1984 190E starts smooth, but after warm up it runs rough
 

I have 1984 190E that starts smooth, but after warm up it runs rough and if left at idel it will die down. light dark exhaust comes out of exhaust pipe and you can smell a rich mixture. any help would be appreciated...

email: Prgaw@msn.com

Thanks
Jim Garza

You may have a vacuum leak.

Remove air filter box and spray some plastic/rubber friendly fluid like electronics contact cleaner that will disapate quickly around the injectors, and vacuum hoses.

If no vacuum leak, check the Idle Control Valve, remove for cleaning using a Carb Cleaner spray until it come out clean, rattle it couple of times during the process and then finish with a bit of silicon based lube, re-attach. It might also help to check the ohms on it to insure it is within tolerance.

But I default to a vacuum leak.

Personally I found a huge leak on injector #4, She also started right up, did the warm up stage then when she drop she felt she would die. I popped the idle control breather and she immediately died.

Jim

1984 190E starts smooth, but after warm up runs rough
 

Thanks i will give that a shot and will keep you posted on how things come along..

Jim Garza:)

Re: Rich running after warmup

There are two external mixture control devices that are in play. (External to the fuel distributor [FD], that is.)

1) The warmup regulator [WUR], which contains a heating coil, that if not functioning, will cause the WUR to remain in the rich control mode. The WUR also contains a manifold absolute pressure [MAP] sensor. If the vacuum line to the MAP is leaking, or the seal of the MAP section of the WUR is leaking to atmosphere, the mixture will be rich.

2) The frequency valve, which is controlled by the O2 sensor in the exhaust, and the electronic control unit that processes the O2 sensor signal, and thereby controls the frequency valve. If the O2 sensor is defective, its control unit will keep the frequency valve in the default mode, which is somewhat rich.

Thanks for the help on this concern. The MB has been in my garage just waiting for me to make the time and take care of it. My wife has asked if I could get it fixed so she could start driving it, but I just have to make some time and get it done. Really appreciate all you suggestions and support.

Thanks again
Jim