320E (My first Gas MB) Misses and sometimes smokes - PeachParts Mercedes-Benz Forum

777funk · #1 03-01-2010, 11:58 AM

Quote:

Originally Posted by babymog

If the coil pack fails, the computer is designed to sense no fire in the cylinders, and cut injection / fuel to those cylinders. It does it, I've experienced such, and that is to save the cat plus emissions.

First thing to do is to build / borrow the Arthur Dalton design code reader (around $10 in parts) and read/reset/read the codes. Might be in limp-home mode already and have some issues.

Also, pull the vacuum line from the fuel pressure regulator (driver's side of the head, front of the fuel rail) and see if a ruptured FPR diaphragm is pumping fuel directly into the vacuum line, sounds likely.

Thanks for the reply. The Check Engine light isn't on. I'm assuming that means no codes or that the bulb is burned out. I'll have to turn the key and see if it lights up.

So fuel into the vacuum line... what indicates this is a possibility?

samiam44 · #2 03-01-2010, 12:09 PM

Hold the phone and back up a set.

THE FIRST CHECK needs to be a compression test. Make sure the motor meets before proceeding into coil packs, wiring harness, or fuel system problems.

Michael

d.delano · #3 03-01-2010, 12:52 PM

w124 for $200 what a bargain!

777funk · #4 03-01-2010, 01:20 PM

Quote:

Originally Posted by d.delano

w124 for $200 what a bargain!

It's in good from 20 feet away condition too and I love the color (charcoal almost black metallic). There are some defects but you have to look for them. It's a sharp car. I like the look of the later W124s more than the earlier ones like my 87.

But of course, possible bad headgasket and other issues. But still... for $200!

babymog · #5 03-01-2010, 01:24 PM

Quote:

Originally Posted by 777funk

Thanks for the reply. The Check Engine light isn't on. I'm assuming that means no codes or that the bulb is burned out. I'll have to turn the key and see if it lights up.

So fuel into the vacuum line... what indicates this is a possibility?

Might mean the CEL iis burned out, does it come on with the key on before starting?

Fuel in the vacuum line will go directly to the intake, very rich at idle.

The coil pack and plug connectors are certainly another big possibility, and very common. Original blue-stickered Bosch coil packs were especially problematic from what I've read.

Next possibility is the engine wire harness, check it over, do a search here for wire harness issues on the M104 (as well as other early '90s Mercedes).

Compression is unlikely a problem IMO, a highly unusual failure in the M103/M104 engines.