shaun.barnard

Hi guys

Cant find a thread with this issue for a c 55. I went on a long trip and when I got back my rear bumper was black around the exhausts. Seems that the car is overfueling/burning too rich. What could the problem be? Could it be a dirty MAF or some kind of sensor fault? Its a '06 C 55 AMG with 140k km's on the clock.

Alswag

On these cars, cleaning a MAF is useless. You would need to buy a new one.

It could be a faulty fuel pump as well, and it's delivering too much fuel to the cylinders. Or the fuel injectors are crapping out. It could be a lot of things. I doubt it, but is your engine throwing a code? If not, get your cars' ECU read anyway via STAR.

Glyn M Ruck

The most likely cause of overfueling if you can see visible smoke is a faulty engine temperature sensor. The car thinks it's cold & goes into open loop mixture enrichment when hot.

Read codes with an OBDII scanner & post.

shaun.barnard

Hi Glyn, I had the car by a garage and the guy said I need to put dummy cats in because the previous owner had modified the exhaust so the ecu isn't getting the correct reading? I see though that there are 4 sensors on the exhaust so that should be right? Or could the o2 sensors be faulty or is the guy off track and u still think its a temp sensor or injectors?

Glyn M Ruck

You need to see what codes it is throwing.

Likely causes.

Temp sensor
MAF
Upstream O2 sensors.

Running with no Cats is illegal ~ At least fit primary Cats.

shaun.barnard

I have the car at the dealer as we speak and they said no sensor fault codes showed, as they checked for that as well, did a full quality check for me, and said that the wrong oil is in the car so they are replacing the oil. I suppose if the car burns 2lt of oil every 200km then the bumper will be black? Going to send me the list of faults but luckily the engine and gearbox is good according to them and that im happy about.

Glyn M Ruck

Get the right oil into the car but this is not an oil problem. As long as the upstream O2 sensors are good & in place the ECU gets the correct mixture data.

Does the car really use 2 litres of oil every 200Km?? If so there is something seriously wrong & yes you will have a black bumper.

If they say the engine is OK I presume they have done a leakdown test & compression test to prove that valve guides & rings are OK. If so then a breather or similar is blocked & building up crankcase pressure & forcing blowby.

Make them give you a Star printout & post what codes are displayed. You have paid for it & you own the data not them. Don't take any BS.

shaun.barnard

They refused to give me a printout, said they were not allowed to

Come to think of it, it used 2lt when I rode 200km the first time I got it and as I added Mobil 1 0w40 every time it started using less. About 2 weeks ago I went to cape town for a course and filled 2lt there and 1lt on the way back and the trip was about 1400km altogether. Well the proper oil is in now so I am just going to monitor it now. So that's done but now I have a new list of issues with the quality check, but small things like castor, rear lower control arm and pilot bushes etc.

Thanks for all your help, will let you know if its better or not.

Glyn M Ruck

These dealers are full of crap. If you pay for diagnosis you own the Star printout legally.

Boom vang

If your car was burning that much oil you would have an incredible cloud of blue behind you. Going through that much oil I would assume that you have a leak somewhere

shaun.barnard

Hi Glyn

Just wanted to let you know it looks like all is good after the oil change, went to PE yesterday, first checked the oil and said oil level is good then went on the trip and checked this morning and the oil level is still good, cant believe that oil type can make such a difference. They must've thrown some cheap crap oil in before they sold it. There is a hint of black around the exhaust tips but I guess that could probably be all the leftover s*&t in the exhaust that was blown out.

shaun.barnard

Just a pic of how the bumper looked when it had the wrong oil in.

Glyn M Ruck

Bit of a mess. I'm pleased it is behaving now.

VASHAN

Hi Guys i know this is a old post but im having similar issues.
My car throws a puff of blue smoke when i take off hard ...
the car is using alot of oil also but there is no leaks at all.I fill 1 liter of oil for every 500km but thats driving the car hard .It doesnt come up with any faults on Star .

I have full exhaust on the car with no cats as well as a software tune . I tried replacing the software with a different tuner it worked well for a month or so but back to its old crap now.

I was using Mobil 1 0w 40 but changed now to Shell Helix ultra 5w40

PLEASE HELP

Alswag

1L every 500kms is very excessive. ****, 1L ever 1k Km's is excessive. Get a leakdown test done, and check compression on all cylinders.

VASHAN

i have done a compression test all is fine . I also have a mate that has a stock standard 55 his oil consupmtion is also high whilst drivig hard