Usually If I lift off the throttle, in gear whilst going down hill or slowing down my mpg rises rapidly beyond 100mpg until I get --- which I asume means that the forward motion of the car is keeping the engine running alone and no fuel at all is being injected into the engine.

Recently however when I lift off the throttle the best I can get is around 140mpg. This has had a big impact on average consumption I have lost around 5-7 mpg overall.

I have not had the car on diagonstics recently but that will be my next step.

The only change I have made is to use cheap supermarket petrol rather than my usual V-Power.

Can anyone help? Or has anyone experienced the same thing?

sounds pretty normal mine goes up to 160mpg when i take my foot off the pedal beford going to ---mpg but the vectra i have as a hire car goes to 999.99mpg

No, you miss understand me, the car no longer goes to ---, the highest it now goes is around 140mpg

I believe it maybe the overrun cut off valve if that helps anyone?

On the overrun the car should be using no fuel at all, and all fuel is passed back to the fuel tank until you apply throttle. You maybe correct on the valve front though, it sounds feasible that something is sticking preventing fuel flow back to the tank.

I'd say the OP's problem is with the over-run cut-off, or the return.

Incidentally, mine's a diesel, and will go as high as 700mpg before going to ---.- .

Edited 21 July, 200817 yr by KenONeill

I had that problem once after proper bootin it, all i did was get some spead on the empty motorway then leavin it in gear, turn the ignition off remove the key then jus put ignition back on so the car bumps its self

never had it happen again.

You have got to be insane with a suicide wish to do that.

Y? It worked lol

there was no one around and it was still light and on a straight, I didnt think it was that bad,

What about the steering lock?...lol

What about the steering lock?...lol

That was exactly what I thought. Also no servo assistance for the brakes so if the steering locks would mean slower stopping time. Not something I would ever try or recommend :eek:

as far as time goes it took 2-3 seconds to do it and when you can see more than a mile down the road it is nothing..............

But I dont care really as it sorted the problem.

try it at ur own risk but I was confident that noting was gonna happen

That was exactly what I thought. Also no servo assistance for the brakes so if the steering locks would mean slower stopping time. Not something I would ever try or recommend :eek:

I'd not try it either, but you should have enough vacumn in the servo for one stop even with the engine off.

TY Ken. you can stop when engine its off however I made sure that I didnt need to use my breaks or need to turn the steering wheel. I am a very onfident driver and dont take risks (IMO) For most drivers I wouldnt try it but if you switched on and vigilant there is no reason not to do it as I didnt know what else to do so I gave it a go and it worked. so I am happy.

If you get it sorted MART let us know how

Ok mate; I was saying that I wouldn't try it (cos I'd not want to risk the steering lock engaging), but you do have enough vacumn to stop as long as you stop and don't muck about!

lol I know from just rolin the ar down the drive a bit. you gotta push VVV hard to get it to stop lol.

must appologise if I came across a bit strong, not keen on bein....... critiseised lol.

hope the prob gets sorted,

find a deserted car park and try it there 7am on a sunday morning.

I'd say the OP's problem is with the over-run cut-off, or the return.

Incidentally, mine's a diesel, and will go as high as 700mpg before going to ---.- .

Same with mine also.