OT. Diesel misfire on a light throttle

[Ratty43]

Evening all,

Off topic as its the 2.0 Duratorq diesel in my x-type but since the same (ish) engine is in the Freelander 2 I'm hoping I'll be forgiven and someone will be able to shed some light.

On a very light throttle at about 1750-2000 rpm the engine feels like it is missing, its very violent, to the point that I either let off the throttle completely or accelerate; originally this only occurred at 50mph in fifth gear on a particular stretch of road which is very slightly down hill. However recently its become more common and I can induce it by using a light throttle in any gear. Originally I thought it might be the EGR as the engine was also smoking a bit so this was replaced with a genuine Ford EGR which got rid of the smoke but not the misfire (or whatever it is in a diesel). 

As a bit of background the car runs brilliantly, despite having covered 186k miles with no smoke when accelerating and pulls well with good fuel efficiency. I've checked all of the hoses and there is no sign of any splits, I've also plugged it into a code reader which showed no faults nor did the live data look odd, I had wondered if there was an issue with the throttle itself but this increased smoothly without any jolts etc.

Any help would be gratefully received.

Thanks in advance!

Barney

[Bull Bar Cowboy]

Welcome to the club ! …………………..

 

This engine has suffered this issue in pretty much all applications, however, some are worse than others. With my Volvo V70 it is more of an irritant than an issue ………… at about 1800rpm under a particular engine load at a particular throttle setting you get this symptom of uneven running ……. Some describe it as misfire, others describe it as hesitation or stutter ………… to me it is like a misfire but it obviously isn’t, as the ECU would flag it in an instant.

Check out the forums for the Mondeo, S-max, and focus ………… there is load written about it. Also look at the Peugeot 208 forums for similar info.

Some of the Ford users claim to have cured it by blanking the EGR ……….. this you can safely do on a Ford and maybe the Peugeot’s, however, on my V70 application it is not an option as it will bring on the engine management light (MIL) ……… this is because Volvo look at EGR pressure as a management function.

 

Changing the EGR was a good plan as these are known to fail on this engine at between 100 -150k – if yours is fitted as most others are, then it is a pretty unpleasant job to change due to the hidden allen bolt below the valve at the back of the engine, Most grease monkeys just snap off the lug and remove it afterwards ……… it is essential to clean all the pipework right through and past the EGR cooler ……………another known issue is the throttle body sticking (the throttle is electronic) ………. Just take it off and give it a good clean.

Generally a good engine ……………. mine is pushing 140k with no real issues ……………..

If you find a 100% solution to the problem, I guess you could end up very rich ! …………….. for me it is an irritant, it only happens very rarely ……… you just need the critical load and the critical throttle opening ……….. jumping on the loud peddle clears it in an instant.

Edited May 8, 2017 by Bull Bar Cowboy

[Ratty43]

Thanks for your input. Luckily the egr on the x-type is at the front so wasn't too bad a job. I cleaned out the pipes and the manifold at the same time although they were all reasonably clean. 

The throttle body is a good shout, I'll give it a go, thank you. I'll update as to the effect. 

Agreed it's a great engine despite the current issue. 

Cheers,

Barney 

[ThreePointFive]

I own an XF and have seen/read/heard of a similar sounding problem but that is a totally different platform and engine... however, they have been known to develop hairline cracks in the plastic inlet manifolds (again, I don't know about the 2.0) and create symptoms exactly as you describe. They are also very difficult to locate.

The sensation that best described it for me was as though someone had put a restriction (like a hand) over the air intake or like doing 20mph in 6th gear, before clearing completely as if it never happened. It was quite violent. On the car I know of, it had no fault codes and was otherwise perfect except this intermittent issue, it took a number of visits to the garage to resolve so it was clearly not obvious.

Don't know if any of that will help but worth a shot. I also own an X Type (though a petrol V6) and they are great cars.

Edited May 9, 2017 by ThreePointFive

[Ratty43]

Thanks for the input, I was amazed that the inlet was plastic with a turbo on the other end. It's a fair point as it would be no different to a pin hole in the hoses. 

I agree that they are great cars, I had a 5.3 X-JS and still have a low mileage XJ40. To be honest I only bought it as I needed something more efficient than the Defender and was surprised at how good it is. The Mondeo based comments are a bit unfair although it's not a patch on older jags for ride quality, uses half the fuel though!

I have thought about using the XJ40 for work but I'm a Quantity Surveyor so spend my days on building sites and I don't think 80's steel and cement would mix!

As it happens it's gone from pretty constant to not present for the last couple of days. This rather makes me think that it's an electrical fault like a corroded connection but I would have thought this would have shown up on diagnostics.

[Norton18]

One of the injectors spray pattern is wrong due to age or carp build up, injector probably dribbling at idle. Best thing to do is change the injectors for a recon / new set or at least get them tested. I presume you have checked fuel pump deliver pressure, changed fuel filter and checked tank return clear? Check they do not require mapping to ECU if so get a garage to do it.