8 replies to this topic

[QuintonNeaves]

Hi, 

 

I don't know much about Mini's as I am a fairly new owner. I don't know anything about mechanics in fact.

 

My 1993 Rover Mini Spi will crank around 5/6 times before the engine started when cold, once it starts, it will idle at about 200 revs and then gradually pick up over 5/10 minutes as the engine warms up.

 

Any ideas what this could be? There are a few forums on idling problems but nothing that matches this problem (nothing I could find).

 

Any help is much appreciated

[minimat]

I had this once,turned out to be the stepper motor at fault,see if the linkage moves much on the side of the throttle body you should see the plunger move out and push against it,could also be the coolant temp sensor.

[QuintonNeaves]

I had this once,turned out to be the stepper motor at fault,see if the linkage moves much on the side of the throttle body you should see the plunger move out and push against it,could also be the coolant temp sensor.

Thanks :) I took it to a garage about a week ago as it would either not idle at all or would idle at about 2500 revs, he cleaned the stepper motor up as it was sticking, might have to try the coolant temp sensor and see what happens.

 

Which one do I need and are they east to fit?

 

Inlet Manifold Coolant Temperature Transmitter - SPi - 1992-96 Thermostat Temperature Transmitter - SPi - 1992-96

Edited by QuintonNeaves, 06 August 2015 - 02:50 PM.

[minimat]

Inlet manifold coolant temp sensor is the one,easy to fit but hidden under the inlet manifold so you will have to remove it to get at it,i would try and get a genuine one if possible,stepper motor is also easy to swap but not sure about avalibilty or price but they are shared with a loth of other rovers of this era eg metro/100,200,400 etc,in the days when you could wander round yards i got several as spares for next to nothing.

With the stepper removed but still plugged in i turned the ignition on but not to start and could clearly see the gear was not moving as much as the replacement,once fitted it was spot on.

[humph]

I'm guessing this is a continuation of your original thread here

 

http://www.theminifo...e-from-exhaust/

 

Ok some questions before you start replacing parts. When was the car last serviced? When were things like plugs, rotor arm, HT leads changed last? Is the car overfuelling? Is there blackening of the spark plugs & exhaust pipe? Is there backfiring?  Check the easy stuff before changing the stuff that's hard to get to, do you know anyone with (& knows how to use) a code reader? What about a vault meter?

 

I had a similar problem to this and the code reader diagnosed a faulty O2 sensor in the manifold. A new one had already been fitted so this seemed strange. Looking into it further with we found that there seemed to be a break in the wire to the O2 sensor heater (as well as plenty of others) giving the intermittent fault. This is a common thing as the engine bay loom rubs against the bulkhead and manifold. I had mine repaired by an auto electrician.

 

See my thread thread here where the problem sounds very similar, especially see my posts 5/9/2010 & 21/5/2011.

 

http://www.minifinit...22&t=86339#wrap

[spiguy]

As above, don't just start throwing parts at it. It gets expensive quickly, and may still not solve your issue. If the car is running fine when warm, then there is every chance it will be stepper motor related. Just so you understand what it does, basically it is your idle control - or at least part of it. It is a motor which is controlled by the ECU. It isn't a spinning motor, it is a stepper motor, which means that it can move in increments. As the motor and it's gearing are attached to a lever which acts on the throttle, it can effectively 'push' the throttle, in much the same way that you do with your foot on the pedal. The stepper motor is used by the ECU along with ignition timing to alter the idle speed of the engine. At cold start, the stepper is used more than when warm, to raise the idle speed during warm up. Once the car is warm, it is typically used to compensate for a drop in engine revs at idle due to electrical loading, such as headlights, demister etc, which put more load on the alternator resulting in a drag which lowers the idle speed.

 

Stepper motors on minis are known to give issues, mainly due to failure of solder joints on the circuit board inside, or sometimes failure of one or more of the coils of the motor itself. The first thing would be to establish if the stepper is working at all. One easy way to tell is that when you have the engine running then switch off the engine, the stepper motor will index so that it is in a good position for the next start.  You will be able to hear it doing this, it makes a clicking sound for a couple of seconds. Post back once you have checked this and we will be in a better position to advise.

 

As for the number of cranks before the car starts cold, I would say that is OK. My 92 cooper SPi also takes about 6 compressions (this will be what you mean) before starting. I initially thought that was odd, as I am sure my last car a 95 cooper SPi started quicker, however I discovered through experimenting that the time taken is due to the time it takes fuel to get into the inlet manifold. It's always the same number of compressions, has never changed so I am not worried about it and would suggest that you shouldn't be either. I find that a hot start is quicker - maybe 2 - 3 compressions.

[QuintonNeaves]

I'm guessing this is a continuation of your original thread here

 

http://www.theminifo...e-from-exhaust/

 

Ok some questions before you start replacing parts. When was the car last serviced? When were things like plugs, rotor arm, HT leads changed last? Is the car overfuelling? Is there blackening of the spark plugs & exhaust pipe? Is there backfiring?  Check the easy stuff before changing the stuff that's hard to get to, do you know anyone with (& knows how to use) a code reader? What about a vault meter?

