MBDOC or anyone with current w204 experience (part deux)
 

2008 c300, 24k miles....

Recently had a CEL, dealer said the air filter housing seal was "crimped." No idea how this happened, but they wanted me to pay for it. I declined, they ate it.

The car had been running intermittently rough prior to that, which could be the seal, or not.

The last 2 days, when I start the car cold, it chugs, shakes and dies. I have to crank it again. Warm crank is no issue.

Cam magnets? Cam pos sensor? Fuel delivery? What could it be?

Car is out of warranty in 4 months, so whatever it is, it needs to be SOLVED and I need to point the dealer in the right direction quickly.

Without the SDS hooked to it it will be hard to tell what is going on with it.

A really common problem on m272 and m273 engines caused by someone not installing the air filter box correctly which can cause the rear seal (which goes onto the mass airflow sensor) to not sit correctly or tear the seal. This will cause the check engine light to come on with a short and/or long term fuel trim code at part throttle. And if you are still having a cold starting issue AFTER they replaced the seal, then it sounds like they may not have reset the fuel trim adaptation values after replacing the seal and the computer is trying to over compensate. Or it may be something completely unrelated, which is always a possibility.

No, this is a new issue. It has never flat-out jerked, sputtered, and DIED upon cold start until the past 2 days - in a row.

No CEL, no rough running after I restart it.

Make sure that they re-adapted the system & up-dated the software in the ECU.

Will do - thanks!

More info - gasoline vs ethanol
 

I've been running it on pure gasoline from the same place I fill up my SL, and when I switched back to Shell Vpower, it has stopped dying on the first crank. I know it takes a higher volume of ethanol to produce the same amount of power as gasoline, so I presume the ECU was running the mixture too rich on the "raw" gasoline? Still, it didn't die on the previous tanks of the same gasoline, but it does seem air/fuel/rich/lean mix related.

But surely it should have adjusted for the difference is gas vs e10, no? I doubt there's much data on running a 204 car on pure gasoline, but thought I'd ask.