ok first i unintentionally ran out of gas due to a faulty gauge went to a mechanic because i didnt know it was out of gas they changed the cap and rotor and also put new spark plugs in and obviosly it didnt fix the problem eventually they put gas in the car and it fired right up but now the idle is surging and a ton of black smoke is coming out all they can tell me is that its running rich and they dont know what is wrong there isnt any diagnostic lights coming on in the dash but before occasionally the o2 light would come on so my question is what should i look to replace?could it be a bad o2 sensor? my car is getting plenty of spark and never smoked a bit before this could it be clogged injectors?and if so would it make it run rich? im really confused any help would be much appreciated ohh yea the car seems to run fine at higher rpms if that means anything thank you for your help

have u ran it empty before?

1: something he "fixed" wasnt right, are the spark plugs gaped properly, wires right, etc. etc.

2: running it low can get the old stuff, deposits, sludge etc. into the system, so it could be clogged injectors

3: running it low all the time can damage the fuel pump, but i kind of doubt it with ur symptoms

nope never ran it empty before the gas gauge read near a half a tank but the yellow light did come on so i dont know as for the mechanics doing somthing wrong its highly possible becouse i took it to the nearest shop instead of a mercedes specailist and i think they were in over there heads for now on i will only take my car to a reputable mb shop thanks for your help. someone also told me its a good chance my o2 sensor is bad but i dont know.

change it anyways. You can do NO harm by getting a new one (except your wallet, of course)
Good luck!

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J.H.
'86 300E

Before you spring for a new O2 sensor - you probably sucked crud from the bottom of the tank into your system. If the car ran good before it ran out of gas - chances are nothing is broken - so don't change parts at random - too expensive. I'd get a couple of cans of that fuel system cleaner/conditioner stuff from Pep Boys or other such place and put them in the gas tank and run it - you will probably see a difference after about 1/2 hour as it cleans your fuel system. Using logic - how can running out of gas cause your car to run rich - other than crud running through the lines? Worth a try and may save you more money.

If you suspect bad fuel and/or you don't know when your fuel filter was changed, change the filter.

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VR
1967 250SL

I was told by a guy that maintained humvees for the US army that the absolute WORST thing you can do is run them near MT or dry. The reason was because of pulling stuff out of the tank that don't need to be in the fuel system.

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Jim

ok replaced the fuel filter today and still is running the same also put fuel system cleaner in it so far it has had no effect the car still is running bad im thinking about breaking down and buying the o2 sensor but dont want to if it aint broke as i am running out of money very rapidly when i disconnect the wires from the sensor the car maintains a rpm of around 2000 and runs good does this mean the sensor is good or bad?could there be a problem with the fuel distribution thingy?im still at a loss and hope i find out whats wrong soon thanks for your help

What do you guys think about having the gas tank removed and having it flushed out and cleaned?? There is a place in town that does that. My car has almost 170k on it, and figured that something like this couldn't hurt it.

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'86 420SE Euro
904 Midnight Blue, Gray Velour
Dad bought it new, now I own it.

"A Mercedes-Benz is like a fine wine, it only gets better with age."

-UPDATE- today i replaced the oxygen senser with one from a 5 litre mustang it fixed my idle surging problem but now i have another problem the car idles smoothly now but hesitates really bad when i take off and is also still getting horrible gas mileage i would guestimate it at about 10 miles per gallon and i can tell it is still running rich and is also still smoking (black smoke) any suggestions as to what i should replace next?as of taking the gas tank to have it cleaned probably aint a bad idea if you have the money i dont but if i did i would i really appreciate everyones help you guys have been wonderful in helping me fix my old beater benz thanks again for the help

pieceofcrap300e

I think you should go back to the scene of the crime-

-Let's review ... you ran out of gas:

*OK it could be gas tank crap but sooner or later it should clear out.
*You had the cap, rotor and plugs replaced but still it runs like crap.
*You have changed the O2 sensor but it won't take a load.

My guess is to double-check the cap, rotor and plugs that were replaced.

-Question: MBZ cap and rotor? Plugs ... what kind? What are they gapped to?

My 2 Cents

I am no expert but I think your repair shop interfered with your airflow sensor screws. They are located on the fuel distributor and control the amount of fuel that gets mixed with the air. My guess is that in their effort to fix the problem they turned a few screws and have messed up you mixture settings.

i think rupert hit the nail right on the head becouse ive replaced everything i know of to replace (i figured it was a good idea anyway becouse most of the stuff looked like it hadnt been changed in a while)im going to go to the shop tomorrow and ask them if they messed with that stuff someone else had told me that might be the problem too.as of now my car is running pretty good with the exeption of a little smoke and a really heavy gasoline odor and im getting real poor fuel economy but other than that my car drives like a dream i am very thankful for everyones help!

hey Ricky,
maybe by now you'll have figured out what type of board this is. how bout changing that handle? nobody here really thinks of their rides that way. quite the opposite

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joE
1993 300e-2.8 - gone now <sigh>
"Do not adjust your mind, it's reality that's malfunctioning"
http://banners.wunderground.com/bann...L/Key_West.gif

Joe is right on. Please change your handle because it is offensive. You take your car to a mechanic that throws parts at it before he figures it is out of gas and then you replace the O2 sensor with a Ford part!!!!! I seriously doubt that the O2 sensor is operating properly for a 300E. My daughter recently had an O2 sensor replaced in her Saturn and the part is different for an automatic or standard transmission. "Cheapowner" would be a better moniker