Engine malfunction - service now

[Another Richard]

Focus Titanium 2.0 Tdci, 2014, 105k miles

Bought this car back in February this year. I hadn't had it a week when the car went into limp mode and I got the above message on the dash. No other warning lights. I had been experimenting with the cruise control on an A-road at 50-60 mph, and the fault occurred when the car was gently accelerating under the CC in either 5th or 6th gear. Pulled into a layby, stopped the engine, restarted and all was well. No warnings, driving as normal. I took it back to the dealer who found no fault codes, but replaced the fuel filter as a precaution.

Then we had lockdown, and the car has had little use, perhaps only twice a week. It has all been local journeys, fairly short distances, lowish speeds, and the car has been faultless. Last Friday I did a journey of 400 miles, mainly A-roads, and the fault returned several times. It first happened when I had been going about 50 miles, driving briskly but not caning it, and then recurred probably 10-12 times over the rest of the journey. Stopping and starting again cured it in most cases, although sometimes I had to leave it 5 minutes before it would start again without limp mode/engine fault light. The warning lights were a bit random - most times it lit the Stability Control warning (yellow car symbol with skiddy tracks) but not always. A few times the engine light (yellow outline of engine) came on. Sometimes the lights stayed on, sometimes they went off of their own accord. Sometimes they came back on again, without the malfunction message. The engine light was on when I got home and was still there the next morning, but disappeared after I filled the car with diesel (5 minute stop). Common factors seem to be a) engine is thoroughly warm, and b) light acceleration in high gear or heavy acceleration in lower gear.

I know the first thing is to read any fault codes, but I have no way of reading them at the moment. (Suggestions for OBD reader welcome.) Until then, any ideas? It sort of looks like it might be related to fuel starvation, but it was warm weather (no waxing) and a recent fuel filter. Also, I was using supreme diesel on the long journey. Another thing which might be related is that fuel consumption is not as good as I expected. I'm getting around 36 mpg (UK) local driving and 47 on the long journey, both measured brim to brim, not the mpg display. My old 2006 Mondeo (2.0 Tdci also, and bigger, heavier car) would have given me 42 and 50+ in the same circumstances. Honest John Real MPG suggests an average of 46 mpg for the engine, so it's well below that. It also feels no more powerful than the Mondeo, despite being smaller and lighter, and having 10 bhp more. Am I being realistic?

Car starts and runs fine otherwise, and I am delighted with it. If I can just solve this issue, it will be my perfect motor.

Sorry for the long post, but I'd prefer that to drip-feeding information. Any help or suggestions very welcome. Thanks all.

[WireyWhenWet]

Few things to check, have you got an aftermarket air filter in?

That engine is sensitive to airflow, so if so it's probably one of two things; it either doesn't like the current flow (Mine does this, I have a removable end bung and lid off and it's fine, but with any of those two on it doesn't like it, so either a LOT more air or normal, nothing between for me!)

Or failing that, check/clean/change the MAF sensor just out of the airbox. Quick cheap and easy swap for all.

Finally, you did the fuel filter - Might be worth checking the o ring seal as they have to be absolutely perfect, a tiny mis fit causes air to seep in and can cause fuelling issues such as described, including requiring multiple goes at starting the car to get it to prime and fire up.

[Another Richard]

Sam, thanks for this. I haven't done anything more than check the oil since I have had it, so I *assume* it has a standard air filter, but I will check. And the selling dealer changed the fuel filter (or said he did, anyway) so I had no input there either. I'm happy to check most things, but I have read on here that the fuel filter is a job best left to a garage, and I can't seem to find any kind of workshop manual. Same with the MAF sensor - I'd be working in the dark a bit. I am happier with older engines!

Will have a look at all of those. Many thanks. Car starts instantly every time, so I doubt an air leak.

[WireyWhenWet]

Not a worry at all, I've been there and Ive had hell with mine overally chasing all sorts due to the dealer misfuelling mine just before collection... In all honesty the MAF is probably easier than a bulb swap really for the most part, especially if you're checking the filter out as well- Sounds like it's probably original and could even just be clogged up to chuff which wont help!

The fuel filter is a tad more intensive but is a very very easy one to get slightly wrong enough for it to make a difference such as this, better left to someone a little more in the know really. The haynes manual for your focus should have the MAF info in there I think, but if not take a look at your air box, and the pipe that goes to your engine from it, near the box there will be something screwed in, that's the sensor- it's a matter of just unclipping the cable from it and taking the pip off from the box after undoing the jubilee clamp that connects it up to the main air pipe of the engine.

[Another Richard]

Unfortunately, the Haynes manual for my model is the US spec and doesn't cover the diesels, so I didn't bother getting it. I've changed fuel filters on other cars before, so I'm not a novice, but reading from somewhere in this forum that it was better left to a dealer made me think twice. If I knew where it was I would give it a go, or at least assess whether it was within my abilities.

The air filter is a Mann C16 134/1, and looks almost brand new. Worth replacing with a genuine Ford article? (I've done a lot with Land Rovers, and there are instances there where paying the extra for a genuine part is well worth the extra money.) The MAF is the little device in the elbow just downstream of the air filter box? Impossible to see its condition without removing, but the pipework around is clean and dry. There's no jubilee clip - it seems to unscrew from the side of the AF box, and the stub is just a push fit into the intake pipe. I'll have a look at prices - if it's not too much I might replace it just to eliminate. [Edit: ECP are selling them at nearly £100. May try that later.]

Thanks again, appreciate the help.

[WireyWhenWet]

5 hours ago, Another Richard said:

The air filter is a Mann C16 134/1, and looks almost brand new. Worth replacing with a genuine Ford article?

 

The MAF is the little device in the elbow just downstream of the air filter box?

Its probably all good of it looks to be a newer element to be honest, so that seems to be a good thing in one regard.

 

For the MAF, yep that would be it - Id be inclined to experiment with cleaning or trying a second hand one as a cheap option before going all out with new to be honest, £100 seems quite steep in my opinion, is that after a discount as well or before applying codes?

[Another Richard]

That's the price off the page. Not aware of any discounts or codes running at the moment, and I haven't done an extensive search. Just wanted an indication. What's the best thing to clean with - cotton bud and meths?