87 560SL Rough Idle - PeachParts Mercedes-Benz Forum

JFawcett · #1 03-05-2007, 11:27 AM

I have an 87 560SL with 96,000 miles on it.
It was in the shop for timing chain rail replacment, etc.
Car started idling rough when cold - once gets up to opertaing temp, runs great - slight hesitation, but nothing to complain about.

I have replaced the EHA Valve (two screws and a plug) - and now the car is stalling when cold. Starts right up and backs up fine - but when you put in drive and accelerate the car seems to flood and then stall. If you ease the gas pedal down, it seems OK - no power, but doesn't stall.

I have been reading on the forums that this problem could be the coolant temperature sensor? Can someone advise where this sensor is and what it looks like.....?

Thanks

david s poole · #2 03-05-2007, 02:10 PM

car is almost certainly short on fuel mixture.adjust 3mm[between fuel dist and plate] in clockwise direction in small increments[1/16th turn or less]

zcc · #3 03-05-2007, 04:11 PM

I did what you did including changing the EHA and it does the same on the cold starting except that it remains rough for few seconds only. What shall I do david s poole?

JFawcett · #4 03-05-2007, 06:02 PM

Understand this is a fairly touchy adjustment - what exactly am I trying to do here? Just adjust the throttle until it smooths out or what?
Understand it doesn't matter if hot or cold when adjust......

just-n-time · #5 03-06-2007, 10:36 PM

Quote:

Originally Posted by JFawcett

Understand this is a fairly touchy adjustment - what exactly am I trying to do here? Just adjust the throttle until it smooths out or what?
Understand it doesn't matter if hot or cold when adjust......

Yes this is a sensitive area, use caution when you make the fuel adjustment,as Dave said make small moves with the Allen wrench.it will take a few seconds for each turn to set up,you will find a spot that makes the Eng. comfortable,but go slowly. When you replace an EHA you will need to balance the fuel system.Good luck let us know how you are doing.JNT

just-n-time · #6 03-09-2007, 11:05 PM

Quote:

Originally Posted by zcc

I did what you did including changing the EHA and it does the same on the cold starting except that it remains rough for few seconds only. What shall I do david s poole?

The EHA why was it changed? If you did not have it set or the fuel would not flow?Any how you need to set the EHA by building a harness to put between the EHA and the plug.The wire farthest from you needs to be linked direct to the harness the wire closest to you needs to have a two peace wire so you can run a meter in-line. Once you have set the meter in to the line you will be setting the meter to read ma.start the car and read the meter.The correct reading should be between -0ma to +0ma get as close to that setting as possible, I had to take my EHA off 4 times to finally get that reading. NOW A WORD OF WARNING,on the inside of the EHA is a brass screw remove it PLOW ALL THE FUEL OUT OF THE HOLE, You Will the see a allen screw it is 2.5mm,it has no NO resistance to it plowing out the fuel will allow you to see the orientation of said screw, place tool into it and turn it 1/8th turn, make a note of direction of turn,reassemble and test current,If you got closer to the goal,then do it again until you arrive at the desired goal.NEXT word of WARNING,each time you reset the EHA you must rebalance the fuel mix with the 3mm allen wrench.LOOK UP www.landiss.com/mixture.htm

cool · #7 03-10-2007, 10:40 PM

The only way to adjust the fuel mixture is thru an aide of a CO tester, (No other precise scientific way of doing it) I assure you that other proceedures are mere guessing game.

zcc · #8 03-11-2007, 08:40 AM

Quote:

Originally Posted by cool

The only way to adjust the fuel mixture is thru an aide of a CO tester, (No other precise scientific way of doing it) I assure you that other proceedures are mere guessing game.

What is an CO tester???