M103 Idle/Sputter/Stall Intermittent Issue - PeachParts Mercedes-Benz Forum

JamesDean · #1 10-06-2015, 09:54 AM

Morning all,

I've started driving my 93 190E (m103 3.0) to work and the past two days have had some interesting problems.

My daily commute is 65 miles one way, all highway pretty much.

Monday:
-No issues once so ever until I got off the turnpike. I took my exit ramp and found that the car had randomly stalled out. Looked down at my tachometer and it was at 0. I was able to pop it into neutral and get it started back up on the off ramp without having to pull off or anything. After that all was fine, drive home was too.

I did notice that the idle felt a bit rough. It felt, to me, that it get progressively more rough and then the engine controls would rev the engine up a bit and it felt better. It would rev up to about 850 RPM and then slowly drop down to 700 or something like that.

Tuesday, on the way to the office:
-No issues once so ever until I got into stop and go traffic and had to idle for a while. The idle felt rough as it did the day before. It was not horrible, not like a diesel. It felt like a miss.

Traffic started to pick up and I gave it some throttle. The miss feel got stronger and it felt like I was not running on all cylinders. At best I could do about 2K rpm and 40 MPH no matter how much I mashed the pedal. Luckily I was at my off ramp and getting off.

I sat through two red light cycles hoping that it wouldn't stall out. Then the engine did the rough idle, and rev up thing and it drove like nothing at all happened.

Tuesday, on the way home:
-Engine stalled on offramp from 77 to turnpike, I was able to re-start without issue. No other issues until I got off the turnpike.
-I was driving down route 5 and I down shifted, sending engine RPMs up to 3500-4000 and the engine backfired. Loud pop, tachometer dropped to 0, I up shifted, and then tachometer restored to normal.

Experimenting at Home
Naturally, I've not been able to re-produce any of the problems. I did put my meter into the diagnostic port and it was reading 19-25% duty cycle at idle. IIRC this means its running quite rich. I did have a new catalytic converter installed over the weekend. I wonder if lambda needs to be adjusted?

I just got to work and am still investigating and thinking about causes.

Any thoughts?

I can tell you that the plugs, rotor, cap, and wires were replaced all within the last 10K miles.

I did have some exhaust work done, a catalytic converter and new magnaflow rear muffler were installed.

The motor has about 120-125K on it, chassis has 247K

Edit: Added more..