Stepper motor - is it OK?
Discussion
Have been having idle probs for a few weeks. Sometimes even with engine hot, it will idle at 1600.
Idle speed usually drops after the car has been stationary for about 30 secs, but not always.
Decided to clean the stepper motor - so read Bible and cleaned it (a little carbon round the seat of the valve head but not much) but idle problem still present. Also cleaned round butterly valve.
I noticed that the sprung plunger at the end of the stepper motor did not move - it seemed to be fixed in one position. I re-connected it to the power supply whilst out of its housing and no click, or movement when power turned on. Is this normal or might the stepper motor be dead?
Thanks for any advice.
Idle speed usually drops after the car has been stationary for about 30 secs, but not always.
Decided to clean the stepper motor - so read Bible and cleaned it (a little carbon round the seat of the valve head but not much) but idle problem still present. Also cleaned round butterly valve.
I noticed that the sprung plunger at the end of the stepper motor did not move - it seemed to be fixed in one position. I re-connected it to the power supply whilst out of its housing and no click, or movement when power turned on. Is this normal or might the stepper motor be dead?
Thanks for any advice.
Then perhaps it's something other than the stepper.
I have long maintained that in the possibilities (and there are a number!) that lead to high idle you should include a look at the coolant level. I have always known when my coolant needs a top up because the idle pattern changes and, unless I'm much mistaken, there is some logic behind this. If the sensor doesn't get a water temperature (because of air in the system) it thinks that the engine isn't warm and tries to treat it like it's first fired up. Result is a very confused ECU and idling at up to 2000.
That's what 50,000 miles leads me to believe anyway.
But there are probably 101 other factors!!!!!
I have long maintained that in the possibilities (and there are a number!) that lead to high idle you should include a look at the coolant level. I have always known when my coolant needs a top up because the idle pattern changes and, unless I'm much mistaken, there is some logic behind this. If the sensor doesn't get a water temperature (because of air in the system) it thinks that the engine isn't warm and tries to treat it like it's first fired up. Result is a very confused ECU and idling at up to 2000.
That's what 50,000 miles leads me to believe anyway.
But there are probably 101 other factors!!!!!
prop said:
I noticed that the sprung plunger at the end of the stepper motor did not move - it seemed to be fixed in one position. I re-connected it to the power supply whilst out of its housing and no click, or movement when power turned on. Is this normal or might the stepper motor be dead?
Thanks for any advice.
this is something i cant figure out. I know a mates griff had a plunger that was fixed in position. However, the stepper motor on my chim has one that "wobbles" around a bit. anyone able to confirm how it is supposed to be?
beano500 said:
I have long maintained that in the possibilities (and there are a number!) that lead to high idle you should include a look at the coolant level. I have always known when my coolant needs a top up because the idle pattern changes and, unless I'm much mistaken, there is some logic behind this. If the sensor doesn't get a water temperature (because of air in the system) it thinks that the engine isn't warm and tries to treat it like it's first fired up. Result is a very confused ECU and idling at up to 2000.
It's interesting that these topics often pop up at just the right time. I've been experiencing idling problems identical to those described and so whipped out the stepper motor for a clean at the w/e. It was good and black, so after a good clean I thought I must have fixed the problem. There is certainly less lumpiness at the low end of the rev range now, but idling is still high and after a quick run out yesterday water temperature was creeping up towards 100 !
Next job on the list then is the butterfly valve AND the coolant level.
Prop and Shnozz are both asking the specific question that I have not seen answered, and am eager to know.
“Should the plunger of the stepper motor move when it is out of the car?”
(Assuming that it must move when in the car, powered up and at running temperature – otherwise what’s its purpose!)
All I know is that when I cleaned mine, it did not move with out some considerable pressure, and then only slightly.
(Sorry I can’t be more help)
….so Dear Doctor, mine and Prop’s are stiff and Shnozz’s is flaccid. Which of us need treatment?
“Should the plunger of the stepper motor move when it is out of the car?”
(Assuming that it must move when in the car, powered up and at running temperature – otherwise what’s its purpose!)
All I know is that when I cleaned mine, it did not move with out some considerable pressure, and then only slightly.
(Sorry I can’t be more help)
….so Dear Doctor, mine and Prop’s are stiff and Shnozz’s is flaccid. Which of us need treatment?
I've just had similar problems with mine.
Removed stepper motor and reconnected plug
Blocked hole up where stepper motor was
Started engine
Engine idles very fast - stepper motor moves plunger out to block the air leak into plenum to slow it down.
When you switch engine off,motor will pull plunger back in - this is the buzzing noise you hear when switching ignition off.
I left my engine running for a few minutes and the motor drove the plunger off completely !!!!
but I managed to get it back in !!
not sure if this is a good thing to do or not but it worked fine for me
cheers Andy
Removed stepper motor and reconnected plug
Blocked hole up where stepper motor was
Started engine
Engine idles very fast - stepper motor moves plunger out to block the air leak into plenum to slow it down.
When you switch engine off,motor will pull plunger back in - this is the buzzing noise you hear when switching ignition off.
I left my engine running for a few minutes and the motor drove the plunger off completely !!!!
but I managed to get it back in !!
not sure if this is a good thing to do or not but it worked fine for me
cheers Andy
I put a bit of copper grease (not to much)on the contacts of the plug that goes into the stepper motor. This helped also, idling is smoother now. I reckon that the high temps under the bonnet corrode contacts quickly, giving higher resistance, therefore the stepper motor reacts not the way it should. Anyway all theory, but on mine it made a small improvement.
Fred
Fred
thatch said:
“Should the plunger of the stepper motor move when it is out of the car?”
