azamora925

I have a 2001 Mercedes Benz c320. it didnt want to turn on one day out of no where so i changed the fuel filter, fuel pump and the accelerator. None of it worked, so i found out that the intake manifold was cracked so i replaced it and vuala! It works! BUt! When i come to a stop, my car starts to shake as if it were about to turn off. Happens every 2-3 stops. What can this be? Bad spark plugs? Because it definitely feels as if its getting bad gas mileage and its lost power. It stutters when i try to accelerate quickly? HELP !

azamora925

oh and quick question to anyone who helps! Does my 2001 C320 v6 have 12 spark plugs? I thought they only had 6 since its a v6. I'm still a newbie so cut me some slack! :P

Moviela

Check engine light on? You need to connect a scanner and see what codes are present. The engine is a "twin spark" design, so there are two plugs in each cylinder. There are four bypass hoses on the engine. At 12 years old they are hard as Pharoses heart. They should be changed. You might also have a dicey crankshaft position sensor. There is a possibility that the contacts on the interior of the throttle body are dirty.

Before throwing money at expensive new parts, do find a shop that can diagnose the problem. It generally takes a Star computer to do that at a dealer or a well equipped indie.

samaritrey

What are the bypass hoses you speak of?

Holmes5518

If you changed your intake manifold I'm betting on a Vacuum leak somewhere.

chazman

That's what I was thinking - air intake leak and running too lean.

Moviela

There are four hoses that connect to nipples () on the valve covers and direct the crankcase gases into the intake. There are three nipples, but four hoses. one of the runs has a splice in the middle, so that run needs two sections of hose. There are four different part numbers.

The hose is molded in the correct shape to fit and seal. New hose is soft and supple. It is easy to push on the nipples. You cannot remove the old stiff hard hose no matter how careful you are. It cracks and will create a vacuum leak.

http://www.pelicanparts.com/catalog/...FULEMI_pg2.htm

samaritrey

Thanks so they are the same thing as the crankcase breather hoses? That is what I have always heard them called. I have the 4 hoses in a box along with a water pump and a million other parts that are going onto THE C320 in the next few weeks.

Back on topic OP ... How many miles are on your car? When were the spark plugs last replace as well as wires? Also what about MAF and oxygen sensors?

azamora925

Thanks for the help guys. So I honestly don't know the last time the spark plugs were changed. I'm currently still paying it off from my uncle so I'm still in debt. Lol. It has 158k miles. I just bought 12 NGK iridium spark plugs today for $7.99 each so hopefully they are good enough for the benz.

chazman

NGK makes really good plugs, maybe even better than Bosch.

Khan28

You can pull 2 spark plugs out first and check them to see if they're in need of replacement before buying them. Whiles your at it clean your MAF sensor and TB. I had an intermittent rough idle when stopped at traffic lights and for the first 30 seconds at cold start and a cleaning took care of that. Hopefully one of your ignition coils aren't bad, on your twin spark motor those will be expensive.