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I have a 1986 peugeot 205 with a Mi16v engine from a 405 that was put in about 4 years ago. The car has never idled properly and we have been searching for an answer the whole time we've owned the car. Basically the car will not idle when its cold it stalls as soon as you take your foot off the power. Once warmed up it seems to idle fine if a little high. I have ruled out the idle speed control valve because it works if I connect it directly to the battery, but when connected to the car it just hums. I've checked the voltage to the idle valve and it reads 12v. The problem seems to be the switching of the idle control valve. For some reason it isn't getting the right signal to turn on or off. Coolant sensor was changed and this did not affect anything apart from increase the fuel consumption so I've put the old one back in. Coolant sensor is getting 5V at the pins. Could it be this or maybe the tps, I'm not sure how to check this so if anyone has some advise on voltages or resistances I should be checking please contact me. Is there anything else that switches the idle valve? I don't have the engine with the lambda sensor and SAD. Please help this is driving me mad!
Edited by 205puglet on 28/09/2009 at 19:02
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>but when connected to the car it just hums.
This sounds like a dodgy stepper motor.
Have you tried a know good replacement?
If you remove the valve and switch on the ignition does it move?
Kevin...
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No the valve doesn't move at all when plugged in, just makes that electrical humming noise like I said. I bought a new valve thinking this was the problem but it behaves in exactly the same way as the old one. I don't think there is anything wrong with the valve because it does move when connected to the battery, but I haven't tried a known good one yet.
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How many connector pins does it have?
Is it a stepper motor (I don't know the idle control on a Mi16)?
Is the idle high with the valve removed or manually retracted?
Kevin...
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I suspect (Pugs really aren't my thing) it's a Bosch rotary idle actuator, under the control of a Motronic ECU.
It should buzz when it's working - it is driven by a PWM signal, and is a simple motor connected to a sprung valve rather than a stepper motor. On a scope, you should see a square wave that vaies the on/off ratio as engine speed changes.
To be driven in idle mode, the ECU needs to have a valid speed signal, and a throttle position signal which indicates the car is idling. Once the engine has come up to temperature, this basic idle function will be augmented by overrun fuel cut-off.
The idle actuator is a 2 pin device, and as such, there may be the possibility to wire it up incorrectly, as the system will have a few 2 pin Bosch type plugs.
However, as I know nowt about Pugs, I could be wrong.
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Yes it is a 2 pin connector, it will only fit in one way, so I don't think the wires are crossed. It maybe a sprung valve like you say because if I move it by hand it does feel like a spring. Does anyone know how I can check the tps, temperature sensor and vehicle speed sensor?
Thanks again.
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is the air valve seateing correctly they tend to wear where they seat if yours has a grove worn into it try cleaning up with a fine wet an dry or if to deep replace
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If I remember correctly (used to have a BX with the same engine) there is a throttle position swich on the butterfly housing. It signals closed throttle and wide open throttle. I would be looking for correct operation of the switch. Also from memory there is a vacuum port in the same area with a very small hole. It is either part of the breather system or fuel pressure regulation. It is very prone to blockage.
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