300Te running rich

penguin

New Member
Joined
Sep 30, 2003
Messages
8
Location
Cardiff
Car
300TE
my 1989 300TE auto has started to run very rich when warmed up. I'm new to Mercs, what should I check first? The air filter and plugs were changed about 6 wweks ago. Help Please
 

Shude

Hardcore MB Enthusiast
Joined
Jun 1, 2002
Messages
13,882
Location
Cheshire
Car
CLK55 AMG
can't offer any specific help except to say this should be in the engine section of the forum...moving! :)
 

canada911

New Member
Joined
Oct 13, 2003
Messages
12
Location
Montreal, Québec
Car
190e 2.3-16vlv
I think you have a X11 or a port with a couple of pin where you can check your lambda? Did you check what your lambda was? Did you tried to readjust it with the mixture key (if there is any)

Sorry, but I'm not really familar to 300
 
OP
OP
P

penguin

New Member
Joined
Sep 30, 2003
Messages
8
Location
Cardiff
Car
300TE
I was going to adjust mixture, but a friend said not to do this without an exhaust gas analyser attached. I'm going to try and get this done tomorrow. BTW I was checking connections to various sensors etc and found a partly broken wire leading to a blue 2 pin connector in between 2 injectors, after reconnecting it car ran richer than ever!
 

canada911

New Member
Joined
Oct 13, 2003
Messages
12
Location
Montreal, Québec
Car
190e 2.3-16vlv
Why a gaz analyzer if the lamda do the thing, what is your lambda reading?

Is those 2 pin wire for the idle speed valve??
 

babybenz

New Member
Joined
Jun 12, 2003
Messages
4
BTW I was checking connections to various sensors etc and found a partly broken wire leading to a blue 2 pin connector in between 2 injectors, after reconnecting it car ran richer than ever!

That would be your coldstart valve.I think your CIS-EZL coolant temp sensor may be faulty, causing the coldstart valve to be operated even after the car is warm.You can check resistance values at the sensor to confirm this.When cold you should see very high resistance in the kilo-ohm region and then when warm, say 80 deg (abt 300 ohms in my car).

It it is faulty,that was probably why it was disconnected.I don't know if the coldstart valve is leaking but you should check it just to be sure.

Then, with the coldstart valve disconnected, the car would experience hard coldstarts.In order to mask this problem, the mixture was probably richened.

If the coldstart valve is indeed leaking, it would cause the car to run richer than normal and coldstarts would be no problem even with the electrical connector disconnected.

Check out these 2 components, then, when sorted out, you can tune the mixture by duty cycle at pin 3 of X11 connector on the left fender in the engine bay.

My 2 cents.

Cheers.
 
OP
OP
P

penguin

New Member
Joined
Sep 30, 2003
Messages
8
Location
Cardiff
Car
300TE
Many thanks for the help.

It was the coolant temp sensor at fault, and a previous owner had richened the mixture to compensate. with both of these fixed seems to be running fine.

Starts brilliantly first thing in the morning now and following drivers don't have to drive through clouds of my black smoke.


Thanks again
 

Users who are viewing this thread

Top Bottom