Ford Mondeo Tdci Injectors/ Fuel system

Views 6 Likes Comments Comment
Like if this guide is helpful

Ford Mondeo TDCI Injectors faults / fuel system.

Ford Injectors, in particular Mondeos, are notable for their unreliability. These failures are not necessarliy associated with vehicles that have covered huge mileages as there have been a fair few reports of injectors failing on these cars at 40k+.  
 The fact that the injectors on the Ford Mondeo TDCI engine are precision items, under high pressure, (like many modern diesels) they fail with astonishing regularity. It wouldn't be so bad if the injector(s) were an 'easy' repair and inexpensive, but unfortunately the opposite is true. You can easily pay upwards of a £1000 for four injectors at a main dealer and around £600 upwards at a diesel specialist. On this model the injectors are supplied by Delphi and once fitted will need coding to the ecu of the vehicle. The reason for this is that no two injectors are exactly the same and have minute differences in tolerances etc. Coding of these injectors can be carried out by any Ford dealership or a diesel specialist with the right equipment and at home if you have the software on your laptop enabling you to read codes, any faults stored in the ecu, and programming injectors. F-Super diagnostic equipment seems to be a favourite with DIY mechanics, available off eBay for a reasonable sum. The codes are almost always stamped to the body of the new injector. Injectors unfortunately are not cheap but you can grab a re-furbished one online for around £100+. Note of warning, never use second hand injectors from a car that has been scrapped, the reliability of these injectors absolutely cannot be guaranteed and you could be left with the same problem in no time at all.
        I have seen injector replacements done at independent garages where the injector is fitted but the same injector oil seal, that rubber seal that goes around the injector on top of the cover, being used again, and also the same union fuel pipe being used again. It is good practice to replace all of these parts to be sure of hassle free motoring after the repair is done.  
        Common symptoms of an injector(s) failure will be the vehicle will lose power under hard/moderate acceleration causing the glow plug light to illuminate and the car basically going into something called 'limp mode', which means reduced speed and power, in order to protect itself, on some occasions the engine can stall completely with the engine management light on. Other symptoms are bad starting with alot of smoke noticeable, and rough idling. The car owner may also hear a knocking and tappeting sound coming from the engine, this is one or more injectors failing, leaking back to much fuel.
        Recoding injectors in such an event were the code(s) have been 'lost' is not a repair. It is temporary. You are only 'fooling' the ecu into thinking a new injector has been fitted and sure enough the injector will demonstrate (in time at all) that is indeed faulty and requires a new one.
        One last word of warning. When these injectors fail the ecu throws up some rather ambigious codes that simply indicate that there is a fault with the fuel system, that generally could be anything. P0121 and P0251 being the most common of these.
 In some cases this could be just a fuel filter partially or wholly blocked preventing a decent amount of fuel to reach the fuel pump and cause hesitation and in some cases 'limp mode'.
        The fuel filter is the most overlooked, and cheapest option in these cases. So always try changing your fuel filter, particularly if it has done 10k plus on the same filter.
        Inlet metering valves which are attached to the fuel pump itself are sometimes blamed for these sorts of issues, but generally they are a pretty reliable component but of course can fail, again pretty inexpensive, but fairly difficult to access without removal of a few components at the front of the engine.
        On these vehicles, if you suspect the injectors, always check the fuel pump first. These do fail and when they do it can be catastrophic to the car itself and to you financially. I have heard of a fair few scenarios where the injectors have been replaced at great cost of time and treasure only to discover the car still has a fault. The best way to check for fuel pump failure for the DIY mechanic on these cars is to remove the fuel filter and empty its contents of diesel into a glass jar. Allow to settle and if you can see flakes of black metal swarf settling at the bottom, and in particular if these particles move and react even slightly to a magnet underneath the glass then you have a serious problem. What has happened here is that the fuel pump is failing inside and breaking up, contaminating the fuel with metal fragments which are sent all around the fuel system, damaging the injectors, contaminating fuel lines and pipes and the fuel rail. This is a common problem with TDCI engines and some report it only happens on the earlier TDCI engines, not true, reports of this happening on 05-07 vehicles have been numerous.  No amount of new injectors will ever work if this is your problem as the new injectors will become damaged by the contaminated fuel. The repair is very difficult and time consuming and bills of £2000+ to clean fuel lines, replace all four injectors and a new fuel pump is very probable. You can of course do this at home if you are a competent DIYer but the fuel pump replacement does require a very competent mechanic as these are fitted to the timing chain of the vehicle and are hard to remove and fit. Dependant on how old your car is, in some cases this can mean a write off as the work is cost inhibited.
       The fuel pressure rail is virtually impossible to diagnose without diagnostic equipment. The pressure in a rail before start up should be anywhere between 4-9 bar rising to 250-300 bar on idle and rising further on acceleration. Fuel rails can fail but you must see if the pressure is ok with diagnostic equipment, on many occasions the poor pressure in a fuel rail is caused by something else.
       Modern diesels are complicated and require good servicing but sometimes no matter how diligent a car owner may be, you can't always avoid common faults like these mentioned above. Generally the TDCI engine is good, but with expensive common problems such as fuel pumps and injectors it can be an owners nightmare.

Jonathan Leaker
Have something to share, create your own guide... Write a guide
Explore more guides