1980 450SL very rough idle when cold - PeachParts Mercedes-Benz Forum

xkeots · #1 01-16-2006, 11:50 PM

Hi,

I recently bought a 1980 450 Sl with 68,000 original miles. It was sitting for a few years.
I have done plugs,coolant,oil & filter,air filter,gas filter, brakes, tranny service and filled rear, new exhaust.
Even before I did all of this when I start the car it stalls after the first start as soon as I press the accellerator pedal. It will do it the second time too. Once I start it the third time and press the pedal down and up or force drive it (from about 1,500-2,500 RPM) it runs but rough, almost like it's breaking up & missing like it needs a choke. Once the temp gauge gets to 50 it starts smoothing out and once it hits 80 you can't feel the motor running and it drives perfect after that till the next morning. I am not sure if it needs a warm up valve or something similar. I don't want to buy what I do not need.
I hope that you can give me a check list or a possible part to start with.
I have been working with cars for many years but I am new to the W107 and this list.

Thanks
Jack

mbdoc · #2 01-17-2006, 08:17 AM

CIS injected cars are VERY dependant on "changing" fuel pressures.

The "warm-up" regulator is the most important piece of the system.

Since the car sat for several years I would bet that the warm-up regulator is ALL gummed-up. Also the fuel tank.

Bosch has started raising the $$$$$ on those & all CIS related parts to the point that some cars aren't worth fixing.

Checking the control VS the system pressure is a STARTING point.

halman2228 · #3 01-17-2006, 08:19 AM

...include warm up regulator (if you have one -I'm not sure), dist cap & rotor, plug wires and more.

Search for "rough cold idle" to narrow down the list - if you replace everything (throwing parts in) you probably have enough money to adopt me

Good luck & keep us posted,

Kevin

EDIT: Looks like MB Doc bet me to it by a couple of minutes. He knows his stuff - follow him...