Another “surging” 1993 124CE

[bkaiser]

Hi Everybody,

I hate to add to the list, but my 197,000 mile 1993 300CE has developed a bad surge at idle to the point it want’s to stall in gear. I’ve owned it for about 22 years now and have done almost all the wrenching.

In the past (10/18) it developed a stall and just shutting off condition, which turned out to be the stoplight switch:

details W124 codes/stumbling/shutting off

June, 2023 it started dropping cylinders randomly at idle, but otherwise ran great.

Details: http://www.peachparts.com/shopforum/tech-help/420154-1993-300ce-dropping-cylinders-idle.html[/URL]

That turned out to be coil, plugs, wires, OVP and O2 sensor. Not sure what actually cured the problem

It has the updated harness, I’ve opened up the harness near the throttle body and injectors and everything looks fine and all the insulation colors are bright and flexible.

It sat most of the winter inside. First couple of days it drove fine. Just a slight unevenness at idle. Last week it started surging badly. Idles about 600-700 rpm but past that it runs fine. Cruise control work,

No CE light, 14 volts at idle. 80C temp but took a long time to warm up when it was colder. Oil pressure fluctuates at idle. It did start almost instantly cold or hot but now takes some cranking and acts like a flooded carburetor

CODES are with the button, non. With homemade code reader, socket #8 = 13 (02 sensor control system operating at rich or lean limit}
and socket #14 is 1.

I’ve lubricated the throttle linkage as that’s been a problem before,
Checked for vacuum leaks,
Used MAF cleaner which seamed to help a little

MAF was replaced at about 120K. EGR holds vacuum.

Vacuum at the manifold end of the EGR hose is only 10.5 HG.

Fuel Pressure regulator doesn’t small or weep any gas.

I wiggled the wires around O2 sensor which was replaced last year.

Any help would be appreciated. I’m stumped and discouraged. I had open heart surgery a couple f years ago and am afraid I’m not as sharp as I use to be figuring this stuff out.

I read through about 18 posts on surging and didn’t really find an applicable answer.

I bought a claimed updated Throttle body for $285 and insulation is just dust. I haven’t found anything like that on my car yet.

Thanks in advance