Hello everyone,

I'm am going nuts on this car and I would greatly appreciate all the help I can get!

It's a 1991 300E-24 with only 85,000km on it.
The engine is the 3.0L 24valve, 104 980 model, (wasn't for sale in North America)

It has:

- Excellent Compression
- Top Oil pressure
- The head gasket was replaced (due to it leaking oil on the right side)
- The head, valves, lifters, etc were all flawless..
- Intake gasket, and ALL seals, gaskets, etc. were replaced on the engine and related components.

Brand New Genuine Mercedes Parts
(Or Bosch of course where needed)
Installed are:
- ALL Temp. sensors
- Over Voltage Sensor
- ALL Injectors
- Both Fuel Pumps and Filter
- O2 Sensor
- Intake Temp. Sensor
- Electrohydraulic actuator (EHA)
- Cam position sensor
- Pressure Regulator
- Plugs, Wires, Cap, Rotor
- ALL Rubber hoses to the head and CIS-E
- Fan Clutch

PROBLEMS------------------------------------

FIRST----

COLD... It starts and runs like a dream, drives perfect, in gear, in park, etc.

BUT

as soon as its been run for at least 30-40 minutes (by the way its cold outside here now) it will start to SURGE up and down.

As long as I DON'T shut the car off OR put it in gear it will manage for about 90% of the time to stay running...

IF I shut the Car off in this state IT WILL NOT START again just by turning the key, I have to turn it over many times and put the pedal right to the floor and MOST TIMES It just ends up flooding out.

IF I drive the car from cold and keep my foot on the brake at lights and keep it at least 1000 rpm or a bit higher it will not surge or cause any problems, driving along at ANY Speed its fine.

SECOND-------

Dispite the fact that it has a New O2 sensor and Overvoltage relay
the Oxygen Sensor Failure light Stays ON ALL THE TIME.


THANKS-A-MILLION IN ADVANCE TO ANYONE THAT CAN HELP!!!

Best Regards,
David

 

I doubt this could be it...but have you checked the voltage regulator on the alternator? Is the only code it is pulling is the O2 sensor?

 

No I didn't check the voltage regulator,

I didn't think that it could be related to the problem.

I have Snap-on MT2500 with the Mercedes Cartridge thru to 08' with all the adapters but It seemed to me that the info you could pull from these cars with a scanner is limited,

How do you pull the codes on these cars?

 

Engine you have was for sale in the USA.
It's the interim DOHC engine with the KE-Jetronic III and distributor
Used prior to the intro of the HFM injection and spark coil DOHC.

New O2 sensor or connection can be bad?
Idle control valve not functioning?

The most common item that you haven't replaced is the OVP...this can create the hard start condition you describe and a whole bunch of other anomalies !!!

Ps2cho suggested checking the voltage regulator.
The KE-Jetronic III is very sensitive to low voltage which causes many gremilins.

I'd start with a fully charged battery.
See if the OVP fuse is in tact and the relay functioning.

From there recheck the O2 and check the ICV.

All logic goes via the OVP.

 

I mis-typed it in the list then...
Over Voltage Sensor
I guess I mean then the: Overvoltage Protection...

It has two 10AMP fuses on top and is brand new...

I'll check the voltage regulator.......

as for the O2, does the OVP supply the ground or power to the O2 indicator or does it always have the power there and the ECM send a ground to the Light?

I HAD put a O2 senor in not long ago and this is the second one now, just incase it was faulty...

 

O2 goes to the KE control module.
Signal from the O2 controls the fuel mixture.
So no ground with the OVP.

Erratic or inability to idle can be the idle control valve.
The ICV is wired between pin 87L of the OVP and pin 3 of the KE control unit.

 

Update:

If I allow air to "Bypass" the AIR FLOW VALVE then the engine run and starts perfect when its fully warmed.

I have a new one coming in from Mercedes in the morning, I'll keep this updated.

Regards,
David

 

Might be the EHA valve and the idle control valve. Check the duty cycle when cold and warm.

 

EHV ?

Is that the purge/control valve for the EGR?

 

Well I changed the idle control valve and the OVP relay (again)
and now it seem to run fine BUT the O2 sensor failure light is still on dispite all that I've changed, even the new O2!

Any ideas??????

Thanks!!!!!!