i bought my 98 mpi a year ago as soon as i got the car i needed to put new exhaust on so bought a lcb maniflow which i wish i never got but hey .I also put a k&n on the car run fine untill i drove to france on the journey it stalled a couple of times when i stoped at tolls but then started up again straight away ever since then it hase never idled right just fells lumpey put a new air flow sensor on i think if that is the green one that goes in the inlet manifold .The car also will not drive along now a low revs with out splutering any idea and if anyone has tell me which sensor is which thanks.The maniflow minifold is also a problem because it always knocks and have now had to take cat of because the manifold was making it hit the body . Thanks
Hi all.
I took a look at my Mini today (98 Paul Smith) to see if I could determine the cause of the erratic (Kangarooing) running around 1500rpm and also idle increase to 1500rpm when doing stop starts in traffic.
It had been suggested if there was an exhaust leak it could be causing the problem, but after looking at the exhaust system and finding no leaks and trying to work out how a leaking exhaust could give my issue I determined this was not my problem. I’m sure if the engine was effect by a lack of back pressure in the system then anyone fitting a free flow exhaust system would in my view have an issue but then I’m no expert.
I then decided to remove the inlet manifold and strip it down to see what I found.
On doing this I found a number of issues which was mainly corroded jointing areas around sensors possibly giving leakage issues and no o-ring present on the inlet temperature sensor and was also loose. Other than this the only other item was what seemed to be some dead play on the first part of the throttle travel until it started to move the throttle position sensor, but at the time assumed this was correct. As I have stated I’m no expert. Just an extra bit of info the engine is completely standard including the plastic throttle body which looks like a piece of C**p and will be changed for a Burlen one with a new cylinder head next year.
I cleaned all the parts up and put it back together started it up and let it warm up. Before I even took the car on the road I held the throttle around 1500 rpm and noticed the engine was still surging so assumed I still had my issues. I then assume the engine was struggling to determine the point where the engine would switch from being controlled by the idle control valve to normal throttle.
When I had a look I was positive it was to do with the slack play in the throttle position sensor. When I had a closer look and worked the throttle it was evident the return lever for the throttle position sensor located on the left hand side of the throttle body as you look at it was sticking. I got the good old WD out and gave it a spray which allowed the lever to return correctly.
So for the big test had I made any difference!
I took it for a spin and Bobs your uncle it ran significantly better than before. All I need to do know is to remove clean the throttle body assembly to ensure it won’t stick again. Ultimately the best fix will be to change it for a Burlen one.
Hope this helps.