89 300E, Rough Idle, hard start, stalling solved, thank you all

[rayhalks]

I agree with the plug remarks, on a older car the plugs don't make any difference. I changed back to the old ones and runs the same. Just a 40 dollar waste of money for me. Another thing I noticed on the car is when I get down to around 1/8th tank of gas or less the car picks up a little 'blurb' in the idle. I ran the car near empty and drained the gas tank and flushed it out. Put in good gas and another new filter and wow, what a difference that made. The sludge that came out was really bad and when the car ran low on fuel, it make a higher concentration of the sludge. If I used to refill the tank, the car ran great until it got under a quarter tank, now runs great, even on reserve. Sludge will not leave a tank, and no cleaner will get rid of it. I needed to drain and flush the tank.

And what I meant earlier by starting fluid was checking leaks as stated. You can also use WD40 or any spray parts/carb cleaner. They will all cause the idle to surge if a vacuum leak is found. You just spray the fluid on all vacuum hoses and connection until you find the leak. Good method since a leak may be non-visable to the eye.

[deathrattle]

"My problem was a combination of things, all stemming from what I believe was crappy,
dirty fuel."

WTF do you think your fuel filter is for? Lower octane fuel is not dirtier or less refined and is not harder to ignite, infact it combusts more easily.

[bisser01]

my frend in berlin just sent me an e mail that there is a purple whire 23/6 and if you conect it to the grownd it gets rid of the idle problem completly still tryng to figure out where this whire is.my car runs fine ive never done this before and just wanted to see if it makes a diference.looked at the manuel yestrday and it realy did say purple whire conect to grownd for idle problems.the bad thing is it dose not say where this whire is and my frend in germany whent in japan for vacantion no cell! as soon as he comes back ill ask him.i do have the wiring diagrames but still cant find this purple whire 23/6 man its driving me crazy if some one knows about this please post it mabe its one of the cure for alot of sick benzes with a rugh idle[;)]

[dandan300E]

Thank you very much for all of this information! I can't wait to get home to my tool box to try this.

I found some more info looking around on the web that I thought might be helpful to share in regards to the OVP:

When checking voltage at the pins of the overload protection relay pin 30 is hot with the key on and pins 87 are the output voltage to the control units. If the relay is blown there will not be voltage present at pins 87.

To be fair, this was copied from http://www.thebenzbin.com/mercedes-hard-start.html

Have a good one!

[:D]

[AntiJeffy]

Wow, i am copy and pasting this thread as a to-do list for this winter, I have a 89 300e with 211,000 miles and it resembles the problems you have listed almost note by note, although not exceptionally bad or annoying yet, run perfect 90%+ of the time. And it starts just fine on all of the frosty mornings we have had so far!
Tommorow I will get to test it out in snow though, that may be interesting.