38 replies to this topic

[xrocketengineer]

It might be a long shot but it seems familiar. When I bought my 94 Cooper, the idle speed was like 1200-1300rpm. I found that the elbow at the back of the manifold for the red vaccum line for the Thermac valve was cracked. When I replaced it the idle speed went down to 900- 850rpm but only while the engine was not fully warmed up. Then it would die at idle and in betwen gear shifts but drove fine. So, I went back behind the manifold and found that the non original vacuum hose going to the fuel trap had partially dissolved right at the port into something like chewing gum and had collapsed. This was creating an obstruction and the MAP sensor was sensing a poor vacuum signal from the manifold. I replaced that piece of hose and after it worked fine. I would check the lines for obstructions and the fuel trap for leaks.

Ivan

[Racing Gold]

Hi, Yes that was confirmed by one of the auto electricians who looked at it and actually had the equipment to test it and the cable is set correctly

[icklemini]

well if the idle and lost motion is set correctly...

ignition been isolated from the ecu by running a distributor... so kinda rules that side of things out..

would suggest its going lean when the throttle is being closed.... air leak???

personally though I would confirm the idle setting on the stepper...

[Racing Gold]

The whole inlet manifold with sensors has been replaced and the vacuum pipes which are the correct 'Rover' ones. The unit has been tried on another car and it works fine. No air leaks

[Racing Gold]

Me again and yes to the above. Shortly after the above, the car went to the Rover autoelectrician mentioned above. I got the car back last week after 4 months, of working on it in his spare time whilst working at an ex rover garage. He has been unable to fix it! Still does the same. He thought he had resolved it on one occasion when he set up the stepper with all his gear, but after a driving it for 10 mins, it reverted to cutting out when revved from idle. So the update is--still stumped! Will probably be scrapped which is a shame as it has only done 29000 miles

[icklemini]

whats the live data when it dies? - I have a hunch its gonna be something *really* silly - like an air leak or such like...

[CarsOrBikes]

isn't this the model with the throttle switch above the pedal that plays up?

[Racing Gold]

No they stopped fitting those in 92 and the cars had the twin plug ECUs which also ceased.

[Racing Gold]

An update, yes over 2 years I know . Short answer, I kept banging on about possible earth problem to all the autoelectricians i paid to look at it without result. After fitting 4 extra earths, engine lower steady to inner wing, clutch 'wok' to bulkhead above pressure valve, thermostat bolt to bulkhead by radiator and another battery earth to boot floor car Runs without fault!! Took it for MOT yesterday and the emissions never been so good.

[dbcool20]

Yes indeed it's been a while. had been reading this thread quite at the beginning. Its nice to hear you finally got things sorted and the mini is running fine now. Quite strange though that all the auto electricians you visited were not able to find the problem. And even stranger is can't really figure out why it would only die when letting off the throttle if it's a ground issue? 

[Racing Gold]

It seemed to me that all the time the car was 'on choke' so to speak, a richer mixture , fine, revs overcoming a possible earth problem. Once it warmed up and the revs dropped to around 850 all was fine. It would sit on the lean mixture of warmed up engine at 850 all day. As soon as you revved it and took your foot off, replicating stopping at a jumction, it dropped down in revs and died . It was as if the initial richer mixture was keeping it from stalling but once up to temp------and leaned off---!- It is off to IMM next week and joining a group of us in Classics who are touring the First World War sites in Belgium and France at the end of August. I have total confidence the earths have cured it! (Fingers crossed)

[dbcool20]

Yes i quite understood what your problem was, but what i don't really get is how the ground affects this, and why only when letting off the throttle and not an other time?  Could it somehow be due to the engine movement when letting off the throttle which was giving a bad ground for some reason? Well Have a great trip then, sound nice! And hope all will go well 

[Racing Gold]

Thanks for that.

[Racing Gold]

An Spi I took for MOT last July, 2013,struggled to pass the emissions test despite having full service, new cat and bosch Lambda with htdrocarbons at 196 and CO 0.25. This year with a further 6000 miles on the clock, I decided to add the extra earths as per the above and take it for MOT. It passed with CO at 0.07 and hydrocarbons at 23.!!! Read into this what you will !!!

[Racing Gold]

An update for those who have running issues, the car remains sweet with its extra earth leads and has sailed through its MOT's eversince. Each year a group of us in Minis tour the Battlefields, including this car and it runs without fault. I found an article by Keith Calver in an old Minimag where he spoke with one of the men who designed the MEMS for Minis. He pointed out that these vehicles with electronics were getting old now and 'crud ' uilding up on electrical connections would cause problems with components. Earths being the key to overcoming the problem, something I found. Problem is these Spi's have had their wiring pulled about,cut into, unclipped and not secured and we wonder why we have problems. The classic being the battery running flat and people buying new ones and new alternators when the problem is with an internal break in the wire to the starter solenoid/starter motor caused by it not being cable tied to the solenoid as from factory, to stop it waggling about. Anyway back to the garage!!