Something I noticed today and haven't before
 

I was sitting with the car at idle, it was fluctuating between 500 and 800 revs going brum, brum, if you know what I mean. When I put the windscreen wipers off, the heaters off, the rear windscreen demister off and the lights off it went to 600 revs and stayed there, no more brum brum, just a steady purr. Is this normal?

I can smell burning...........

Sounds perfectly normal to me, you have reduced the load on the charging system so it no longer requires the higher revs.....as to the burning put the fag out!

The burning is NOT normal, but on the other hand if you are at idle and you have alot of things switch on at once it will put a load on your alt to keep your battery charge hence the brum brum, you may need to get your battery and alternator checked as the smell may be coming from ether of them.

hth

Your car should be ticking over at a visible and constant 750 RPM regardless of the electrical load. There may be a slight momentary fluctuation as the ECU works to compensate for any extra load on the engine by balancing the RPM rate.
Smell of burning in a car is not normal. Get it checked asap.

I must admit mine is virtually on about 700rpm with the occasional fluctuation.

Yeah, it usually ticks over at 600rpm no matter what. I'll keep an eye on it.

Should have said I can smell burning in the living room but I think it's cos I've put my fire light on for the first time in about a year.

So there is no burning in the 75?

Scoot, do explain yourself a little more clearly. There's me thinking your car is going to burst into flames.
I think I need an aspirin and a lie down :)

PMSL....the subtleties of Scooterchick's formatting eluded you (and others)Grey Ghost....

The last time I had a 'brum, brum' effect from the engine was a day before the cambelt went. This was on a 400 diesel which had been 'serviced' by a dubious character, who reckoned to have replaced the belt 40K miles earlier. This and your burning smell sounds familiar. I'd have it checked NOW.