hi everyone,

i have a 1991 2.3 8v 190e with an automatic, i recently changed the plugs, air filter, cap and rotor...

ive been trying to adjust the air fuel mixture, the previous owner said that it needed to be tuned a little bit because it was running rough at idle. i replaced various hoses that led into the ICV, to manifold and valve cover which did help stabilize the idle. but the idle still is still kind of rough, and when it is put into Drive, the rpms drop to about 550-750 and the motor seems like its going to die. the rpm at idle/park is about 1000.

i have a multimeter that reads duty cycles. i followed the procedures in the shop manual, which includes pressing the buttons on the X92 connector to get it into the "on/off ratio output" (constant light, no blinking and the check light is not on).

so at idle, it is reading a constant 89.9% duty cycle. in the shop manual, it says at idle it should be at 50+/-10%, but if i turn the mixture clockwise, or counterclockwise, the duty cycle at idle is the same. if i rev the motor up, it will move around though.

so my question is, at idle, should the duty cycle move around when i change the air fuel mixture? if it is not moving, would that indicate a fouled oxygen sensor?

thanks in advance!

Things I did to vastly improve my idle to super smooth from very rough:

#1. Replace all vacuum hoses, elbows. and connectors.
#2. Replace 02 Sensor if you haven't. Was most critical for me.
#3. Replace water temp sensor/air intake temp sensor (if you have one).
#4. Go to Autozone and get some $1.99 Autolite Copper plugs and install.
#5. Replace OVP if you haven't already or test with a known good one.
#5. Check the hoses going to and from the Idle Air Control Valve. One of
mine was cracked and causing most of the rough idle I later figured.
#6. Clean your Idle Air Control Valve out and make sure it's clicking when
you start your car by leaving it up on top and turning key on and off.
Should be able to hear it operate and clank one way or the other.
#7. Change out plug wires, rotor, distributor cap, and coil.

After I did that, I adjusted my air/idle mixture CCW a quarter of a turn (wait about 30 seconds after you do it each time for computer to adjust) until it started gaging a little and then I backed it up 1/8 th. I would also put my car in drive, put on emergency brake, and adjust air/mixture, until it idled best it could. Last night, I just put in a new fuel accumulator to help the starts and so far ithas started on first crank like a new car would.

Hope that helps.

Steve