In this entry I will compile recommendations, which have to be taken into the account, buying the car with N43/N53 series engine. Of course, part of recommendations are general and are actually for all petrol engines, but I will try to put an accent to those ones, which are characteristic exactly to these, quite specific power units.
I will start the review with the thrilling moment – financial resources are gathered, several vehicles are identified, the inspection is organized. In front of you – first or one of several candidates for purchase.
Vehicle options and other arguments – your choice. In this entry – only things, related to the engine.
1. Turn on the engine. EML (“Check Engine”) indicator lights up on the panel? I would recommend forgetting about this car. Of course, each engine can have slipped up. But, if the owner of the car has not solved it till the moment of car’s inspection or, even worse, he thinks, that “this is not a significant problem” – that really is A PROBLEM. Many think, that the indicator lights in yellow color has only informative meaning and easily continue to drive with lighted up EML indicator. For N43/N53 engines, the EML indicators light up only in emergency cases. For example, damaged NOx system; decreased efficiency of CO catalytic converters (if it’s not total 0) and many other expensive problems (including injectors) will not light up this indicator. In the same time, solving these problems can cost several thousand EUR. EML is lighted up, for example, if there are fundamental problems with maintaining the fuel pressure, the performance of CO catalytic converters is 0, group misfires are in common etc. In any case – EML indicates, that there are serious functional problems. Also, if KOMBI/CID displays other notifications, for example, missed service intervals, not working ABS/DSC system and similar – it doesn’t show, that the car is well maintained;
2. The engine switches off not swiftly, but in first few seconds is reluctant to gain RPM, shivers. This is a typical syndrome if the engine has problems with reaching fuel pressure or leaking injectors. In the first case – there is no engine which to inject, in the second case – in some (several) cylinders is leaked fuel, the amount of it too high (about this – also in the section regarding oil);
3. In idle, the engine works unevenly, RPM is fluctuating or shivering. These engines one typical problem – in case of the cold engine: “leaking” of the injectors. Taking into account, that cleaning can also not help, but new injectors are quite expensive (around EUR 300/piece), more serious diagnostic is recommended. In any case, this is a symptom, which has to be paid attention to. Yes, you could be lucky – the reason could be a defect of some ignition coil, but that would be true luck, not regularity;
4. The defect, the importance of which is difficult to overestimate. As if the not significant problem, which could lead to expenses of 3000 .. 5000 EUR. More precisely – replacement of CO catalytic converters, replacement of Lambda probes, replacement of NOx sensor, also the defect of NOx catalytic converter is possible. What is it? Crankcase ventilation! Damaged crankcase ventilation causes increased oil consumption, which instead causes defects, mentioned before. How to quickly check crankcase ventilation?
- turn on the engine (don’t press the accelerator pedal – so it will be guaranteed, that the engine will work in Homogeneous mixture mode);
- open the oil filling cap.
If in the moment of opening the cap the performance of engine swiftly changes – the idle becomes uneven, the engine shivers: the crankcase ventilation system is damaged, and such engine has to be evaluated very critically. Anyhow serious inspection of the exhaust system performance has to be executed.
If opening the cap, the very strong stench can be felt – obviously, the oil is mixed with fuel. This is possible in two cases:
- injectors are leaking – after switching off the engine, fuel leaks in crankcase;
- the engine piston group has worn out, the fuel in compression cycle (in Homogeneous mode) is pressed in the crankcase.
If strong stench of the fuel can be felt – the purchase of such car has to be re-evaluated very carefully.
Of course, the experienced car user will listen to the “melody” of the engine – aren’t some clinging, loud ticking, grabbing (wear of the shaft, compensators, lubrication problems, chain grabbing respectively) present, but – if the engine has no problems mentioned before, I would recommend continuing with some more diagnostic tests.
The cause – many problems cannot be seen/can not be heard, but can cost very expensive.
Required equipment: INPA (recommended), ISTA D/+. Other diagnostic software could be very low-efficient.
