PeterS.

I have a 2003 Mercedes s600 5.5 v12. The car was driving fine and I took the car to the mechanic for an unrelated problem. I replaced the from hub assembly and did the alignment ($500). When I picked up the car, it didn't work anymore. When I turn on the car everything is okay but when I put it on drive it doesn't go faster than 5mph. In a pissed off manner I told the mechanic, "what the f... did you do!!!!" He hooked the car to the scanner and it is misfiring on cylinders 1-6, and number 12. Could it be something easy like something came loose like a wire or something. Or is it the coils? I have to add that when I start the engine everything seems fine but it still misfires and you could feel vibrations of the misfires when on park. When on drive the car doesn't move faster than 5mph and the yellow triangle comes on not the check engine light. I know that both the ignition coils and spark plugs were changed at 113,000 miles and I currently have 160,000 miles on the odometer. Any help would be greatly appreciated. Thanks everyone!!

tusabes

the fact the yellow traction triangle comes up and you have no power , plus you had wheel /hub work done suggests the mechanic either damaged or did not fully connect some wiring /sensor In the area he worked on. Most likely a sensor dealing with traction control and limp mode

often times connection are not fully snapped in

PeterS.

Does limp mode include misfiring in the engine. And does anybody know what could have been disconnected or damaged. I'm in the process of selling my car because I think it's the ignition coil or the ignition module. And I'm selling it too cheap, because technically it's to expensive to fix. If anyone can tell me what it could be or if I should tow the car to Mercedes dealership to have it properly diagnosed. Let me add, when it's on park the car accelerates when on drive it doesn't pass 1000-1200 rpm. Please help I don't want to sell the car that I have spent so much trying to maintain for nothing.

tusabes

Not rev past 1200 rpm is limp mode , not caused by coil. A Mercedes shop is just going to read the misfire code and start replacing parts

if it was running fine before the hub repairs , it's very likely related to a connector not properly reconnected

When you try driving it , hold your foot to the floor in the gas . Use an open road with no traffic behind you . Very very very slowly it should accelerate past 5 mph if you keep it floored

PeterS.

So what should I tell Mercedes when I take it for a diagnosis. What should I tell them to check, the connectors? I hate to be simple but what are the connectors and where are they located? I have no mechanical experience. I don't have money to spend on guesses. What do you recommend for me to tell Mercedes to check. Thank you for the advice "tusabes" and I should add I called the mechanic who did the work at 4:30pm (pacific time) today and he said he didn't disconnected any wires or sensors when he did the job. But it was running fine when I dropped the car off a few weeks ago.

Thank you for the advice "tusabes" And anyone else who could help.

PeterS.

Could it be a dirty engine? I have many pictures of the engine bay but I'm having trouble uploading them to this forum. My email is peter11773333@gmail.com contact me if you want to see the pictures.
Or how about a vacuum leak. I've heard of that term on other forums. What is that? And do I tell Mercedes dealership to check for vacuums leaks? My Mercedes always dipped on power every time it stopped on a red light or stop sign. It felt like if it was about to stall but never did. I'm scared of taking the v12 beast to the dealership and later have them tell me replace this , or replace that. I just start thinking about $$$$ that I don't have.

Thanks everyone!!

TenZero

To me, sounds like the tech either damaged or forgot to attach ABS/wheelspeed sensors. Lots of techs forget/mess this this stuff up, especially on an old S class which they aren't too familiar with.

PeterS.

So the abs wheel speed sensor can cause limp mode? If it does that could be that problem. Should I take it to Mercedes dealership and pay $160 for them to try and figure it out?

TenZero

No, you should take it back to the tech you already paid for the job, and have him fix it correctly. I've had techs install a wheel bearing incorrectly (backwards) and cause the exact problem you describe. (although it was on a Honda, and didn't cause limp mode.) On many cars now, the ABS sensors are magnetically coded into the metal of the hubs and/or wheel bearings. Improper installation can cause the ABS system to fault out.

PeterS.

I called the tech and he said he didn't touch any sensors. He said he didn't touch or unplug anything. He doesn't want to see the car anymore. Mercedes dealership should be able to properly diagnose right?

TenZero

You paid the tech to do a job. The car ran well before you brought it to him, and now it doesn't. If he f*cked it up, he should be willing to fix it. If he "doesn't want to see it again" then he is trying to f you. Up to you whether you let him. MB tech will likely not try to F* you, but you will pay double for him to diagnose and repair your problem. Also, the MB techs who worked on my car before I bought it did terrible, awful work, Orangutan level stuff. I will never pay them again, If I can help it.

PeterS.

Thanks for the tip TenZero I should take it to the original tech.

tusabes

If he replaced the front hub assembly he most definitely messed with your abs and wheel sensors

while he should be the one taking care of it , it probably is better to take it to the dealer .

What you tell the dealer is exactly what you told us , that it was working fine before the hub repair and now it's in limp mode . Bring a copy of the invoice from your repair so they can see what was done .

While the problem is very likely related to his work , there's a chance it could be something else , especially if it was left there a few weeks as you just now added. He could have let the battery drain and improperly jump started the car , or any other number of issues.

DrDoe

PeterS, Sorry to hear about your situation.
You need to check out the story I had under "No compression dilemma". It sounds similar...

PeterS.

The car was only at the repair shop for one day. I explained myself wrong. I guessing it is related to his work. I'll be taking the Mercedes later this week to the dealer for a diagnostic. Thanks everyone I'll be following up with the dealers diagnostic.