Anyone got a spare stepper motor for sale/to borrow?
Discussion
My high idle problem continues. I've changed the AFM and it's had no effect. Once warm the car continues to idle at 2100rpm with either the clutch pedal pressed or no gear selected. I managed to get the AFM off eBay, but if the problem isn't the stepper motor then buying a new one is an expensive mistake. Does anyone have a spare stepper motor lying around that I could buy or borrow? I'm happy to refund any postage and include a little thankyou when I return the motor to you if you only want to lend it to me for a trial period.
Cheers
Cheers
I built a test rig for the stepper, that allows me to strip them apart, clean and test them if you want to pop it in the post (drop me a email if you do), but you can do some more simple tests to see if its working. First if the engine is running to fast, try clamping the air feed pipe to the stepper motor firmly shut, and see if the RPM drops. If it dose not you have an air leak around the plenum, throttle stuck part open or the base idle is far to high. As Quinny says if you can get the RPM to drop normally, disconnect the stepper, and then stop the engine and let it cool. Then remove the stepper, and with it reconnected, get someone to cycle the ignition on and off slowly(dont start) whilst you look at the stepper. It should retract as you turn the ignition OFF, and you should hear it buzz as it hits the end stop. It will only do this once, as from this point its fully wound back, ready for the next restart.
just sorted mine after months of fiddling with stepper motor. i had the same problem as yours.
it turned out to be i think its called the throttle censor it was not lined up properly, its on the plenum opposite side to the throttle cable with two screws and a couple of wire going in to it. just loosen the screws and turned it anti clockwise NOW idles just under 1000 worth a try hope this makes sense.
it turned out to be i think its called the throttle censor it was not lined up properly, its on the plenum opposite side to the throttle cable with two screws and a couple of wire going in to it. just loosen the screws and turned it anti clockwise NOW idles just under 1000 worth a try hope this makes sense.
floyd12345 said:
just sorted mine after months of fiddling with stepper motor. i had the same problem as yours.
it turned out to be i think its called the throttle censor it was not lined up properly, its on the plenum opposite side to the throttle cable with two screws and a couple of wire going in to it. just loosen the screws and turned it anti clockwise NOW idles just under 1000 worth a try hope this makes sense.
Just tucked the little fella up in the garage - wish I'd seen your post before. Thank you for replying. I think I have just wasted my time a bit because I remembered incorrectly what Quinny and Blitzracing told me to do. I warmed up the car, turned it off, removed the stepper motor started it up. It started up and the revs fell as quickly as they rose. The only way to stop it cutting out was to blip the throttle. it turned out to be i think its called the throttle censor it was not lined up properly, its on the plenum opposite side to the throttle cable with two screws and a couple of wire going in to it. just loosen the screws and turned it anti clockwise NOW idles just under 1000 worth a try hope this makes sense.
Tomorrow I will print off all your advice and go through the steps properly.
You must disconnect the motor while your engine is running otherwise when you turn off your engine the stepper motor parks itself at it's maximum opening ready for the next engine start.
If your idle stays stable then you know it may be stepper motor related. However if you leave it disconnected like I did for about 12 months the engine won't tick over when cold for the first couple of minutes but will run fine after that.
I have just replaced mine with one from a guy on Ebay. It cost me 20 quid INCLUDING postage so I thought it was worth a punt. I stuck it on this morning and found it didn't work.
After a bit of investigation I found that the probe thread was longer on the new one than the old so it was more or less fully closed all the time. So I removed the centre probe from the old unit and pushed it into the new unit and it now works perfectly. I also had to remove a key way tab to allow the plug to fit correctly but for 20 quid I'm well chuffed.
Here's the guy if you want to order one. It arrived within 48 hours.
http://cgi.ebay.co.uk/Air-Idle-Control-Valve-Land-...
Hope this helps.
Paul
If your idle stays stable then you know it may be stepper motor related. However if you leave it disconnected like I did for about 12 months the engine won't tick over when cold for the first couple of minutes but will run fine after that.
I have just replaced mine with one from a guy on Ebay. It cost me 20 quid INCLUDING postage so I thought it was worth a punt. I stuck it on this morning and found it didn't work.
After a bit of investigation I found that the probe thread was longer on the new one than the old so it was more or less fully closed all the time. So I removed the centre probe from the old unit and pushed it into the new unit and it now works perfectly. I also had to remove a key way tab to allow the plug to fit correctly but for 20 quid I'm well chuffed.
Here's the guy if you want to order one. It arrived within 48 hours.
http://cgi.ebay.co.uk/Air-Idle-Control-Valve-Land-...
Hope this helps.
Paul
You worry me! The keyway tab stops the keywayed shaft from rotating when the motor turns, so without it Im surprised the cone moves in and out at all. If you do have a problem with the length of the shaft, Id pack out the screw thread on the stepper body itself with big washers (like the copper one used for the sump plug) and PTFE so you move the whole stepper body back out a bit to give you more movement. The cheap Ebay jobbie I bought let air in aroun the motor body, and the idle was all over the place. Im still quite happy to strip and clean /test your old unit out for the cost of a pint and postage if you want.
Servicing the stepper motor.
I have now perfected a way of getting them to bits to clean, without damage:
1) Get the car warm
2) Remove the stepper from the plenum and reconnect it.
