Dragonflyer

My wagon is 2008 R350 4Matic with 88k miles & serial number outside of balance shaft problems.

Symptoms: engine starts and runs smooth but surges when coming to a stop and throws P0016.

Preceding: timing chain replaced 18 months prior with new guides, chain tensioner & sensor wheels, balance shaft sprocket checked ok but the chain tensioner that came with the kit was probably not installed correctly resulting in rattling noise upon engine start. That rattle has gone away after I recently installed new tensioner but resulted in code P0016 generated as soon as engine warms up. I tried two new magnets and swapped all but one (behind the steering reservoir) cam sensors with the same and only code P0016 coming back (no P0017). With bank 1 intake magnet out, I tried actuating the VVT valve stem by hand and it felt smooth, same as the the valve on the opposite bank with which I was swapping the magnets. All sensor wheel marks (with exception of one behind steering reservoir) are dead center at 40 degrees. I am using a generic code reader and do not have the ability to see DTC codes like 1208.

Asking for help before throwing more money at it.

Cheers!

efzauner

following
I just started hearing the knocking on cold start figuring its oil pick up seal (I told the mechanic before he changed rusted oil pan but brushed me off) So I am not sure if its the oil pickup seal or the camshaft issue. I do throw code P054 Cold Start B Camshaft Position Timing Over-Retarded Bank 1 This gets thrown on cold start if I dont give gas during the rattling/knocking.

efzauner

you may want to post this on other MB forums here with M272 engines as they are more popular. Sadly R class owners here are getting sparse.
Love the car to bits. Hate mechanics shops.

Dragonflyer

It wasn't a knock in my case but a rattle, which would go away immediately once the engine started and it stopped doing that right after I replaced the tensioner. I know it's not a balance shaft because I did have a chance to inspect it when swapping the timing chain and chain guides for which I did have to pull the front cover and both heads. The engine power surges upon slowing to a stop do point towards VVT heads. And that again requires the new chain and tensioner along with $1000 in cam gears and oil valves

I do love my R and am willing to go all the way to get her done. Thank you for pointing me to the M272 forum.