I have a 1999 ML320 that is idling rough. We ran a code search and it came up EGR flow. We replaced the EGR Valve but it's still running rough, but only when idling or when stopped. It seems to run fine on the freeway. Any suggestions?

 

Did you check to see if the tube was blocked? I changed my EGR valve and it turned out that the problem was the tube and not the valve.

 

I will check that tonight. I had a MB tech tell me the same thing. Can I ask you a question on this though? When you changed the EGR valve, there is a hose with a round end that doesn't seem to go anywhere. Does it just hang loose or should it be attached to something?

 

I know the part. I had the same question. I was told it is just supposed to hang there. Still, Ichecked the engine for something that would connect to it and found nothing. I've been driving with it just hanging there for about two years now and have had no problem. About a month ago, I was in the engine bay and saw it and decided to ask the question in another forum and was told again that it's supposed to just hang there.

 

By the way, I have the same vehicle as you (99 ML320) and my tube was completely clogged. One guy posted pictures of his clogged and cleaned tube on Benzworld.org; you can do a search on that site if you'd like to see the pictures. Sadly enough, mine was worse than his. He used gumout to clean his.I don't recommend buying a new one. Once they're cleaned, they are as good as new.

 

Thank you so much for your help! We cleaned the tube out and it is running great again. I just wish I would have known that before we spent the money on the valve, but you can't have everything......Thanks again!

 

where is the EGR located? can you provide a pic and how did you clean it.

thanks

 

The EGR valve is located behind the engine near the firewall, just about dead center. You will have to remove the air intake hose to get to it. We actually didn't clean the valve itself, but the tube that runs to it. We had replaced the valve and it still didn't work. We then pulled the tube off and it was clogged. We took a small flexible wire brush to clean it out and ran an air hose through it as well. I don't have any pictures of it though. Hope this helps!

 

That hose connects into the back of the block! (Is the car stuttering and wont stay running?)

 

Here's a pic of the valve and line. Unfortunately the EPC doesn't show it in relation to the rest of the engine.

We always replace the line the nut and ferrule and the gaskets with new.