manoa

Aloha,
I have a 94 e320 that is currently undriveable. I bought the thing as is (with electrical problems) for 500 bucks + back taxes. Changed the engine wiring harness because it was totally deteriorated, but problems still exist.

The engine responds to the accelerator pedal only in P. It actually revs up great in P. When I switch to D or R, its like a totally different car- won't respond to accelerator/limp mode, plus it has an uneven idle. I changed the throttle actuator, too. That didn't fix anything..... The battery is bad. I've been jumping it to move it. But all accessories work after jumping it.

I believe there are multiple problems here, but hoping to get the major ones licked first. I don't have money to throw at this thing so pinpointing the problem is crucial. The thing is in beautiful shape, so it'd be a shame to part it out. Can anyone help me diagnose the problem?
Mahalo,
manoa

ptoro01

I'm going to assume that it revs in P, but not that great. Based on that assumption, I'd say you have a misfire.

Read your spark plugs.
Based on that, you'll know if you have a weak spark, too much fuel, or not enough air.

Check for vacuum leaks.
Read check engine codes.
And report back.

Floobydust

Aloha manoa -

I agree that you probably have a misfire - the engine will rev under no load, but bogs when a load is applied. From the sound of it, it seems like a multi-cylinder misfire as well, so I would check the part of the harness the connects to the ignition as well as the plug wires themselves. MB uses a wasted park type ignition system on the M104, so one bad connection will affect two cylinders.

You should also double check all of the various harness connectors to make sure they are fully and properly engaged.

If you find nothing there, you will probably need to start reading the diagnostic codes form the ECU to track things down further. It is possible that the old harness damaged the ECU (coil drivers, injector drivers). If it did, this will show up in the codes.

- FD

ps - Are you indeed up by Punchbowl?

manoa

Thanks for the replies. I'll check the plugs, wires, vacuum etc this weekend.
Unfortunately, I don't have a code reader yet.

It's actually revving pretty strong in Park- strong up to 4500, no more, then bounce down to 4000. But no power in Drive. Which makes me me think its an electrical problem. But this is my first MB- I'm used to working on simple old trucks.

I hope the rest of the wiring doesn't look like the old engine harness did. It's very possible that the ECU was damaged. The wire casing was like dust.

.....And yes, not far from punchbowl
Thanks again, I'll let you know what I find by Sunday

manoa

Updates
The engine is definitely not firing on two cylinders. I think it is because of a faulty engine wiring harness - EWH (the one I replaced). The wires and coil drivers? seem fine. I replaced the spark plugs.
When I unplug two of the three EWH-to-coil connectors (one at a time), there is clearly a loss of power. Unplugging the third, there is no difference. I shuffled the coils to make sure that wasn't the issue. Also shuffled wires, they all work.
So this is why I think it's my new wiring harness. I hope it isn't- the thing wasn't cheap. Any other possibilities that could save me from buying another one?

Separately, there is now NO power in park or drive. Accompanied by the ASR light. Something seems to have shorted out/old wires. Do I need a new throttle actuator, too?

Hope this is clear enough.
Thanks for your help.
Aloha

ptoro01

Check the connector itself, there's a piece of metal in there, maybe it's twisted or missing?

The throttle body harness does fall apart too, check if yours was replaced by cutting into the cover.

You can check continuity in the harness. It might just be pinched somewhere?

Does it have a weak spark or no spark?

After that, it's the ecu. Does your car have traction control? In that case, it might be the throttle intake.

Edit: The asr might be kicking in, cutting the cylinders out. Check the throttle body harness.

neanderthal

I had what sounds like the same problem. I couldn't figure it out too. All new plugs. Bought a coil to replaces the one that seemed like it wasn't firing. No change. Swapped it around with another one. No change.
But it was clear that 2 connected cylinders (same coil) were not firing.

I eventually took it to my mechanic and he said it was something in the vacuum pipes. Didn't specify beyond that even when I asked.

cds07710

HELP:

I just replaced my old wiring in e320 1995 (was falling apart for the biodegradable reason)
I need help: In front of the car there are 3 connectors coming from harness to the vacuum manifold- located right across from radiator's ventilator Actually with ground there are 4 connectors coming from new harness into my car; I omitted to identify these 3 connectors, and all of them are identical. One cable coming from the main harness is indeed black but with a white line. this is the only visible difference among the 3 cable connectors.
Please, let me know how I pair them, as I experience malfunction on the engine, and I feel guilty about these possible mismatch

I greatly appreciate your help
Thank you in advance
Daniel

cds07710

The harness I have/replaced is 1244402933
Everything matched very well but I did not pay attention into the front 3-connection