No matter how much I talk that the piezo injectors CAN NOT be cleaned, there still are people, who have “cleaned” them, and… And then different problems start: vibration, misfires, shivering, Check engine in the instrument panel.
Precisely this is today’s story. N53 series engine. Injectors have served 30.000 km, and then the owner decided to clean them as prophylaxis. He took them out and gave them to the company, known in the region (France) as ar specialist in cleaning and repairing the injectors. Directly after this procedure, the vehicle owner asked me to perform the diagnostics because the engine suddenly has started to vibrate and shiver.
Here, the live data, which were sent to me:
1-st bank: incorrect Lambda value (it is evident that at least one injector is leaking); in the 2-nd bank – Offset, LTFT has reached max value. The injectors of the 1-st bank may have leaked in the recent past.
As we see, Lambda of the 1-st bank – still reduced; mechanical efficiency of cylinder No.6 (by placement) – increased. Obviously, the injector of the 6-cylinder leaks; started leaking quite recently because DME has not yet resolved this issue.
After repeated restart, the engine switches to Homogeneous mode, but the data of the NOx sensor:
Total Lambda is incorrect – obviously, the trim of the wideband probes is incorrect (due to irregular leaking of injectors); Offset value – increased. It, instead, means that some of the injectors are quite strongly leaking in the closed position (Overrun mode).
Here the opening data of the injectors:
Flowrate corrections of 1st and 5th injectors are quite different from initial values. Opening time in idle of the injector of 4th cylinder – reduced (obviously, the injector of cylinder No.4 is leaking in closed position).
Last test of the injectors. Indicates strong flowrate correction for the 3rd injector in Homogeneous mode.
Idle, corrections of injectors of cylinders No.5 and No.6 in Stratified charge – close to redline.
Medium load mode, Stratified charge – massive flowrate correction for the 1-st cylinder.
Idle, the engine works in Homogenous mode:
The efficiency of cylinder No.1 – increased; cylinder No.6 – reduced (remember – in the 2nd image, it was increased!).
Here, Lambda values by the banks, when driving with speed 100km/h:
In the 1st bank – at least 30% more fuel, as it should be!
And here, the Overrun mode:
Here. The confirmation of the fact that the injectors of the 1-st are strongly leaking in the closed position! The Offset value of the NOx sensor did not lie!
Here, the data of the NOx sensor, obtained while driving with speed 100km/h:
In the exhaust – air leftover, exhaust temperature around 500oC! Current confirmation that the individual fuel mixture of the cylinder (due to injector problems) is entirely incorrect!
This time I can only repeat DO NOT try to “clean” the piezo injectors! The only solution for this car – replacing the injectors.