Mercedes C200 Kompressor timing chain

I have a Mercedes W204 C200 Kompressor where the teeth on the variable valve lifters were almost completely worn away. The car was still running, but poorly.
Okay, I've now replaced the timing chain and all the gears, including the variable valve timing unit. I started the car, but it's only running on 3 cylinders. The error memory shows a misfire on cylinder 3, so I'm going to check the ignition coil on cylinder 4. Zyl and Fehler came along.
Today I installed a new ignition coil, started the engine, and it ran on all cylinders. I let it run for a while and then took it for a test drive, but during the test drive, I noticed that it was misfiring.

Quickly performed a compression test with the oscilloscope, getting readings of 100%, 96%, 100%, and 77%. Then, I manually measured the compression in cylinders 1-4, which resulted in readings of 11 bar, 11 bar, 4 bar, and 0 bar. Again, using the oscilloscope: 100%, 100%, 78%, 50%.

Cylinder 1 & 2 pressure drop test: 5-10%. Cylinder 3 & 4 pressure drop test: 90%. "When I blow into the number 4 cylinder, air comes out of the number 3 cylinder's spark plug hole and also from the throttle body."
When I blow into the intake manifold, only air comes out near the throttle valve.

Okay, I've re-downloaded the VDD again, and the timing values are as I set them.

"Once it has cooled down, I will take another look inside with the endoscope."

What could have happened? Why did it run normally after the initial start and during the warm-up phase, and then suddenly lose compression in 2 cylinders?

I have to mention that I used a FEBI NW timing adjuster and an INA timing chain, as the original parts are prohibitively expensive.

Here are the values from the NW adjustment during driving: in the LL (left lower) area, the exhaust valve was at -115 and the EV (exhaust valve) was at 115. Does anyone know what this should be?

Hi,

Assuming there are no other mechanical defects, such as general wear and tear (what happened to the material the "teeth" of the old... are made of?),
Assuming the variable valve timing system is working correctly and the valve timing is accurate, I can imagine the following scenario:

Quote:

What could have happened there? Why did it run normally after the initial start and during the warm-up phase, and then suddenly lose compression in 2 cylinders?

A possible cause could be a leak in the cylinder head gasket at the bridge between the 3rd and 4th cylinders. The cylinders only start working properly after the engine has warmed up.
Then the pistons push the contents of the combustion chamber back and forth across the damaged area of the head gasket, but sufficient compression is not achieved.
I've seen damage like that before on a 1.3-liter engine. Polomotor.

Quote:

When I blow into the #4 cylinder, air comes out of the #3 spark plug hole and the throttle body.

This could mean that the camshaft is positioned at top dead center (TDC) for the ignition stroke on the 4th cylinder (with all valves closed), and the compressed air is finding its way through a leak into the 3rd cylinder. Cyl.
and from there, through the open intake valve, to the throttle valve.

Quote:

When I blow into the 3, only air comes out at the throttle valve.

That could perhaps be explained by the path of least resistance.

These are just my speculations, perhaps the endoscopy will shed more light on the matter...

Best regards, Richard.

P.S.
There is nothing against using Febi/INA.

I had also considered the possibility of a ZKD issue, but it doesn't quite fit that there's no air getting into the fourth cylinder when I blow air into it from the third. I'm going to try it again with 10 bar this time; right now, I'm only testing it using the pressure loss tester.

I quickly took a look with the endoscope, but unfortunately, I can't rotate it, and the photo quality is very poor. However, I'll try again on the 4th. "Zyl is a valve that is completely wet/oily on the intake side, and I see something on it that I don't have on the other valve, highlighted in red."

Hello,

Does the crankshaft timing mark align perfectly?

To me, it looks like the timing might not be quite right. It's hard to tell from the pictures.

What do the gears of the crankshaft look like?

The chain must have 142 links.

The valve timing for the 271.950 engine is as follows:

Valve timing for the intake valve with a 2 mm valve lift and a new timing chain.

opens after OT...before °KW OT 25...5

Valve timing for exhaust valve at 2 mm valve lift with a new timing chain.

opens before UT...closes after °KW UT 24...16

A colleague had a similar problem recently where the variable valve timing system wasn't working correctly after a chain replacement, and it turned out that the oil filter was clogged with debris from the gears!

Have you checked the connectors/pins of the variable valve timing actuators for cleanliness (oil)? The wiring harness is known to draw in oil due to the Venturi effect, and it can also affect the camshaft adjusters.

You can deal with the variable valve timing units at the end; the engine must have compression in every position of the valve timing units.

Best regards,

Michael.

Several markings had already been made on the pulley, and it was also cracked. I set the timing mark based on the piston position. The crankshaft sprocket is also new, as are the oil filter and oil. I didn't notice any significant wear debris in the oil pan, nor in the oil filter. And as I said, after initially replacing the ignition coil, the engine ran on all cylinders, but after the test drive, it no longer ran properly.