After the correct re-adaptation of the engine, the owner of the car sent me new data with additional remarks:
a. the idle has improved significantly;
b. the torque of the engine in low RPM has increased;
c. When performing rough run tests at increased RPM, the uneven performance of the engine can still be felt. This unevenness can be felt when driving with very low required torque. This should not happen to the car, which costs a 6-digit amount.
Here is how the idle looks now.
First bank:
And the second bank:
The Miracle has happened! The injector of the 2nd cylinder has “repaired itself”! It’s not a sign of any performance problems!
Here, this is another (one of many) example that the statement of many “specialists” that “the engine will adapt itself, just drive” is false!
Why so?
There are several reasons, but this time, the situation is following:
a. obviously, in the past (probably due to a worn-out spark plug or some ignition coil problems), cylinder No.2 has had misfiring problems;
b. due to these misfires, incorrect injector adaptations have been created (reason – DME poorly identifies separate misfires and counts these unsuccessful work cycles in the common “basket” of the adaptation creation);
c. thanks to incorrect adaptations, DME “hysterically” (incorrectly) reacts to the requests to slightly upgrade the fuel injected by the injector;
d. thanks to the “hysterical” DME reaction, the short-term fuel mixture in the cylinder was very un-optimal, which sometimes provoked new misfires, in such way making the situation even worse;
e. even later, when the initial problems with the ignition were solved (but nobody has “told” it to DME – did not perform the re-adaptation), irregular misfires continued because DME continued to react inadequately.
Note. The fact that the torque of the engine in low RPMs increased is not surprising. Cylinder No.2 “takes care” regarding the turbo aggregate of the 1st bank exactly in low RPMs. While the 2nd cylinder was misfiring, the turbo aggregate of the 1st bank was not with full power. Noticing the problems in the 1st bank, the turbo aggregate of the 2nd bank also was slowed down. As a result – the engine did not develop the full power/torque. Now, this problem is solved.
But let’s see how the engine performance looks in the problematic mode – 1000 RPM.
First bank:
And the second bank:
Here, we don’t even have to zoom in. We can simply see that “everything is bad”. What happened to the engine? The problems are in two banks, in addition – for all cylinders! The engine is suffering! No, these are not misfires but continuous unstable mechanical efficiency of all cylinders!
In addition, as previously – the actual (bank/average) fuel mixture is correct; LTFT – is also correct.
What could cause such symptoms?
There is one hub, which could be the culprit. This hub is VANOS. I asked the owner to perform data monitoring for this hub. About results – read part No.3.
