W202 Over revving on cold start

[WHISTY]

High new here and need a little bit of help with a couple of things

My C280 Sport 1995 over revs on cold start, maybe up to 2500 RPM & am worrying about damage to the engine. I have to put it into gear very quickly to drop the revs. It only does it during cold weather, it was 10c this morning and started normally. Anything under that & I get the problem.

Somebody suggested that the MAF might be at fault. Does this sound about right? There are no other symptoms of the MAF causing problems. Don't really want to spend approx £170 for nothing!

Anybody have any ideas what's causing this & a way to fix it please?

Any help appreciated

 

[Shane10010]

Hi,

Anyone know if this problem was sorted?

Shane

 

[Stratman]

The ECU can hold onto high revs and low gears in order to speed warm up. It may be normal behaviour.

 

[Shane10010]

Hi,

I wonder if that was Whisty's situation.
I have had my '95 C280 for about six weeks and until this last weekend the revs at hot / cold start have been perfect.

In my wisdom I decided to clean the MAF with Electrical cleaner and the The ETA with the appropriate carb/ETA cleaner.

After reassembly, the car will rev substantially higher than before then eventually settle down after a few minutes. This happens regardless of whether the car is hot or cold.

Any ideas on what to check / replace?

Thank you in advance.
Shane

 

[dalmiester]

My '94 C280 sport has been doing this after a coil blew and the car ran for a mile or so not burning fuel in two of the cylinders. I was wondering if the O2 sensor had suffered damage from the unburned fuel. When I start up the revs can hit 2000 rpm but does settle down. However idle can vary from 750-1000 rpm and smells rich.