked on an injected Mini, but I know that my 95 Sprite had a MEMS ECU... but I have had plenty of experience over the years with MEMS equipped 200/400/800 series Rovers!
Hope this offers some advice!
James
Posted: Oct 11, 2006 03:45 PM