 

I had a similar problem to this and the code reader diagnosed a faulty O2 sensor in the manifold. A new one had already been fitted so this seemed strange. Looking into it further with we found that there seemed to be a break in the wire to the O2 sensor heater (as well as plenty of others) giving the intermittent fault. This is a common thing as the engine bay loom rubs against the bulkhead and manifold. I had mine repaired by an auto electrician.

 

See my thread thread here where the problem sounds very similar, especially see my posts 5/9/2010 & 21/5/2011.

 

http://www.minifinit...22&t=86339#wrap

Thank you! This is a continuation of my last thread, and you have also replied to me on Minifinity!  I will take a photo of my wires tomorrow for you I think there is actually a splt in one of them leading to the yellow bit under the air filter?

[QuintonNeaves]

As above, don't just start throwing parts at it. It gets expensive quickly, and may still not solve your issue. If the car is running fine when warm, then there is every chance it will be stepper motor related. Just so you understand what it does, basically it is your idle control - or at least part of it. It is a motor which is controlled by the ECU. It isn't a spinning motor, it is a stepper motor, which means that it can move in increments. As the motor and it's gearing are attached to a lever which acts on the throttle, it can effectively 'push' the throttle, in much the same way that you do with your foot on the pedal. The stepper motor is used by the ECU along with ignition timing to alter the idle speed of the engine. At cold start, the stepper is used more than when warm, to raise the idle speed during warm up. Once the car is warm, it is typically used to compensate for a drop in engine revs at idle due to electrical loading, such as headlights, demister etc, which put more load on the alternator resulting in a drag which lowers the idle speed.

 

Stepper motors on minis are known to give issues, mainly due to failure of solder joints on the circuit board inside, or sometimes failure of one or more of the coils of the motor itself. The first thing would be to establish if the stepper is working at all. One easy way to tell is that when you have the engine running then switch off the engine, the stepper motor will index so that it is in a good position for the next start.  You will be able to hear it doing this, it makes a clicking sound for a couple of seconds. Post back once you have checked this and we will be in a better position to advise.

 

As for the number of cranks before the car starts cold, I would say that is OK. My 92 cooper SPi also takes about 6 compressions (this will be what you mean) before starting. I initially thought that was odd, as I am sure my last car a 95 cooper SPi started quicker, however I discovered through experimenting that the time taken is due to the time it takes fuel to get into the inlet manifold. It's always the same number of compressions, has never changed so I am not worried about it and would suggest that you shouldn't be either. I find that a hot start is quicker - maybe 2 - 3 compressions.

Thank you, the stepper motor is working, a lot better now that it was as the garage have cleaned the whole thing up for m, before it was sticking a little. The only reason I was concerned about the number of compressions before the engine fires up is because when I first got the car it started first time, every time. Will this get worse as the days get colder?

[humph]

 

As above, don't just start throwing parts at it. It gets expensive quickly, and may still not solve your issue. If the car is running fine when warm, then there is every chance it will be stepper motor related. Just so you understand what it does, basically it is your idle control - or at least part of it. It is a motor which is controlled by the ECU. It isn't a spinning motor, it is a stepper motor, which means that it can move in increments. As the motor and it's gearing are attached to a lever which acts on the throttle, it can effectively 'push' the throttle, in much the same way that you do with your foot on the pedal. The stepper motor is used by the ECU along with ignition timing to alter the idle speed of the engine. At cold start, the stepper is used more than when warm, to raise the idle speed during warm up. Once the car is warm, it is typically used to compensate for a drop in engine revs at idle due to electrical loading, such as headlights, demister etc, which put more load on the alternator resulting in a drag which lowers the idle speed.

 

Stepper motors on minis are known to give issues, mainly due to failure of solder joints on the circuit board inside, or sometimes failure of one or more of the coils of the motor itself. The first thing would be to establish if the stepper is working at all. One easy way to tell is that when you have the engine running then switch off the engine, the stepper motor will index so that it is in a good position for the next start.  You will be able to hear it doing this, it makes a clicking sound for a couple of seconds. Post back once you have checked this and we will be in a better position to advise.

 

As for the number of cranks before the car starts cold, I would say that is OK. My 92 cooper SPi also takes about 6 compressions (this will be what you mean) before starting. I initially thought that was odd, as I am sure my last car a 95 cooper SPi started quicker, however I discovered through experimenting that the time taken is due to the time it takes fuel to get into the inlet manifold. It's always the same number of compressions, has never changed so I am not worried about it and would suggest that you shouldn't be either. I find that a hot start is quicker - maybe 2 - 3 compressions.

Thank you, the stepper motor is working, a lot better now that it was as the garage have cleaned the whole thing up for m, before it was sticking a little. The only reason I was concerned about the number of compressions before the engine fires up is because when I first got the car it started first time, every time. Will this get worse as the days get colder?

 

Separate from my knackered wiring loom, I had a stepper motor problem at the same time (made sorting either problem a pain in the ar$e).  I thought my stepper was working fine, turns out it was working intermittently and eventually stopped working completely. This wasn;t the motor itself, it was the motor drivers within the ECU that had failed. ECU out, off for checking and repair, put it back in and all sorted in 48 hours. This wasn't cheap (£100) so I'd keep listening out for the stepper working and establish it isn't before going down this route. This caused a fast idle on mine.

Edited by humph, 08 August 2015 - 05:31 PM.