Redex etc in Direct Injection Engines

[ratty6464]

Over the last few months, fuel economy in my Z4 had reduced substantially. for the last couple of years, i've always averaged between 25-30 mpg depending on the sort of driving, and it rarely if ever dropped below 20mpg, even on a hoon.

Now it's averaging just over 20mpg. The car is now about 3.5years old, 38K miles, was serviced a couple of months ago, oils and fluids are spot on etc, tyre pressures ok. Can't see a real reason for it.

Has anyone used Redex etc on a direct injection engines? is it safe to do so? does it make much difference? may run a couple of bottles through a few tanks to clear out the injectors etc. or is it a no no?

[trickywoo]

Are you sure the brakes aren't binding / hand brake sticking?

Could also be a failed O2 sensor.

[Monty Python]

If you've got deposits on the injectors, then none of the additives will help - they're just higher doses of the detergents found in normal petrol. They may work, but you need to use them before the deposits start to appear.

If partly blocked injectors are the problem, they need to be removed and cleaned in an ultrasound bath or replaced.

However, I doubt that's the problem as it the deposits wouldn't suddenly appear, they build up slowly over time so you'd see a gradual drop off in fuel consumption rather than a sudden one. Sounds to me more like a bad sensor somewhere.

You could always try an Italian tune-up