2003 C320 -acceleration/Check Engine light problems.

[Chrisc320]

Hello All,

I own a 2003 C320. About a week ago I was driving, my check engine light came on and I started to de-accelerate. I could rev the engine, but it never went above about 30k rpm and would not accelerate over about 60 MPH.

Going up a hill felt like the car was going to stop. I was on my way to work so I barely made it to work, then didnt drive my car until it was time to go home ( 8 hours later ). When I got in the car no check engine light. Acceleration seemed fine. On the way home I needed to get above 60 and the check engine light came on, the car started doing the above. When I slowed down to idle, the car would shake like it was sputtering out and about to die. I could also hear a rattleing noise somewhere in the car.

I researched and everyone said MAF is the problem. So I proceeded to find out how to change it. I went out today:
- pulled the air filter case off
- found the MAF
- pulled it out, inspected it ( no visiable signs of wear or dirt )
- cleared the air filters
- put it all back together.


Started the car:

- Check engine light on
- no shaking at idle
- could still hear the noise.

Noise:
Coming from under the car, in what might be the exhaust/muffler.
- best way to decribe it is sound like a tiny pebble in there rattling around.

Things to note:
- noise is gone when check engine light is off and car is not experienceing the issue.
- if the car sits for extended periods of time , no issue with acceleration, until I hit a certian point ( varies, but if i give it quick gas, the issue pops up)

Any ideas?

 

[television]

The V6 is known for having broken CATs that rattle, they can block the exhaust but I have not known one unblock itself, and the engine light could be put on by the O2 sensor when the blockage occurs

 

[BlackC55]

Still sounds like an air mass problem.

 

[television]

As BlackC55 where did you buy the MAF from

 

[jberks]

As above, if it's never been done, change the MAF first. Issues are not necessarily visible. The juddering and lack of power are simply symptoms of the 'safe mode' which is commonly caused by the MAF.
My E240 did the same thing - new MAF (and O2 sensor) and she was sweet again. The MAF can malfunction and the car continue to run ok, it's only if the output exceeds certain parameters that the ECU shuts down, so the fact that it's running doesn't prove all is well, only that the ECU hasn't called the MAF a liar yet.
It could also be a blocked CAT as Malcolm rightly says but lets hope not. If it does turn out to be one, don't be tempted by a Qwick fit after market replacement. People normally regret it.
OEM ones are available outside the dealer network, but you may need to search a bit.