its probably the idle control valve doing its job...opening and closing to vary the idle via the ecu as it should...
Z3 M IDLE SPEED PROBLEM
- Thread starter Glen
- Start date
this may help to show how it works...
http://ricksfreeautorepairadvice.com/how-does-an-idle-air-control-valve-work/
http://ricksfreeautorepairadvice.com/how-does-an-idle-air-control-valve-work/
Hi Thanks for the post.
Before I bought the M I had the double vanos 2.8 and carried out the inlet manifold upgrade with adapter plate and modified disa valve.All went fine ,however upon starting ,the engine would not idle below 2200rpm . Needless to say the problem was a stuck idle control valve.cleaned it with some carb cleaner and all was fine!
- Joined
- Dec 8, 2011
- Points
- 145
I don't think it is the ECU. One line of code is unlikely to stop working.
The idle control valve is a definite possibility, but so is...
split hose
emissions pump
loose jubilee clip
sticking throttle butterfly on one of the throttle bodies
sticky throttle cable
VANOS diaphragm spring tension
dirty VANOS solenoid
leaking VANOS solenoid seals
...
You really need to study some live data from a specific BMW software program, like TestO (which is free).
The idle control valve is a definite possibility, but so is...
split hose
emissions pump
loose jubilee clip
sticking throttle butterfly on one of the throttle bodies
sticky throttle cable
VANOS diaphragm spring tension
dirty VANOS solenoid
leaking VANOS solenoid seals
...
You really need to study some live data from a specific BMW software program, like TestO (which is free).
- Joined
- Dec 8, 2011
- Points
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I went for a drive this afternoon and the revs definitely return to 800rpm from any rev setting AFTER the engine has warmed up.
BEFORE the engine is warm, the revs return to around 1100rpm. This is definitely to do with cold start as you can smell the excess fuel when the engine is cold, but not when it is warm.
BEFORE the engine is warm, the revs return to around 1100rpm. This is definitely to do with cold start as you can smell the excess fuel when the engine is cold, but not when it is warm.
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- Oct 19, 2014
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- Model of Z
- 2.2i Sport
So it could even be some form of temperature sensor problem. Don't know where that would be, though.
Hi
That is exactly what I would expect to see.Took mine out today.70mph into neutral ,rpm down to 1000rpm coasting all the way down to a standstill on stopping straight down to 800rpm !
Did notice that the car was not at full temp after being out for over an hour plugged in diagnostic tool and flagged up 4e temp sensor coolant fault, renewed sensor last year just starting to wonder if I have a faulty thermostat throwing the sensor,bit of a long shot but running out of ideas
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- Dec 8, 2011
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If diagnostics indicate a sensor problem, that is where I would concentrate my efforts.
Was it a BMW sensor or non-OEM? BMW sensors are very good, non-OEM are notoriously bad.
[edit] Why would a faulty thermostat show up on diagnostics? I'd suspect the sensor or the wiring to it.
Was it a BMW sensor or non-OEM? BMW sensors are very good, non-OEM are notoriously bad.
[edit] Why would a faulty thermostat show up on diagnostics? I'd suspect the sensor or the wiring to it.
I don’t know Pingu maybe the brain expects certain temperatures after a set period of time of the engine running and if not a temperature sensor error Is logged. Maybe just a theory that sort of made sense.
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- Dec 8, 2011
- Points
- 145
Did your problem sort itself with a new thermostat? If so, OP should try that.
A lovely job - NOT.
Yes Pingu I know I’m not on your level of expertise just a cheap option to consider.
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If it worked for you, it's a good solution to try
Cheers Pingu, a pain in the ass job to do but was worth while for me changing the water pump, belts, worn pulley wheels, clean up the tensioners, clean the rad and flush it. While that lot is out the way a good time to change vanos seals, bolts and gaskets if required while the space is there so one silver lining.
