Towing TT yesterday and halfway to destination started getting a shudder in the lower RPMs. When she downshifted and got the RPMS up she ran like a top.
Pulled in and heard a puffing sound (first thought was another plug getting ready to pop!). Investigated and the weld leading into the muffler is broken on the topside. (whew!).
There are no error codes on PCM but she idle rough......almost like a misfire. So can the exhaust leak cause the rough idle?
Thanks,
Jon

 

IMO, if the leak is after the cat it would be unlikely it would cause a misfire or hesitation.
You probably had the small misfire and the cracked weld is now letting you hear it.

 

Thanks for the input. It's really acting like a coil. Without a code error I don't know which one to replace.
I remember there being a way to check the resistance across a coil. Anybody know how?
I'll post another thread asking just to make specific topic.

 

A few on here have purchased 1 new coil, and have tried 1 positition at a time.

You may just have a bad batch of gas, it's becoming a nightmare lately.

Good luck, sounds like a painless repair.

 

Has folks been dealing with bad gas? Is that common? I've never had that experience. We are at camp and decided since my inlaws are coming to visit and most of the coils appear factory original (I've replaced one and two others are aftermarket) I am having them pick up a full set of coils. I'll replaced the seven old for sure then see where we are at. Something that probably needs done anyway with 175k on it.

 

No an exhaust leak won't cause a misfire........that's explosion byproduct. (history).

 

I got a fill up last December that cost me about a grand!
My Benz worked itself out, but was not that lucky with the ex.

I did my coils at 140k, just as preventive maint.