Stage two of the repair works
Connection with SINE restored. The customer got lucky – even the syren module is still working!
The Integration level of the car increased to the end of the Year 2016, all modules upgraded correctly.
LPFP pump and its connecting pipes replaced.
Injectors of cylinders No.1 and No.6 replaced, encoded.
I am performing the readaptation of the engine.
Here, LPFP data after replacement of the pump:
As we see, the voltage, supplied to the pump, has dropped from 8.1 .. 8.9V to 6.2V; the voltage – reduced. So – the new pump uses 30 .. 50% less electrical power to perform the same mechanical work!
But, the most important – the electrical power used by the pump, is very stable! No shivering!
Interesting nuance: after installing a new pump, DME/EKP needed 10+ minutes to re-adapt the LPFP adaptation maps. Initially, the pressure of the pump was increased: around 6 Bar; the error message regarding increased LP contour pressure was recorded in the DME error message memory for several times. One more confirmation that the old pump was bad at his job – its pressure was lowered.
Injectors data – correct, the engine runs smoothly, evenly, uses a Stratified charge.
At this moment we have finished with solving problems of previous “repairs”:
- problems with SINE fixed;
- problems with DME software fixed;
- problems with LPFP pressure fixed;
- two problematic injectors (which as if were replaced, but turned out to be damaged and of very old (02) release) – replaced.
- Integration level of the car – upgraded;
- NOXEM installed, Stratified charge restored;
- the engine re-adapted, the performance of injectors, and other systems evaluated.
Unfortunately, the story is not over yet.
Suddenly the icon of the “half-working” engine lights up in KOMBI; in the DME error message memory, the error message 29F2 appears, and HPFP is turned off.
Continuous analysis of HPFP performance confirmed the worst suspicions: sometimes, some valve of the pump tends to stuck. Most probably, it’s the hydraulic pressure valve. HPFP is able to maintain the correct pressure for an unlimited time even in case of high flowrate, but suddenly its power drops so much that even in idle it is not able to maintain the required pressure. During the time of several seconds, the pressure of HP contour drops to 50 .. 100 Bar; an appropriate error message is recorded. After recording this error message, DME switches the pump in “safe” mode, and then it is not able to maintain even 30 .. 40 Bar.
At the same time – all cylinders continue to work, fuel mixture – correct enough. Conclusion: HP sensor indicates correct pressure; no injector is leaking.
Obviously, finally, we have “reached” the cause of all fuel pressure problems: HPFP. Accordingly: replacement of LP and HP sensors, also the unsuccessful “renovation” of LPFF, were done unnecessarily (it was also confirmed by the fact that after these “repairs” no improvements were observed).
It is easy to calculate that the customer paid some EUR 600 unnecessarily for the “repair” of previously mentioned hubs:
- EUR 50 + EUR 50 – sensors;
- “restoration” of the pump – EUR 50;
- “repair works” for at least three times – EUR 150;
- new OEM pump – EUR 250;
- installation of the pump – EUR 50.
Of course, the costs are approximate, but I believe they are close to the truth.
Next stage: replacement of HPFP.
At the end of the entry, a short reflection – what could happen to the HPFP? The mileage of the car is only around 220’000km, it is plausible – the car was bought in our county, all previous owners are known.
Here we have to take into account the following nuance: the car was used for short drives – daily driving to the work and from work: short distances, basically in the city. Accordingly: its average speed was low.
At this moment I will mention two cars for comparison.
- The first one: low average speed, for example, 15km/h. This is a typical average speed for the car, which drives short distances in the city;
At the mileage of 200’000km, this car has “driven” 14’7000 motor hours.
- The second one: the car, which basically drives on the German motorway. The average speed of this car could be 60km/h or even more. At the mileage of 200’000km, its engine has worked 4x fewer motor hours: only 3670.
Looking at these numbers, we can make another conclusion too: the number of motor hours of the first car corresponds to the wear of the second car by mileage of 800’000 (!)km.
Of course, the bearings, the axes of the existing car, have performed fewer turnovers, but the engine (and HPFP also) has worked an impressive number of cycles.
The second nuance: the car was used in a relatively small city. The possibility that sometimes it was refueled in a small fuel station with rare use – very plausible. Accordingly: refueling in such fuel stations the risk to “fill” the fuel tank also with some debris, impurities, etc., which can get in HPFP, and its valve is very high.
Are these assumptions the cause of the HPFP defect? I’ll tell you in advance – no! The situation is even more interesting. Read Part 4!