Lean Burn Stumble 1.8 petrol 2007

[David J A Horne]

I bought a new Focus 1.8 petrol in March of this year and it soon became obvious that it was occasionally misfiring at between 2500-2750rpm.
Summary of performance:
Car accelerates very smoothly between 2000-3000rpm.
Car is very smooth when cruising at 70mph.
Problem occurs when I change from doing one to the other, especially when changing from cruising to accelerating when it will initially misfire at between 2500-2750rpm. If I continue to speed up and slow down the fault will clear itself which would suggest to me that whilst the engine management system is doing its job it's taking too long to do it. This car has been in and out of my local dealer's workshop several times and they have found nothing wrong with it and Ford have refused to come down to look at it. The general consensus now is that it is lean burn stumble which I will have to learn to live with. They have taken me out in another 1.8 petrol which although also running rough was behaving somewhat differently to mine. I supose they were just trying to prove that all 1.8 petrols run rough.

[GapBoyPCS]

Welcome.

Unfortunately, this site is geared towards the North American Focus. As a result, we don't have the 1.8L petrol here. However, since it's a Duratec, maybe some folks here can extrapolate their experiences from a 2.0L to your engine.

If you do find your dealership isn't able to resolve the issue, you may also resort to taking it to another dealership for diagnosis. Also, you should document each time this happens and actually write to your local Ford head office and CC the dealership principal and service manager. Your manual may have the different ways you can obtain resolution to issues with your vehicle. Also, if you're part of an automobile club or association, see whether they have recommended shops that perform diagnostics.

But, be sure to pursue whatever is shown in your owner's manual first.