'86 SDL stalling - PeachParts Mercedes-Benz Forum

lowriderdog37 · #1 05-20-2008, 11:16 PM

When I let off the accelerator, my engine runs really rough for about a second when it gets down to idle, several times it has stalled. I noticed the mounts for the engine shocks on both sides are destroyed. Would this have anything to do with that?

sixto · #2 05-21-2008, 01:15 AM

Is the tach working? My guess is EDS isn't working or the signal isn't getting to that round plastic thing at the back of the IP.

Sixto
87 300D

lowriderdog37 · #3 05-21-2008, 01:28 AM

The tach is working fine. The engine feels like it's rpm is dipping, but the tach shows it only goes down and idles smoothly.

By round plastic thing, are you talking about the 3rd pic on this topic?

Help please, leaking fuel from IP

There has always been a small fuel leak from there, but I haven't been able to figure out what it is.

Just for reference...what is the EDS?

sixto · #4 05-21-2008, 10:45 AM

No, that's the control rod sensor connector. You have to replace an o-ring inside the IP to stop that leak.

What I'm talking about is most clearly seen in the first picture. The electrical connector into the round thing with a red plastic back between the IP and the cruise control actuator.

Sixto
87 300D

lowriderdog37 · #5 05-21-2008, 10:47 AM

And what is the EDS, so I can check that?

I checked the plastic thing on the back of the IP, I didn't see anything strange with it, but I don't know what it is, or where it goes. Anybody have information on it? Name, etc?

lowriderdog37 · #6 05-21-2008, 11:37 AM

OK, I have been doing a little searching around. I haven't found anybody else having the same problem like this on a 603, but several on a 617. Is this red plastic thing just an electronic version of the rack dampener pin? Anybody had any experience with this?

sixto · #7 05-23-2008, 10:25 PM

EDS controls idle rpm and emissions devices. It sends a signal to the red plastic thing behind the IP to stabilize idle. If you pull the connector at the red plastic thing with the engine idling, idle should drop to about 500 rpm. Might even stall.

To check EDS, change settings on the idle trim device by the master cylinder. Note the number on the knob next to the indicator. Pull up on the knob turn it so a different number is next to the indicator. Push back into place. The idle should change by about 50 rpm (or maybe 25 rpm) per numeric difference; e.g., changing from setting 5 to setting 2 should drop the rpm by 150 rpm (or maybe 75 rpm).

Sixto
87 300D

a2t · #8 05-23-2008, 10:41 PM

I'd check for vac leaks from tank to lift pump. Just plug off the soft line where fuel enters the engine bay from hard line, and draw vac on the line that went to lift pump. See if it holds 15 in Hg (you can do this with a simple hand held mity-vac). If no leaks, then check from hard line at engne back to tank (somehow). The engine sucks the fuel in so its all under vac to lift pump. From there, lift pump pushes fuel through heater, filter, and on to IP. Air bubbles cause this sort of grief and are usually easy to find (worn hose connection, hose clamp, ect..). Us WVO guys have this issue alot as we change routing so the ENTIRE set up is under vac all the way to IP. Any one of those connections can leak and let air bubbles in. The engine has tough time idling if too much air is in lines, as the IP really compresses the mixture.

Another way to test is to fill small cup with diesel and let lift pump draw directly from that. See if problem goes away.