Onash

The new 95 E320 cab with the 104 engine seems to have a hesitation at 3500 rpm when accelerating. Knowing that this isn't a blistering fast car, the power dips at 3500 rpm but then picks up nicely beyond that to redline.

The 104 is DOHC engine. does it have variable timing/valving?

I also notice a bit of a vibration at idle - could be bad engine mounts or the same cause of the hiccup at 3500.

Any ideas?

TIA
Omar.

RBYCC

You should have zero vibration at idle.
It can be anything from engine settings to motor mounts.
Motor mounts would be more noticeable if you slowly rev the engine in park from idle.
If the engine smooths out when you do this then my guess would be engine idle settings.

The M104-24V has an "on-off" cam timing but around 3250-3500 rpm you have the addition of a variable intake flap which when it operates can give a feeling of slight hesitation and then power surge.
This is noticeable and normal unless you have a severe hesitation

Onash

It is definitely noticeable at 3500 rpm. I'd say it is severe enough to warrant investigation.

I think my next step is to change plugs, wires, and maybe even the coils.

Aside from those, and maybe cleaning the MAF, any other suggestions?

Thanks

RBYCC

Your "next step" can be quite expensive and not resolve your problem.

Let's start all over again with a single focus.
The only thing that happens at 3500RPM is the variable intake or resonance flap. It may also cause a slight rough idle.
If your read your codes that may help ( www.w124 performance.com/.../DTC_List_W124_M104.pdf )

Easy to locate and service, held on with four allen screws...check to see if it is operating properly.

Onash

Thanks for the diagram. Isn't that also where the Electronic Accelerator unit is? I know I have an issue with the ASR and the cruise control. The Owner's Bible mentions the EA as a cause for the ASR to come on and put the car into limp home mode (as I found out 100 miles from SLC at night and 39 deg temps on the maiden voyage home.)

Since I can live without cruise control till I get around to it, I haven't messed with it.

I'll report back what I find.

Thanks again
Omar

RBYCC

Electronic accelerator,cruise control, etc, could be the same/related problem...

Have you checked the condition of the wiring in the area of the intake assembly?
These cars had the bad wiring harnesses from the factory.
You may have to open up the harness to check for bare wires.

Check for vacuum leaks in the same area ?

Onash

RBYCC, Sorry for the delay in responding. I was finally able to put together a home made code reader and tested the car. I found the following:

On the self-test button on the connector (which matched up with PIN3), I got fault code 6 - Idle Speed Control Inoperable.

PIN 8 - one flash (No Malfunction)
PIN 14 - I got code 3 / 6 / 14.
3=EA/CC/ISC (M16/1)
6=Starter Lock Out/Back Up Lamp (S16/1) **note sure if this relates to my car.
14=Closed Throttle Position Contact Switch (S29/3)

Not sure what all this means yet. And I'm not sure what the code in parentheses means.

Any ideas?

Thanks in advance.

Omar.

PS I hope we all have a great New Year!!!

RBYCC

Code 3 probably is important based on your symptoms...Electronic accelerator/cruisecontrol/idle speed control module.

It may be fine but a bad harness will cause false codes and erratic operation.

The numbers in parentheses are the component designation as appears on the schematics.

First check the wiring as possible you still have the biodegrable engine harness.

Look for insulation breakdown on exposed wires but also peel back the harness wrap.

Onash

Sorry, I forgot to mention that the previous owner had the harness swapped out.

Is there a cleaning/maintenance/test procedure for the EA and the electronic throttle?

RBYCC

You have two devices..the M16/1 operator and the N4/1 control module.

This may help you to dismantle and clean:

http://www.google.com/url?sa=t&rct=j...55534169,d.dmQ