Based on all the information so far, I am planning to do the following:

1. Verify that a 95 E320 ECM adapats upto 32%, to get 7% more adaptaion than the current software limit. Find someone with a 95 E320 and figure out how to copy the Chip.

2. Replace the Diaphram pressure regulator.

3. Find out about the Purge switchover valve.

4. Have the Mercedes Benz dealer check for Intake air leaks.

5. Find a used speedometer cable (e-bay) to clean the EGR valve pipe.


From the Shell website, I found that the gasoline storage life is only about 6 months. After that it can cause problems. My car was not driven much from 94 to 03 (58K miles).

ECM controls the Air/fuel mixture by adjusting the fuel injection duration. I think that the ECM is opening the fuel injectors, but the injectors are not getting sufficient fuel flow, causing the lean condition.

Any suggestions to the above course of action?

__________________
Zafar
94 E320 58000 Miles

I had the Mercedes Benz dealership check the Fuel Pressure. This is what they found:

3.4 bar at Idle
4.1 when accelerating
Remove all vaccum from regulator diaphragm and pressure max's to 4.2 Bar.

Check for leak on Intake Manifold

Checked intake manifold for vac leaks, found no VAC leaks at intake or any vac hoses

Any idea's?

__________________
Zafar
94 E320 58000 Miles

For starters, I would run a good FI cleaner through it..
You may well have a gunked up injector [ as you mentioned long sitting]
The o2 sensor reads the leanest cylinder , so even just one screwed up injector can cause the ECU to get Lean message ..
I would also get the part # off the EGR valve to see if it has been change to the newer one.. there was a TSB on this for sticking valve...

Arthur, I read this at Alldata, Could the purge switch over valve cause the mixture to go lean?

COMPONENTS
The EVAP system consists of a non-vented fuel cap, vent valve (51), charcoal canister (77), purge switchover valve (Y58/1) and the routing hoses. The canister contains activated charcoal and a hose connects it to the throttle valve via the purge switchover valve.

OPERATION
When pressure in the fuel tank reaches 30 - 50 mbar (0.435 - 0.725 psi.) the vent valve opens allowing fuel vapors to flow from the fuel tank to the charcoal canister where they are absorbed.

With the engine running at a coolant temperature above 80°C (176°F) and a specific intake air mass range, the HFM-SFI control module (N3/4) applies a current to the purge switchover valve. The valve opens and vacuum from the intake manifold reaches the purge valve. Thus, the purge valve opens allowing fuel vapor from the charcoal canister to be drawn into the intake manifold via a port in the throttle plate.

In order to control the purge quantity, the HFM-SFI control module activates the switch-over valve at a frequency of 5,10 or 20 Hz (cycles) depending on engine load and other conditions . The purge quantity is determined by the duration of each cycle.

__________________
Zafar
94 E320 58000 Miles

<< >>

I mention that on the first page of these post..
The vave or any of the vac lines to it can cause lean condition.

To repeat.. I had a lean condition 104 that had a purge valve that was stuck in the open position.
These valves get gunk in them and stick..
A sign of a good one is to hold in in your hand and feel for a Heartbeat pulse...
It is on the left fenderwell and says 'MOT" on top.
Both the purge and egr can leak/stick and not show as vac leaks BC they are leaking within the system itself, as opposed to hissing / open to ambiant leaks..
I see you have AllData ... they have all these simple test procedures in there..

You will notice in the alldata info on purge that the ECU opens/closes the valve in little pulses.. [ that is the heartbeat feel I talk of]. The reason the ecu does this in little gulps is so that
the engine does not stall or run rough..it has time to absorb this
unmetered air in little shots, so you can see how a stuck open valve can upset A/F mix...
Usually, with both egr and purge, one will also get codes .. but not allways [ specially with intermittant sticking]
Some guys have success w/cleaning the valve with WD-40
[ archieves]

Arthur, I held the Purge valve in my hand and pulses were present. Does this mean that it is working properly or is it possible that it is partially stuck?

I hope that it is the purge valve, because the next items to check would probably be the fuel and air injectors.

PURPOSE
The air injection reactor system pumps air from a maintenance-free dry air filter mounted on the pump into the exhaust ports of the cylinder head to promote oxidation of CO and HC. The heat created by the oxidation process also brings the catalytic converter up to operating temperature more quickly.

OPERATION
Air Injection takes place for a about 110 seconds after start up and only when the coolant temperature is between 10 °C (50 °F) and 40 °C (104 °F), the engine speed is less than 3600 RPM, a specific intake air mass is not exceeded and the oxygen sensor is in open-loop.

