Something in the Octavia is making a ticking noise as interference over the radio. It is linked to engine speed but only when it is under load. As soon as you lift off it drops in speed, so its almost as if its linked to the ammount of throttle you have applied.

Now, could it be the fuel pump ?

from problems with car stereo problems I have encountered it is called alternator wine and is often due to a bad earth somewhere, not much help I know but something to look for...

I dont think it is alternator wine as I had that on my Nove and it sounded a little different. This it like a ticking noise.

heater matrix aint it?

Its not a rattle, its interference over the stereo.

Something in the Octavia is making a ticking noise as interference over the radio. It is linked to engine speed but only when it is under load. As soon as you lift off it drops in speed' date=' so its almost as if its linked to the ammount of throttle you have applied.

Now, could it be the fuel pump ?[/quote']

You could be onto something there. If you've not already done so, how about revving it in neutral to see what that does to the ticking? The engine won't be under any amount of load as such, of course, but you'll be able to vary the revs to your heart's content.

Mind you, I don't know how fast your fuel pump would actually turn. The best I can come up with is from the Dodge 50 series truck handbook, which implies they turn at upwards of 3000rpm. If this was the case, I'd expect one 'tick' per revolution, which would work out as 50Hz (the same pitch as the 'hum' from a mains AC/DC adaptor) So you might expect a buzzing or humming sound, rather than a distinct tick-tick-tick...?

Without going out in the car, I'd say that around motorway cruising speed (must be about 3500 rpm?) it is about 240 ticks per/min.

I noticed this morning that when I put my foot down and the car is on full boost the noise stops.

Without going out in the car' date=' I'd say that around motorway cruising speed (must be about 3500 rpm?) it is about 240 ticks per/min.

I noticed this morning that when I put my foot down and the car is on full boost the noise stops.[/quote']

So that's something like the rate of an old-skool clockwork watch ticking, in that case? Based on my (very limited) knowledge, I'd say it's not the fuel pump then!

Don't know enough about turbos to give any advice really, but after what you said about the noise disappearing at full boost, I did a bit of research on How Stuff Works. I'd always thought the waste gate was open when the turbo was off-boost, allowing the exhaust gas to bypass the turbine. But apparently the wastegate opens at maximum boost, to prevent the turbo spinning too fast. I have absolutely no idea whether the waste gate is just held closed by a simple spring (like a pressure relief valve on a boiler), or whether something electronic controls when it opens or closes. If it is something electronic, perhaps it's that?

Actually, thinking about it, if my original thoughts on the waste gate are true (in that it's open at low revs when the turbo's off-boost), then you ought not to get the ticking sound at idle, either.

I just don't know - I'm really clutching at straws here, I'm afraid...

I'll go for a drive in a bit and see when it does it and if it is related to boost.

Even if it was the fuel pump, in an injected engine, its only function is to maintain a pressure (regulated by the FPR) behind the injectors. The air/fuel mixture is regulated by the ECU by varying the pulses to the injectors, based on inputs from the lambda probes and the MAF. Since a failing fuel pump is more likely to deliver low pressure than high, I'm not sure how that can translate into poor MPG.

I can see a possibility that you have one clogged injector and the ECU is compensating for it by richening the mixture at the other 3, since I'm not sure that it can measure the inputs from the lambda sensors to correlate the value with individual cylinders. Others may know more about this. Have you run some injector cleaner through it? Also, have you looked at the plugs, as suggested by another poster a few days ago? If one is significantly different in appearance from the others, that would tend to lend weight to this theory.

All plugs look to be the same as this one I photograhped.

They look fine but do show signs of it running a little rich.

I've not ran any injector cleaner through it as I wasnt sure that was "the done thing" on a modern car. However, I do run a mixture of BP Ultimate/Optimax/95 RON and if the hype is to be beileved the higher rated fuels sound do some cleaning.

That plug looks just fine, not rich at all. Sorry, missed the response with the pic in it last time. How old are the plugs? They only get changed every 40k miles these days but can benefit from replacement earlier sometimes. Injector cleaner can do no harm - although some makes are more efficient than others apparently.

That pic was one of the plugs I removed recently, now running a complete new set and it made no difference.