Ford Focus

Hi Pete, I've got a Ford Focus CMax Diesel and last year in April the car, after 5 years of trouble free running , started to give me problems similar to your car. It would start up fine, I'd pull away and then get to a junction about 100 yards away. When I pressed the accelerator the revs would die to a idle and wouldn't respond to further pressing. Then after up to a half minute it would pick up and all would be well. I put it in for a service with my local garage he changed all the filters, including the fuel pump filter, and it's been fine since....well, that's nearly true as it has just started to occasionally have the same symptoms again, which means that it's going in for another service and fuel pump filter change. Since the car was fine for 5 years and now suddenly develops these symptoms indicates to me that there's been a change in the Diesel fuel somewhere along the line, as it looks like the fuel pump filter clogging and needing either cleaning or renewing.

 

Part of the reason (in my opinion) is that motor manufacturers have been pushed into a situation where they have had to meet increasingly stringent emissions targets, whilst boosting performance at the same time to give us the performance we want. Worse still, they have been forced to do that in a relatively short timeframe (think how long it took from the invention of the car to get innovations such as fuel injection and electronic ignition, compared with the rapid changes in performance and emissions standards in the past 15 or so years) - effectively, they are rushing stuff out that seems to work just fine, but when the computer says no......

The only way they can meet these targets is to use computers to control everything, and those computers rely on sensors all over the place to tell them what is going on. Even on cars with a much lesser performance than yours, the diagnostics are highly specialised, and using the wrong (or generic) code readers only serves to lead you up a blind alley. I am having to take my VAG kit into work tomorrow to try and help a colleague diagnose a problem with his car - purchased from, and has been worked on under warranty by a Vauxhall dealer; in short, they haven't got a clue as their kit is not set up to understand the software of his car.

The other thing to bear in mind is the software (or firmware in fact) for the car is tested to ensure it works before the cars are put into production - - sometimes, the only way that a bug will appear in computer code is when it is in service and meets a given set of parameters that the guy who wrote the software didn't ever dream would occur in a million years. I have designed a software app for my company, and on a number of occasions in use in the beta stages, a user has managed to highlight an issue simply by clicking things in a sequence that I never imagined would have been possible - - and the vast majority of any computer code is exactly the same, that is why they have Beta versions, which are essentially live tests.

Yours will almost certainly be a sensor or a software issue, but it might well take some tracking down.

EDIT - the first one that shot into my mind was a crank position sensor, simply because I had similar symptoms when I had a knackered one once, but as longk rightly points out, there are just too many things to go guessing.

 

I've done a bit of research due to my original line of thought, Sheal, about there being clogging of the fuel pump filter and found this on the Ford Service Centre Forum:

"I just replaced the fuel pump on my son's 2001 Ford Focus, 44,000 miles. I've researched the problem with these pumps and from viewing the pump I pulled out of his Focus, its clear the problem is the contamination from fuels clogging up the pickup strainers to the pump, there for straining the pump and causing it to fail. The relay usually kicks it off, but over time the heat and strain put on the pump will cause it to fail. There are two strainers on the pump, the sock is clearly the item clogging. Wether this is from bad fuels or the filtering property of the sock is unknown.
I went to auto dismanterler and purchased a used pump for $59. with 90 day warranty. It too had a severely contaminated pickup sock on it. I cleaned it and installed the pump. The Vehicle works great now and my son has returned my Ford explorer to me...in one piece.
The pump on the Ford Focus is the same basic pump installed on 80% of ALL vehicles onthe road. Being a ASE technician, its it only my opinon that the problem might be with the cheap fuels being used, or the pickup sock on the pump. Majority of the fuel tanks I've pulled over the years, there is no contamination and these vehicles had 100,000+ miles on them, except for this Focus. Good luck!!"