Idle Issue with my 1986 300SDL: Help
 

Hello!

I have searched the archives but couldn't find helpful info.

I am having issue with my SDL idling erratically. Here is the problem:

1. Black smoke (light) at tailpipe

2. Tachometer jumps like crazy

3. At stop lights, car tend to shake and surges as if it wants to jump forward

Here is what I did:

Checked OVP, 10amp fuse is ok - no crack
Checked EDS - disconnect and sprayed electronic contact cleaner, replaced with spare EDS - same issue
Checked fuses - all clean as new

What could be the problem? Car starts and can be driven, but I don't like the shaking...

Thanks

How does it idle if you disconnect EDS, or at least the ELR actuator at the tail end of the IP? You might have to help it idle by leaning on the throttle linkage so it can sustain idle. What I'm interested in is whether it idles smoothly without EDS. My guess at this time is a bad ring gear sensor or bad wiring between the ring gear sensor and EDS.

Sixto
87 300D

Thanks Sixto! The only brave one to the rescue, while others don't even bother to offer a hint...

I decided to take an adventure searching for the problem.

Disconnect EDS - no problem. Engine keep running and shaking.
Replace with spare EDS. Same...
Plug brand new OVP. Same issue Hmmmmm....
Disconnect the connector to the red thing on the head of the IP. No change..
Jerked the wiring harness (male and female) that leads to the head of IP, noticed a reaction. Tried again and found that on the female connector, there are two wires (brown and white) soldered to each pin. The white wire broke off from the pin. (Very hard to notice).

Borrowed a solder gun from a friend and soldered the wire to the pin.

Problem solved. Happy camper...:)

Lesson learned:

The harness insulator can become brittle a crack due to hot temp in the engine bay. Engine vibration can break the pin connectors over time.

Thanks....

I am still looking for a SDL radiator. If you have a spare, please PM me.