3) Block the hole left by the stepper with anything that will be air tight. You just need to block the screw thread, no more.
3) Hold the stepper in your hand, so you can catch the central cone and spring when it comes out.
4) Get someone to start the car. Without the stepper in place it will rev at around 2k- 2.5k (This is noisy!!), but the ECU will try to slow it down by powering the stepper motor and pushing cone outwards. It will do this in a series of pulses, a few seconds apart, until the cone and spring drop out. (assuming they are not completely stuck). It may take a bit of manual help to get the cone to fully release. Now stop the engine and let it cool.
6) Clean all the muck of the shaft, and lightly lubricate the screw thread inside the motor.
7) To reassemble, wind the shaft back into the motor so far, but align the slot in the shaft with the plastic keyway as best you can by rotating the shaft in its screw thread
8)With the engine cool, then reconnect the stepper motor. Power cycle the ignition on and off, (don't start) and the ECU will try to pull the shaft back in each time the ignition is turned OFF. This is the slightly tricky bit, as if the keyway and shaft are not quite aligned it wont pull home, so you may need a few attempts.
I have now perfected a way of getting them to bits to clean, without damage:
1) Get the car warm
2) Remove the stepper from the plenum and reconnect it.
3) Block the hole left by the stepper with anything that will be air tight. You just need to block the screw thread, no more.
3) Hold the stepper in your hand, so you can catch the central cone and spring when it comes out.
4) Get someone to start the car. Without the stepper in place it will rev at around 2k- 2.5k (This is noisy!!), but the ECU will try to slow it down by powering the stepper motor and pushing cone outwards. It will do this in a series of pulses, a few seconds apart, until the cone and spring drop out. (assuming they are not completely stuck). It may take a bit of manual help to get the cone to fully release. Now stop the engine and let it cool.
6) Clean all the muck of the shaft, and lightly lubricate the screw thread inside the motor.
7) To reassemble, wind the shaft back into the motor so far, but align the slot in the shaft with the plastic keyway as best you can by rotating the shaft in its screw thread
8)With the engine cool, then reconnect the stepper motor. Power cycle the ignition on and off, (don't start) and the ECU will try to pull the shaft back in each time the ignition is turned OFF. This is the slightly tricky bit, as if the keyway and shaft are not quite aligned it wont pull home, so you may need a few attempts.
floyd12345 said:
just sorted mine after months of fiddling with stepper motor. i had the same problem as yours.
it turned out to be i think its called the throttle censor it was not lined up properly, its on the plenum opposite side to the throttle cable with two screws and a couple of wire going in to it. just loosen the screws and turned it anti clockwise NOW idles just under 1000 worth a try hope this makes sense.
Sounds like you are refering to the throttle potentiometer which sends a voltage signal back to the ECU to indicate the actual throttle position. The ECU has a predetermined set of voltage values, so for example, a 2V signal from the pot might equate to 2500rpm so the ECU then knows how long to open the injectors for.it turned out to be i think its called the throttle censor it was not lined up properly, its on the plenum opposite side to the throttle cable with two screws and a couple of wire going in to it. just loosen the screws and turned it anti clockwise NOW idles just under 1000 worth a try hope this makes sense.
The throttle pot, at idle, should be set to 0.33-0.34V therefore if the voltage reading from the pot is a long way out it could well result in the excess tickover being described. It is not unusual for the pot to need minor adjustment but if this is the cause it would mean the unit is either faulty, the securing screws have worked loose or it has been inadvertently being knocked.
Bodders
Sorry guys just to clear things up. I mean the tab on the plug not the motor itself, the one that is meant to stop you fitting it the wrong way round or into a different plug.
There are two on mine which are down inside where the sockets are and they have a corresponding slot in the plug on the loom.
I think it's just there to make you pay more for a TVR part
Anyway just crushed them with some snipe nose pliers and it fitted and worked fine.
There are two on mine which are down inside where the sockets are and they have a corresponding slot in the plug on the loom.
I think it's just there to make you pay more for a TVR part
Anyway just crushed them with some snipe nose pliers and it fitted and worked fine.
Bodmin said:
floyd12345 said:
just sorted mine after months of fiddling with stepper motor. i had the same problem as yours.
it turned out to be i think its called the throttle censor it was not lined up properly, its on the plenum opposite side to the throttle cable with two screws and a couple of wire going in to it. just loosen the screws and turned it anti clockwise NOW idles just under 1000 worth a try hope this makes sense.
Sounds like you are refering to the throttle potentiometer which sends a voltage signal back to the ECU to indicate the actual throttle position. The ECU has a predetermined set of voltage values, so for example, a 2V signal from the pot might equate to 2500rpm so the ECU then knows how long to open the injectors for.it turned out to be i think its called the throttle censor it was not lined up properly, its on the plenum opposite side to the throttle cable with two screws and a couple of wire going in to it. just loosen the screws and turned it anti clockwise NOW idles just under 1000 worth a try hope this makes sense.
The throttle pot, at idle, should be set to 0.33-0.34V therefore if the voltage reading from the pot is a long way out it could well result in the excess tickover being described. It is not unusual for the pot to need minor adjustment but if this is the cause it would mean the unit is either faulty, the securing screws have worked loose or it has been inadvertently being knocked.
Bodders
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