Ken Keith

Is it possible to check cam and ignition timing with a scan tool to get an idea of idler gear condition? I have a icarsoft v3 that can read sensor data but I have no idea what the original specs are for warm idle condition.

The car is an 07 cls 550 with 75000 miles, m273 motor built code 2739 30 088611, which I believe falls under the bad gears.

I'm trying to diagnose a slight rhythmic miss under warm idle. I believe it's a plug or coil but I was replacing a bad thermostat and decided to check the intake cam alignment for signs of the bad idler gear I've since learn these car came with.

I removed both intake cam positions, rotated the crank to the 305° mark and a stamp on the cams should be viewable and aligned within the cam sensor hole. While mine seem aligned they appeared to be closer to the top of the witness hole than centered.
It's difficult to see the alignment mark for the crank shaft but it was close to 305°, if I tried to adjust slightly either way, I couldn't get either cam to align in the center. The stamp always appeared closer to the top or bottom of the hole. It's not the easiest to see but I did take a few photos.

I was able to get the vehicle master inquiry hoping to see it was replaced. The only relevant warranty work I seen listed was Gasket cylinder head cover, ie (head gasket?) and closing cover camshaft oil Los (valve cover?) done in July 2011 @ 23,000 miles. Don't know what it means but It wasn't listed as a "campaign" like the other recalls done.

Is there any other way to determine gear health or timing chain wear without removing the front cover on the motor?

Ken Keith

Just did a compression test. I got about 150 psi across the board. Dry test with engine around 80-90°.

Ken Keith

Is there a place to find the factory data log specs for this motor? Things like timing, fuel trim, map pressure, service limits etc?
Is there a manual on disk or available for download somewhere?

95viper

There are videos online to insert a scope and see the gear. I replaced mine in garage. Big project. The front cover cannot come off unless oil pan is removed.