5. Error message inspection with INPA/ISTA. It is highly recommended to use INPA because it contains 3 lists of error messages. Even, if the actual error message list is “cleaned”, the error messages will still be stored in the history list. If also history list is empty – increased attention has to be paid to this obstacle. Such diligent deleting of the error messages is quite, even very suspicious. Good news – for example, the error message 30E9 (regarding the insufficient performance of NOx catalytic converter) cannot be deleted and can be seen immediately (but it doesn’t prevent the hiding of this error message for some period of time – see the notes at the end of the entry)!
To which error messages have to be special attention paid? To all, which elimination can require large capital investments:
- error messages regarding fuel pressure, especially: HPFP;
- error messages regarding the performance of CO catalytic converters;
- error messages regarding defects of NOx system.
Yes, for repair of NOx system there is a solution (NOXEM) – but still, these are expenses. In any case – the solution of NOx system problems is with expected expenses, but it is also a reason to ask for a significant discount.
The error messages relating CO converters can be registered unjustified because the car drives short distances in the city for long period of time, but still – it is worth to pay attention to them. New CO catalytic converters and Lambda probes will cost above 1000 .. 1500 EUR.
Error messages regarding HPFP can be registered because of incorrect fuel low-pressure, but – in worst scenario – you will have to repair/replace the expensive (around 2000 EUR) high-pressure pump – keep this in mind.
Unfortunately, problems with injectors usually are not visible, they are “hiding” behind other error messages and symptoms:
- error messages: misfires, fuel trim etc.;
- symptoms: abnormal performance of the cold engine, increased CO/CH for the warm engine – the car is not able to pass the Technical Inspection (relatively increased also performing in Stratified charge, but TI can be passed), vibrating performance.
Error messages of NOx system:
- 30EA – desulphation of NOx catalytic converter required. This error message can be stored also in Info memory list, and after deleting is not reappearing in the error message list (accordingly – the problem can be “hiding”). Attention – if this error message is present, the normal performance of NOx catalytic converter is NOT guaranteed (it could be damaged);
- 30E9 – unfortunately, the repair offered by the manufacturer is expensive (above 2000 EUR), only less expensive alternative – NOXEM;
- error messages regarding NOx sensor. Attention: only after replacing the NOx sensor, the engine management system will restore the check-up/measurements of performance of NOx catalytic converter. It means, if there are error messages regarding NOx sensor, additional defect/expenses are possible – the NOx catalytic converter can also be damaged.
Note: the average lifetime of NOx catalytic converter is 150’000 km, of course, with the condition, that the NOx sensor is in work order, driving profile – appropriate (regular desulphation is ensured, driving with speed over 110 km/h). Unfortunately, the cases, when the NOx catalytic converter is damaged already for a car with mileage 70 .. 100.00 km, are not rare – the cause is damaged NOx sensor, which is not replaced on time.
6. If the driving session is possible (that would be very recommended), the main criteria, which allows evaluating these engines very quickly – does it performs in Stratified charge. Stratified charge for theses engines is switched on if all systems of the engine work without problems. For this reason – open INPA ../F5/F6 (../F9/F1 also will do), or corresponding live data, using ISTA, and evaluate wide-band Lambda probe indications for both banks. When driving evenly 60 .. 90 km/h (max during 5 .. 10 min), Lambda has to grow to 2.50 .. 3.00. If it doesn’t happen (but no errors are stored), obviously, the engine has some (possibly, hidden, for example, 30EA mentioned, or NOx sensor defects) problems.
If the engine performs in Stratified charge – it is a very good sign. Unfortunately, it doesn’t exclude the possibility of serious problems. For example, the performance of NOx sensor is evaluated during several hundreds of km, it means – if the dishonest seller has performed some tricks, on the inspection moment/selling moment the engine will perform perfectly, but after several hundreds of km you will find out, that NOx catalytic converter is aged/damaged. For this reason, if possible, ask for guarantee time to make sure, that after some several hundreds of km after purchase specific error messages regarding engine performance don’t appear.
Of course, buying such car, full diagnostic of engine electronics would be very recommended – only it will show if the engine has some specific problems.