All I know is that when I cleaned mine, it did not move with out some considerable pressure, and then only slightly.
(Sorry I can’t be more help)
….so Dear Doctor, mine and Prop’s are stiff and Shnozz’s is flaccid. Which of us need treatment?
IIRC the actuator will only move under load. (plugged in)
Agian IIRC It is fixed in it's unplugged condition.
So sounds like Shnozz needs the two lolly pop sticks and the reel of selotape
Big Al. said:
“Should the plunger of the stepper motor move when it is out of the car?”
All I know is that when I cleaned mine, it did not move with out some considerable pressure, and then only slightly.
(Sorry I can’t be more help)
….so Dear Doctor, mine and Prop’s are stiff and Shnozz’s is flaccid. Which of us need treatment?
IIRC the actuator will only move under load. (plugged in)
Agian IIRC It is fixed in it's unplugged condition.
So sounds like Shnozz needs the two lolly pop sticks and the reel of selotape
jeez, old age comes to all of us eh....
well its still running ok, so if it aint broke...
catretriever said:
I have long maintained that in the possibilities (and there are a number!) that lead to high idle you should include a look at the coolant level.
Next job on the list then is the butterfly valve AND the coolant level.
Apologise for the minor thread hijack but I just wanted to post and say that beano500's tip was spot on for me at least. Having cleaned the stepper I found that the car was suddenly overheating and the fans weren't cutting in when expected. I had only recently changed the otter switch so was feeling a bit peeved that I may have got a dodgy one....anyhew a quick check showed that the coolant level was indeed way too low. After a top up all lumpiness has gone, the car idles nicely around 900rpm, and the temperature is back under control. Hurrah!
Mental note to self..check coolant more frequently. It seems the stuff just evaporates into thin air
How about resetting the ECU?
After a recent problem with my griff, changing the suspect components (ignition in this case) made no difference - I found that I had to reset the ECU (disconnect and re-connect) which then made everything work fine. This is because the ECU "learns" and re-adjusts/optimises the fuel injection based on the data coming from the various sensors around the engine. So if something has gone wonky (i.e. out of spec), the ECU adjusts itself to the wonkiness and gets itself in a pickle such that when you replace said wonky part with a good part, the ECU is still screwed up.
The moral of the story (for me at least) is that when you replace a suspect part, or make other changes,(e.g. cleaning the stepper motor)and it doesn't immediately fix the problem, reset the ECU. You've got nothing to lose except the fault codes which are lost when you reset - but if you have no intention of getting a fault code reader and looking at these, then they're useless anyway - and further, if the fault is still there, then the code will be re-logged.
I dummo, what do you guys think?
Steve
After a recent problem with my griff, changing the suspect components (ignition in this case) made no difference - I found that I had to reset the ECU (disconnect and re-connect) which then made everything work fine. This is because the ECU "learns" and re-adjusts/optimises the fuel injection based on the data coming from the various sensors around the engine. So if something has gone wonky (i.e. out of spec), the ECU adjusts itself to the wonkiness and gets itself in a pickle such that when you replace said wonky part with a good part, the ECU is still screwed up.
The moral of the story (for me at least) is that when you replace a suspect part, or make other changes,(e.g. cleaning the stepper motor)and it doesn't immediately fix the problem, reset the ECU. You've got nothing to lose except the fault codes which are lost when you reset - but if you have no intention of getting a fault code reader and looking at these, then they're useless anyway - and further, if the fault is still there, then the code will be re-logged.
I dummo, what do you guys think?
Steve
Advice needed!
I attempted to clean stepper motor and found that the conical plunger rotates, and can be screwed out completely. I put it back together and found that the motor gives a little "kick" when the ignition is switched on (I guess it's the motor coils enrgising?)and retracts the plunger (i.e. opens the airway) when the ignition is turned off, so it seems to be operating ok.
However, it looks to me like it is should not rotate because there are splines in the plunger. Anyhow, the damn thing won't tick over now, the engine just dies.
1/ should it rotate?
2/ if engine dies on tick over, does this mean air starvation i.e. plunger fully extended blocking airway?
I attempted to clean stepper motor and found that the conical plunger rotates, and can be screwed out completely. I put it back together and found that the motor gives a little "kick" when the ignition is switched on (I guess it's the motor coils enrgising?)and retracts the plunger (i.e. opens the airway) when the ignition is turned off, so it seems to be operating ok.
However, it looks to me like it is should not rotate because there are splines in the plunger. Anyhow, the damn thing won't tick over now, the engine just dies.
1/ should it rotate?
2/ if engine dies on tick over, does this mean air starvation i.e. plunger fully extended blocking airway?
red griff 500 said:sounds like youve not put the plunger back in the same position.youll need somone else to tell you what its extended length should be by measuring thiers-sorry,cant help here as mine is 200 miles way at mo.obviously you need to re-set yours under the same conditions as the ok one your using for std so do it when the engine is stone cold and hasnt been used for 12hours for instance.you could try trial and error,but itll get frustrating as itll be difficult to get just the right tickover speed.it sounds like your plunger is too far extended,not allowing enough by-pass air for starters.
Advice needed!
I attempted to clean stepper motor and found that the conical plunger rotates, and can be screwed out completely. I put it back together and found that the motor gives a little "kick" when the ignition is switched on (I guess it's the motor coils enrgising?)and retracts the plunger (i.e. opens the airway) when the ignition is turned off, so it seems to be operating ok.
However, it looks to me like it is should not rotate because there are splines in the plunger. Anyhow, the damn thing won't tick over now, the engine just dies.
1/ should it rotate?
2/ if engine dies on tick over, does this mean air starvation i.e. plunger fully extended blocking airway?
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