This time – a quite hopeless story of some N43 series engine.

This engine has had problems with vibration in idle, especially – during the cold start. The injectors were tested and approved as good. Installed back in the engine. Cleaned. Zero progress. Tested repeatedly. Repeatedly approved as good. Still – no progress. When all possible scenarios were tested, and the owner ran out of ideas, he approached me. 

Data of warm engine (including injector adaptation) – correct. Here is the screenshot from the cold start video: 

It is clearly seen that the injectors of the 3rd and 4th cylinders (by placement) are leaking (marked with red).

So that there is no doubt regarding diagnostics reliability, I asked the owner of the car to take out the spark plugs:

Here, the confirmation – it is seen that the fuel mixture in cylinders No.3 and No.4. is very rich!

This is only one of many examples that repeatedly confirm that “testing” of these injectors on the stand is completely useless! Even more – it can permanently damage the injectors! Why? Read here.

The solution is simple – diagnostics. Diagnostics (live) data will show where the problem hides.