Discussion
My Chim (sometimes) won't idle smoothly -especially when the car is cold. When I first start up it is fine, but after a minute of so of driving it will no longer idle smoothly.
Instead it will fluctuate between 1000 & 2000 rpm (as if I am revving it myself), then after 20 seconds or so it will rev up to about 2500 rpm and then will start to idle correctly.
However as soon as I move off again, the next time I come to a halt the same thing happens.
I know 99% of problems are caused stepper motor - mine a recent replacement (previous owner) and has cleaning it (regularly) hasn't helped.
So:
i) Is this lumpy idling normal?
ii) Is it the stepper motor?
iii) What else could it be?
It's not a major problem, but it doesn't half intimidate the average Gti driver at traffic lights as I appear to be constantly revving the engine
Instead it will fluctuate between 1000 & 2000 rpm (as if I am revving it myself), then after 20 seconds or so it will rev up to about 2500 rpm and then will start to idle correctly.
However as soon as I move off again, the next time I come to a halt the same thing happens.
I know 99% of problems are caused stepper motor - mine a recent replacement (previous owner) and has cleaning it (regularly) hasn't helped.
So:
i) Is this lumpy idling normal?
ii) Is it the stepper motor?
iii) What else could it be?
It's not a major problem, but it doesn't half intimidate the average Gti driver at traffic lights as I appear to be constantly revving the engine
Sometimes mine's like that too.
If I start it up and leave on tick-over of a few minutes while I load the car or something it seems to be OK, or, as my dealer taught me, when you start it 'purge' the engine, a couple of blips on the throttle should suffice, nothing too mad, I generally do that and then hold it at about 1500rpm for a few seconds (pause for breath!).
I'm told it's something to do with the lambda sensor and the ECU, the engine pours petrol in to get the engine started and the lambda goes 'OI too much fuel!' the ECU then backs off the fuel flow a little then the sensor goes 'OI not enough fuel!' and so it goes on.
'Purging' blows through the excess fuel that is used to start the engine which doesn't confuse the cleaver little electric gizmo's.
Anyway, that's what I've been told - it could all be crap.
If I start it up and leave on tick-over of a few minutes while I load the car or something it seems to be OK, or, as my dealer taught me, when you start it 'purge' the engine, a couple of blips on the throttle should suffice, nothing too mad, I generally do that and then hold it at about 1500rpm for a few seconds (pause for breath!).
I'm told it's something to do with the lambda sensor and the ECU, the engine pours petrol in to get the engine started and the lambda goes 'OI too much fuel!' the ECU then backs off the fuel flow a little then the sensor goes 'OI not enough fuel!' and so it goes on.
'Purging' blows through the excess fuel that is used to start the engine which doesn't confuse the cleaver little electric gizmo's.
Anyway, that's what I've been told - it could all be crap.
I've had corroded connectors (probably through a previous owner having it steam cleaned - or maybe just some of our best weather conditions getting all round the engine bay) which meant that the signals from the sensors were not getting to the ECU.
Ultimately it got to the point where the engine just thought that unburnt fuel was getting through to the cat while it was warming up and, of course, it then goes into shut down mode!
Of course, you go through several weeks of something being not quite right. Until it gets to be a repeated problem you (and your garage) may be stumped.
Hope if you have got a developing problem, it's nothing more costly than this or a stepper motor clean.
Ultimately it got to the point where the engine just thought that unburnt fuel was getting through to the cat while it was warming up and, of course, it then goes into shut down mode!
Of course, you go through several weeks of something being not quite right. Until it gets to be a repeated problem you (and your garage) may be stumped.
Hope if you have got a developing problem, it's nothing more costly than this or a stepper motor clean.
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