Fiat 500L 1.6 Multijet

Diesel with Bosch management.

Introduced in 2007, Fiat’s 500 has been a huge hit and there have been a number of different versions based on the original model. One of these is the 500L, development of which started in 2010 to provide a more spacious MPV on a compact platform. It shares many similarities with the Jeep Renegade.

The newcomer was intended to replace the Fiat Idea and was designed around the Fiat/gm ‘Small Platform’. It emerged at the Geneva Motor Show in 2012, featuring a cab forward design, in which the emphasis is on interior space. A major plus point is the so-called Magic Cargo Space, incorporating a triplelevel load compartment floor, rear seats that slide, fold and tumble, and a front passenger seat that folds flat.

A variety of engines have been offered, including Fiat’s twin-cylinder Twin Air petrol units, a four-cylinder petrol engine and Multijet II common-rail diesel, in four-cylinder 1.3 and 1.6-litre forms. Further engine options arrived in 2014.

Having made their debut in 2003, Fiat’s Multijet diesel engines employ five rapid injections of fuel per cycle, introduced under very high pressure, enabling quiet, fuel-efficient combustion. The Multijet II units, first introduced in 2009, are even more advanced and feature new injectors delivering eight injections per cycle, plus higher fuel delivery pressure, resulting in even more precise operation.

Our car here was registered in June 2013 with the engine (code 199B5.000) controlled by a Bosch management system. Our guide to this model’s engine and its system is Edward Haggar.

Preparation

For reliable long-term operation, it is essential that engine maintenance is carried out regularly. When installing a new air filter element, always ensure that the replacement element is of good quality, because inferior types tend to break up, resulting in debris that affects the performance of the air mass sensor.

Note that whenever the diesel filter is renewed, an in-line pump should be used to aid the bleeding of air from the system. Failure to do this will result in excessive engine cranking, which can damage the starter motor. There is also a risk of internal damage within the fuel system, caused by the lack of diesel fuel which normally lubricates the system internally.

These engines are prone to suffering from water pump failure, which may result in the cam/water pump drivebelt jumping, causing catastrophic failure of the engine. Very often the cambelt is renewed but the old water pump is left alone.

Fault 1:

THROTTLE FLAP PROBLEMS

Symptoms of our first fault include a lack of power/poor throttle response, and the engine may crank for an extended time but refuse to start. Stored codes may relate to too much or too little air mass transfer through the engine. Equally it is possible that no codes have been registered, in which case live data should be consulted, looking at air mass aspects. The precise numbers aren’t as important as seeing a figure to indicate movement of air mass through the engine.

If a lack of air flow is confirmed, detach the intake trunking and unbolt the throttle flap assembly for close inspection. Once the assembly is removed from the engine, take care to ensure that the flap is not rotated violently nor through a large angle; minimal movement is best.

The throttle flap tends to stick in the closed position, resulting in the above symptoms. This can be addressed by the use of a carburettor/throttle cleaner fluid (which should not be too aggressive in nature, to avoid component damage) applied carefully to and around the flap by means of a cotton wool bud or similar.

Some test equipment incorporates an ‘actuator test’ function, in this instance enabling checks to be carried out to confirm that the flap fully opens and closes as designed – very useful after cleaning operations have been undertaken. Once reassembly has been carried out, re-learning operations are required, and this job can be tackled by most diagnostic test equipment.

In many cases it will immediately be noticeable how much more responsive the vehicle has become, since the engine will once again be operating in line with the original factory settings. Over time the ECU will adjust to a gradually deteriorating situation in which the throttle flap is starting to stick, etc, so the car will still run, but below optimum performance levels.

Fault 2:

DIESEL PARTICULATE FILTER PROBLEMS

When our next fault arises, the driver may notice a burning smell. Initially the car will still be driveable, but eventually the oil warning lamp will illuminate and, if you continue to drive the car, the ECU will shut down the engine completely.

What is happening is that the DPF keeps regenerating itself and a sensor within the engine oil senses this, which reduces the effectiveness of the oil. The motor is closed down to prevent damage.

A diagnostic check may reveal fault codes relating to DPF pressure. Depending on the test machine, it should be possible to view live data, and a pressure reading across the DPF of about 0.2 Bar should be seen; readings any higher than this indicates a blockage within the filter.

The root cause of this is likely to lie within the ECU software. The situation is most likely to arise in cars that have not seen a dealership workshop in a long time, since Fiat issued ECU software updates to dealers to cope with this problem.

The ECU can be reprogrammed – or the car can be returned to Fiat for a new ECU – although Fiat’s positive response to a car that has not been dealer-maintained cannot be guaranteed.

We recommend sending off the car’s ECU to have the unit remanufactured. On its return, the unit can be plugged straight back into the vehicle. Conversely, if a new ECU is fitted, it will need to be programmed by Fiat, an independent diagnostic specialist or a locksmith.

Alas, this is not the end of potentially expensive problems, for the DPF also needs to be removed from the vehicle and checked. It is highly likely that

damage will have occurred within the unit, necessitating a replacement at a cost of around £800 for the DPF alone.

Fault 3:

FAILING FUEL INJECTORS

Symptoms of this problem are a vehicle that is reluctant to start, although in the early stages, the car’s driveability may seem fine. However, the manner in which the car drives will deteriorate as the problem – due to injector malfunctions – becomes more serious.

Diagnostic interrogation may reveal fault codes relating to the injector circuit or fuel flow, although not necessarily excessive fuel flow, and the codes won’t always be cylinder-specific.

Live data can be used to observe and compare the efficiency of all four injectors. It may be evident that one or more of the injectors is delivering significantly more fuel than the rest. A diesel leak-off test can also be carried out to ascertain how much leak-off is being drawn off at the injectors. Generally, a faulty injector leaks off at about twice the rate of a healthy one. When installing new or reconditioned

injectors, always renew their copper seals at the same time. It is good practice to renew all four injectors at the same time, even though they cost around £200 each.

New or old injectors will need to be reprogrammed on installation, using the identification number shown at the top of each injector. It is possible that the ECU may lose the original codes. Although the engine will run if reprogramming is not carried out, this procedure is advisable to obtain optimum performance and fuel economy. It is also wise to renew the fuel filter in conjunction with the injectors. If a faulty injector is identified, the fuel filter housing should be closely examined for signs of debris/filings, which can clog the filter and damage the injectors.

Fault 4:

EGR VALVE MALFUNCTIONS

In the early stages of this problem, the management system warning lamp may illuminate, but at first there will be no difficulties in terms of driveability. A diagnostic interrogation may bring up fault codes relating to Egr/flow, due to sooting-up of the EGR valve.

If the problem hasn’t reached a serious stage, clearing the fault codes and using a good-quality diesel fuel additive may do the trick. However, if the fault is left to its own devices, the valve will continue to soot up and the engine will lose power or may even become impossible to rev at all.

Unfortunately, the valve’s buried location does not help when it comes to accessing and cleaning it, being tucked away below the exhaust manifold. The valve incorporates a built-in cooler to help reduce emissions. However, the cooler adds to the cost of renewing – between £300-400. Fortunately, it’s not a dealer-only component.

In our experience, if a valve is cleaned, in 90% of cases it will soon need to be renewed anyway. Therefore, in view of its inaccessibility, renew the unit regardless.

When a new valve is installed, it will be necessary for adaptions to be relearned, in order to restore the manufacturer’s original settings. Live data can be used to operate the valve – which is activated electronically rather than, for example, operated by vacuum – to ensure that it fully opens and closes as designed.