Car cutting out when changing down to 3rd

[Richard Jay]

My Brava 1.6 mk1 has this annoying habit of cutting out on me when I try to change down from 4th gear to 3rd gear. When I engage the clutch the engine dies and the immobiliser comes in .... not exactly ideal when approaching a 90degree turn as happened last week !!

It used to happen just once or twice a year after long motorway journeys; now it's happened twice in the past week including at the end of a 30 minute journey. On every occasion the car is well warmed up - it doesn't just happen in Winter. Sometimes the battery warning light will come on momentarily but if I disengage the clutch quick enough the engine doesn't cut out.

This is a very difficult thing to show a mechanic so I'm asking here for pointers. I have noticed that after the car has been running for some time, it idles extremely low, which I thought might be related. However I have reset the ECU on several occasions hoping that the car would relearn this.

I should mention that I took the car to Fiat earlier on this year regarding a (possibly related) problem with starting on cold winter mornings, where it would always start but I'd have to give it lots of gas pedal to get it to come up to normal idling. They put it on their computer and could find no fault.

 

[Tom]

Define 'idles really low'.

 

[Anonymous]

When starting the car it's at 1500-ish but within a few minutes the needle is about as low as it can go. You can hear that it is idling very low - I'm not a mechanic so can't describe it any better than that.

 

[Tom]

Numbers would be useful.

 

[Anonymous]

I've never seen it go lower than 1000 when stationary ...

 

[Tom]

Normal idle is 850 so 1000 is high.

 

[Anonymous]

My revs dial is in 1000 increments so I couldn't possibly tell you whether it's 1000, 900, or whatever.

 

[Tom]

Are there no little graduations on the dial?

 

[Anonymous]

No there's nothing below "1" other than empty space ....

 

[Tom]

If its not going below 1 then there is a fault. Tell this detail to your mechanic. It should idle happily below 1.

 

[Anonymous]

But Fiat have already checked it out, as have a local garage. I don't ever remember seeing the needle fall below 1000 and if that was the problem I would have expected it to be spotted pretty easily !

 

[Tom]

Mechanics can be quite thick, sometimes you need to point things out to them.

It could be the symptoms of an air leak or a faulty idle valve.