Under these conditions the electromagnetic clutch of the air pump (125) is switched on by the HFM-SFI control module (N3/1). The HFM-SFI control module simultaneously powers the air injection switch-over valve (Y32) which provides vacuum to the air injection shut-off valve (126) in the pump circuit. Air is then pumped through the check valve (127) and into the exhaust ports of the #'s 3 and 4 cylinder in the cylinder head.

__________________
Zafar
94 E320 58000 Miles

The heartbeat test usually indicates an OK purge valve..

I would still run some injector cleaner through it before changing anything..

Arhtur,

I added 16 oz of Valvoline Fuel Injector cleaner, and 16 oz of Valvoline Fuel system cleaner to half a tank of gas and after a few hundered miles of spirited driving (at speeds which the public safety departments of most states would not consider prudent), when the fuel warning light came on, I checked the Codes and got the following:

Code 13.

I got a new code: Code 20 (Self adaptation at idle speed too rich or lean).

I added another 16 oz of Valvoline Fuel system cleaner and filled the gas tank with Shell Octane 93.

I will check the codes again after this gas tank empties. I have been paying very close attention to the Idle, although the RPM needle barley moves, a slight periodic vibration can be felt, which seems to have gotten better with the fuel system cleaner. An Inline six engine is inherently balanced and is one of the smoothest engines except a V12, without the use of a counter rotating balance shaft. That was one of the reasons I choose the E320 instead of 400E. I was not expecting to feel anything at all during idle.
With transmission in D, nothing can be felt at all. The RPM needle stays rock solid.

Checked engine oil, after 4500 miles, still looks new and the engine did not consume any oil. I am planning to change the oil at 5000 miles with Valvoline 10W30. What oil do you recommend?
At the 60K mile Z3 service, the Mercedes Benz dealer had used the oil mentioned above. I was considering either 10W30 or 10W40.

__________________
Zafar
94 E320 58000 Miles

I don't recommend any particular oil brand , as long as it 's Benz Spec.. I use Castrol GTX 10/40..
What I will recommend to you on the oil change is to do an archieves search that I posted way back on a TSB -re: oil level change on 104 eng.
They were having trouble with oil fill being too high and the TSB
changes the capacity [ I think it was about 1/2 qt less, but check for sure] ...

I would run this tank and maybe 1/2 of another w/o the FI cleaner and then change the oil, clear all codes [ write down what you have retrieved] and then watch for new ones

The reason I would clear the codes at oil change is you will then be assured of no gas contaminated oil [ which can bring on an Adapt trim limit code]]

At the same time . I would also do the trim memory reset procedure after you get the 1 Flash, no code OK ...
just to get back to Mean values

As far as idle is concerned , the 104 are famous for bad coil to plug connectors under the 3 coils ... if you have not done them, I recommend it , as they are short $$$ and most tech do them at plug change BC of their short life...[$7-8 ea]

The computer stops the injectors from opening when it detects a skip at the plugs, [ to protect the cat from getting raw fuel dumped into it],so these can also cause a lean reading back to the DM,,,
As you can see , all systems are related and affected , one way or another...

Mercedes dealer changed the coil to plug connectors. Service manager sketched the coils with the connectors and the bottom connector is the one which goes bad. Hopefully the Tech replaced the right ones, about $14 each and $20 labor. All three coils were done.

That idle condition seems to be better.

Since I was there, I had them change the oil as well, they had Mobile 15W40. Next oil change I will go back to 10W30.

I cleared all the codes, and checked them a few days later. Still getting code 13 (mixture too lean or rich).

What can be checked next. MB has added a layer of complexity for emissions controls. Some choices like delayed transmission shift can have adverse effect on a cold engine.

Again, it drives fine at all speeds, like a new vehicle.

Is it possible for the secondary air injectors to keep on running even after warmup, causing the lean mixture?

Some time back, after some hill climbing and decent, I had code 20 (mixture too lean or rich at idle or partial load) but that has not returned since. This was before the fuel injector cleaner, connector and oil change. Two other DM codes I had were code 3 (lambda inoperative) and code 4 (air injectors inoperator), along with 19.

Speedo needle vibrates a little below 40 MPH, can that have any effect?

__________________
Zafar
94 E320 58000 Miles

Replaced the ECM. Problem fixed.

__________________
Zafar
94 E320 58000 Miles