Like everything else on this car, nothing ever messes up reliably enough to diagnose, it's sporadic.

But here's what it does: every once in a while (by that, I mean that it only does it for about two minutes or less - about every four or five weeks. Nothing predictable about it). It will just randomly start speeding up and slowing down... everything electrical seems to be affected. My radio and climate control don't care, but all the gauges on the dash go nuts. Oil Pressure especially. Bounces like a pogo stick. During these times, the RPMS fluctuate between 1200 and 500 - it nearly dies but catches itself. At 1200 it's enough to propel itself through a parking lot even when I'd rather be able to sit there at a non-moving idle. I have to stand on the brakes while it does it (or put it in Park, which is hard if I need to keep moving). After a minute or two, things stabilize. My radio and such are completely unaffected but the gauges (and the engine) are very confused.

I have not yet tested with a voltmeter to see what's going on. I don't always carry it with me. Last time I stuck it down in the cigarette lighter, I hit a bump I wasn't expecting and shorted that fuse out... so I'll have to make a pigtail on one of my old phone chargers or something and use alligator clips to secure the meter to that and just watch it while I drive, I guess. Any first thoughts?

Also, sometimes, when I crank it up on a cold (or warm) day, it idles normally. As soon as I hit the accelerator though, it hits a fast idle (1000 rpm) and just won't go down until it's ready to.

The ELR device up by the windshield works perfectly, as far as I can see. It holds a perfect 630 or 670 or whatever is recommended by the FSM for our engine, at position 4, and varies the rpm by 20 rpm increments at all positions on the switch, just like it's supposed to.

Thanks, for any ideas.

__________________


~Michael S.~
Past cars:

1986 300SDL
1987 300SDL
1982 240D
1982 300SD


Current:

1987 300SDL

on the back of the IP OK?

__________________
1987 300D (230,000 mi on a #14 head-watching the temp gauge and keeping the ghost in the machine)
Raleigh NC - Home of deep fried sushi!

How do I identify it?

Also, if it's relevant, the stop lever tends to move up and down on its own half the time. Unrelated to the other events as far as I know, but it might be a common symptom or something.

__________________


~Michael S.~
Past cars:

1986 300SDL
1987 300SDL
1982 240D
1982 300SD


Current:

1987 300SDL

Do a search on "overvoltage protection relay".

Every so often this device rears its ugly head and offers up some symptoms that are random and not clearly understandable.

See what you find and report back if you decide to change it.

~2" round piece on the back with a two contact wire plugged into the top.
I'm still looking for the test procedure in the FSM and will post it.

Stop lever movement may indicate a vacuum leak, fwiw.

__________________
1987 300D (230,000 mi on a #14 head-watching the temp gauge and keeping the ghost in the machine)
Raleigh NC - Home of deep fried sushi!

You can forget about all the interest in the ELR system. If the actuator was the issue, the idle would be affected but the remainder of the electrical system would function normally.

I just did the search and got 9 pages .... might be a while.

__________________
1987 300D (230,000 mi on a #14 head-watching the temp gauge and keeping the ghost in the machine)
Raleigh NC - Home of deep fried sushi!