Sudden revving when shifting to reverse after cold start
Thread Starter
Junior Member
Joined: Oct 2011
Posts: 22
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2007 CLK 350 Cabriolet
Sudden revving when shifting to reverse after cold start
Hi there. As of a few days ago, my 2007 CLK 350 has starting revving repeatedly right after I turn the car on and shift it into reverse (my foot is on the brake so it's not actually going backwards but it revs as if it wants to).
Oddly, this seems to only happen the very first time I use the car in the morning. Subsequent starts later in the day are symptomless.
One possibly important note: this started happening right after I changed my own cam plugs, which I believe were leaking. Pretty sure I got the plugs in solidly, but installation required taking off the air intake apparatus and the three hoses associated with and then reconnecting. Wondering if I flubbed something during that process.
Any ideas?
Oddly, this seems to only happen the very first time I use the car in the morning. Subsequent starts later in the day are symptomless.
One possibly important note: this started happening right after I changed my own cam plugs, which I believe were leaking. Pretty sure I got the plugs in solidly, but installation required taking off the air intake apparatus and the three hoses associated with and then reconnecting. Wondering if I flubbed something during that process.
Any ideas?
MBworld Guru
Joined: Dec 2009
Posts: 10,782
Likes: 1,011
NO LONGER ACTIVE
Often, the cause of this is a vacuum leak that causes a rich mixture. To begin, with check, that the engine cover/ air filter housing is securely seated. If it is, start checking vacuum hoses.
Thread Starter
Junior Member
Joined: Oct 2011
Posts: 22
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2007 CLK 350 Cabriolet
Thanks Rudeney. I think you nailed it. Popped the air cleaner off again and then when putting it back on, I noticed it needs a swift push downward to full seal onto the air tube below it. Pretty sure I didn't do that when I put it back on before.
MBworld Guru
Joined: Dec 2009
Posts: 10,782
Likes: 1,011
NO LONGER ACTIVE
Yeah, been-there-done-that. On some cars, if it's not seated well, it will run great until you return to id;e, then the engine dies. In traffic At a busy intersection. With lots of impatient people behind you. 
Junior Member
Joined: Apr 2016
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C450 AMG
Hey guys, I got my 2019 c43 tuned end of Dec by Eurocharged. However, since then i have been driving very economically, as I had a few long haul family drives, and we have had bad weather (snow). Im worried my car as "learned" this.
Would I benefit at all from doing this retset? Does the method work on 2019 9 speed trans? I read somewhere i can unhook the neg terminal on battery and it resets trans as well.
Suggestions?
Would I benefit at all from doing this retset? Does the method work on 2019 9 speed trans? I read somewhere i can unhook the neg terminal on battery and it resets trans as well.
Suggestions?
