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CL600 '00 5.8L V12
230 Posts
Discussion Starter · #1 ·
I have got issues with blue smoke coming out of the exhausts together with misfires upon cold start.
This morning I undid the oil filler cap and cranked the engine; the oil filler cap started to dance around for a brief moment. By the time the smoke was stopped, the cap settled.
I suspect that I might have a blow-by issue, which is quite common for this engine.

The car also starts to misfire when the temperature is rather low; at around 7 degrees C. When the engine warms up a little, I can restart the engine and the misfires are gone.
I'm not sure if the misfires are caused by the oxygen sensors getting fooled from all the oil burning.

When the engine cold starts, the RPMs go high, as you'd expect, but then it is barely able to keep itself running. Pressing the accelerator does not rise the RPMs by the amount you'd expect. Sometimes the RPMs do respond to the accelerator pedal getting pressed and then the engine runs ok.

I used catalytic converter cleaner to clean my cats, as I do have some cat efficiency codes.

In document GF07.61-P-3011F
There is an section stating:
"Post-start enrichment compensates for the fuel which precipitates on the cylinder walls. The fuel-air mixture is enriched sufficiently until a certain engine speed has stabilized (e.g. 1500 rpm with no gear engaged at +30 °C coolant temperature for about 30 s)."

Post-start enrichment is not happening as the engine does not rise to 1500 rpm. It did do that, but then I resetted the ECU and it stopped doing that.
The cold-start checks on DAS look ok, apart from the ignition angle being to low and the post-start enrichtment and TWC heating not being active.
The retarted ignition angle is probably due to the incorrect mixture.

Does the ECU shut-off procedures (post-start enrichment and TWC heating), if it measures that they are not working?

I've cleaned the PCV system venturi valve about 10k~15k km ago and it stopped to produce smoke upon cold start after that, I've replaced it about 2k km ago, as the old cover was broken and oil was seeping down the engine.

Last november, one of the coil packs went and the car started to gradually produce more and more blue smoke upon startup. I guessed this was due to fuel and oil mixing or something.
It took me about 1 to 1.5 months to order/receive/install the new coil pack and I was driving around with half an engine until that point. I did not disconnect the injectors, so the cylinders probably got washed everytime on startup.

I verified, with an oscilloscope, that the voltage transformer is still working properly upon cold start.

I did notice that the oil was had a nice metalic cloud, during the last oil change. I thought that those where the ZAS actuators since they are ratteling like crazy when ZAS is turned on.

I tested compression on all cylinders and there where a few lower ones.

Values are in bar; update: my method of measurement is probably not right and I'll have to do these over again
1: 9.6
2: 8.2
3: 6
4: 9
5: 10
6: 10.1
7: 11
8: 11
9: 10.5
10: 9
11: 10.1

This weekend I did a smoke vacuum test and the results where quite confusing. With the PCV system connected, alot of smoke came from underneath the intake manifold.
With the PCV disconnected and my pinky plugged in the hose that comes from the oil water cooler inside the valley of the V12, there is no smoke.
My guess is that we are lifting a gasket of somesort, by using positive pressure (around 1 bar) at the crank case when it is actually designed to handle negative pressure.

At this point, I think I either still have a vacuum leak, my fuel filter is clogged/fuel pump is not working properly or my injectors are shot.

Any suggestions? I'm kind of lost at this moment as there where a lot of problems summing up at this point. (Ignition coils, voltage transformers, oxygen sensors)

CL600 '00 5.8L V12
230 Posts
Discussion Starter · #3 · (Edited)
Any suggestions on tracking down the vacuum leak? I see alot of smoke coming from underneath the intake manifold (from my smoke tester) but I can't really see where it comes from.

Please do keep in mind that it only smokes big time, when the PCV tubing is connected!

I've replaced that gasket 6 maybe 7 times now, so you'd think that I'd be good at this point.

Also, the LTFT's are not ridiculously high or something

@Kraut56 do you have any additional insights on this issue?

CL600 '00 5.8L V12
230 Posts
Discussion Starter · #5 ·
I've replaced the fuel filter, runs much better, but the fuel rail pressure only goes up to 1 bar without starting. When the car runs it will slowly go up to 3.6 bars. I'm still suspecting the fuel pump to be bad too, as it made a strange noise during the fuel pump test when DAS was connected.

How quickly does your fuel rail pressure rise?

I also redid the smoke test, this time with me blowing on the regulator. Took quite a breather to get it done, but I saw no smoke.
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