Monday 19 November 2007

Starting a Micra on a Cold Morning

06:30 this morning, the car wouldn't start.

We own an old Micra. It's gold, has seen better days, but gets us around, and was free. What more can I say.
Anyway, there is a problem with old Micras which is probably quite costly for Micra drivers over time; in cold weather the car won't start for love nor money. We had owned the car for only a couple of months when we first encountered this, and had to call the AA out because of it.
The problem is that the engine management system (yes, there is one in a Micra!) reads the ambient temperature incorrectly and spurts too much petrol into the engine when the ignition is turned, effectively flooding the engine. Modern engines are quite well sealed which means that the petrol doesn't evaporate quickly. Plus, the engine will continue to inject too much petrol into the engine if the temperature stays about the same.
How does one fix this problem? I have read on the odd forum that buying a new temperature detection unit (thermometer to you and me) can fix the problem, but there is no guarantee. The easiest way to get around this issue is to pull out the engine management fuse and start the engine. This burns off the excess fuel, and warms up the engine bay a bit. Switch off the engine, replace the fuse, and the engine should start as normal. It's not the most convenient solution, but will prevent people from buying an unnecessary bit of kit for an ageing model of car.

UPDATE - I have noticed quite a few hits on this article since writing it. If you find it useful (or even not) please leave a comment so others may gain from your knowledge/experiences too.
SheyMouse

3 comments:

Anonymous said...

Thanks for this helpful tip! My wife's beloved old Micra (she won't sell it) has suffered from this problem occasionally. I find the cold-day flooding problem is much less likely to happen if you run with fresh spark plugs. If you get tired of pulling out the fuse, it may be time for a service.

Anonymous said...

Where abouts is the fuse? My micra won't start first thing but leave it afew hours and she will fire up!!

Shey said...

The fuse "box" is behind a panel down and to the right of the steering wheel.
You will have to look at the diagram on the inside of the cover for precisely which fuse will disable the fuel management.