XR4x4i (1990, 2.9i V6)

Replace the air filter with a clean one or put the old one back in. Some cars don't like the unrestricted flow or so I'm given to believe.

A perfectly clean air filter shouldn't cause any kind of restriction, so that shouldn't be the problem.

I would try putting another gallon of fresh petrol in. If that improves things, then it's likely the old petrol is causing the problems, and I would just fill the tank up with fresh petrol, which should dilute the old petrol enough to make the car run reasonably well.

Failing that, you're looking at an injection (or possibly ignition) fault.

Sounds like 'fuel starvation' and as petrol 'goes off' after about 6 months it may be that the fuel system is clogged with the deposits that petrol leaves behind as it degrades. Try fitting a new fuel filter and also try to clean the fuel system using an additive for fuel injection systems or perhaps a dose of redex in the tank.

Hope this helps

Radar

In news:_ZtSd.149302$ snipped-for-privacy@fe3.news.blueyonder.co.uk, radar decided to enlighten our sheltered souls with a rant as follows

With a 4x4 Sierra you're probably looking at a new ignition module. They're forever packing in, but are reasonably easy to get, being shared with the Granada 2.9.

The fuel pump fuse (main fuse box) can sometimes go intermittent if some water has got into the fusebox. Listen very carefully when you select position 2 on the ignition. You should hear the fuel pump run for a second. If not then suspect the fuse or possibly the emergency collision disconnect switch in the spare wheel well.

It may be that the air flow sensor or throttle sensor has got dirty too. Disconnect each and see how it idles and runs. It should go into limited operation mode and give you some control (but not a lot).

Mike

(nice weather for XR4x4s)