It's been a while since I've posted but I've FINALLY figured out what was causing all of my rough idle, fault codes, and general poor performance issues. I'm not a mechanic, but I've sort of had to become one since the MB dealership AND an independent shop wanted to charge over $5k to "fully diagnose" what was causing the CEL. I decided I was NOT going to pay those prices and went about diagnosing and troubleshooting and fixing this thing myself. I got a scanner (two actually) and went about teaching myself and learning about how stuff works on these cars. And after over a year of learning, making mistakes, linging parts, chasing red herrings and going down blind alleys the simple fix for the problem was replace the gasket that separates the two halves of the throttle body 'elbow', and then make sure the elbow was fully seated onto the throttle body. THAT'S IT!! I was getting P0171 and P0175 codes which indicate a potential vacuum leak. So I started focusing on where a vacuum leak might be found. And with the help of some smoke, I found the location of the leak and sealed it and boom!! She's back on the road! The car has been running smooth as glass and after close to 2 years of sitting in the garage, and I've put almost 150 miles on it in within the past week or so! No CELs!! Well, I'm not quite out of the woods yet. I'm getting some SBC errors, but that might have a little to do with sitting for close to two years. Bt I'll create a new post for that.

But the ASE Certified master mechanics at both a MD dealership AND an independent shop wanted to charge me a crap ton of money to fix a bunch of extraneous stuff, but neither place wanted to actually diagnosed the error codes. It took me (a non mechanic) 18 months to figure what a code was, what the codes meant, and how to resolve the issue. But I would think experienced mechanics would have been able to spot this in a matter of minuets, or at least check the obvious stuff. But anyway. I fixed it myself and I'm on the road. So if anyone is getting lean codes, check the gasket that separates the upper part of the elbow from the lower part of the elbow, and then make sure the elbow if fully seated onto the throttle body. It might end up being a quick and easy fix.

I hope this helps someone!!!

 

Congratulations on your perseverance and your ultimate success!

 

Glad you found the issue. I think that many newer/younger/less experienced technicians are taught to use the computer as the first step in diagnosing an issue rather than using their eyes and and intuition first and then the computer.
If you’re in the USA, the SBC may still be under warranty by MB. Have the dealership scan the codes to see if it may be covered. Better to have them pay for the repair rather than you.

 

Thanks for the info. Mine is a 2009, so I doubt it's still under any warranties. But I'll definitely check. Thanks again!

 

I was told by a MB guru that SBC Warranty is 25 years.

 

Good to know! I'll have to give them a call. THANKSA!

 

Yes in the US 25 yrs and unlimited mileage, unlimited number of owners. But what makes you guys thinks there's an SBC issue?

 

OP mentioned SBC errors in the first post.

 

I think this reply was for my other post on the SBC issue.

 

Good job finding the bad MAF. Another tool to use is unplug the MAF , the car will still run but on predefined values and and not cause any problems other than lack of performance.
What code reader are you using?

 

Hi Maxorbit and thanks for the tip. I started with an ICarsoft scanner (which I don't recommend because it just unexpectedly stopped working). Then I got a BlueDriver unit which still works fine and the phone app stable and works great. Then y I got an Autel MaxiPRO unit. I would recommend both units, but the Autel is definitely a very powerful tool. That said however, there are lots of other scanners out there that can basically do the same thing, are a LOT less expensive, AND provide software updates WITHOUT having to pay or an annual membership. So do your research before purchasing one. The Autel unit came in right at $1k, and I would have not spent that much if I knew then what I know now.

 

it is mine is 03 and dealer did it last month under warranty. No charge at all to you

 

Thanks for that tip Change78! I took mine in this week, fully expecting to be handed a bill. But they replaced the unit, with no charge and no questions asked!!
SOWEEEET!

 

Great info. Part numbers please!

 

Thanks for sharing what scanners you used, sorry to hear about the experience with Autel but I am glad everything worked out for you in the end including the SBC code. Kudos to you!

 

Awesome post, thank you so much for sharing. Glad you found the leak, although it took you a lot of time but you wouldn't otherwise be able to learn so much if you just hand people the money and let them do it.

 

Another thing is, since you did it yourself, you know you did it and it was done properly, unlike these guys. https://mbworld.org/forums/e-class-w...ispreloading=1
Which is ironic because these technicians are literally trained years by MB to do what they are asked to do yet they still mess up something so simple.

 

I know, right!?!? Here I am, a frikin novice with ZERO training as a mechanic, but was able to figure out what the problem was. And it's not really that I figured it out necessarily. But rather it's more that they were dismissive and just figured I'd throw money at them, instead of just looking and discovering what this was a SUPER SIMPLE fix. It just goes to show you that everyone should buy a scanner, learn how to use it, and NOT be afraid of turning a wrench on their own car. You'll literally save THOUSANDS!

 

Good for you!

 

Part numbers please? Thank you

 

I purchased for Pelican Parts and I "think" the part number is 2721410880. But I also ordered one for my R350 which has a M272 engine, this might be the part number for that vehicle. I'm still trying to find the email with the order and part number, and will update if I find it. But what you're looking for is a "Mass Air Flow Sensor Gasket". Also, there is an upper and a lower one. And in my case, it was the upper one that had the leak. But if you can get (or find) both, I'd get both.

Hope that helps.

 

The MBZ on-line certificate hilights the replacement of various components of the anti-lock braking system, including the most expensive part, the SBC module.