hello all im new to this forum im having a problem i just had an emmisions problems ihad hi hc and hi nox so i changed the egr and th o2 sensor cause it was not switching now i reset the pcm and at 212 degrees it still stays in open loop any suggestions would be most greatful

thanks
conrad

There are two different areas of operation, OPEN LOOP and CLOSED LOOP.

During OPEN LOOP modes the PCM receives input signals and responds according to preset PCM programming. Inputs from the upstream and downstream heated oxygen sensors are not monitored during OPEN LOOP modes, except for heated oxygen sensor diagnostics (they are checked for shorted conditions at all times)

During CLOSED LOOP modes the PCM monitors the inputs from the upstream and downstream heated oxygen sensors. The upstream heated oxygen sensor input tells the PCM if the calculated injector pulse width resulted in the ideal air-fuel ratio of 14.7 to one. By monitoring the exhaust oxygen content through the upstream heated oxygen sensor, the PCM can fine tune injector pulse width. Fine tuning injector pulse width allows the PCM to achieve optimum fuel economy combined with low emissions.

For the PCM to enter CLOSED LOOP operation, the following must occur:

Engine coolant temperature must be over 35°F.
If the coolant is over 35° the PCM will wait 44 seconds.
If the coolant is over 50°F the PCM will wait 38 seconds.
If the coolant is over 167°F the PCM will wait 11 seconds.
For other temperatures the PCM will interpolate the correct waiting time.
O2 sensor must read either greater than 0.745 volts or less than 0.1 volt.
The multi-port fuel injection systems has the following modes of operation:
Ignition switch ON (Zero RPM)
Engine start-up
Engine warm-up
Cruise
Idle
Acceleration
Deceleration
Wide Open Throttle
Ignition switch OFF
The engine start-up (crank), engine warm-up, deceleration with fuel shutoff and wide open throttle modes are OPEN LOOP modes. Under most operating conditions, the acceleration, deceleration (with A/C on), idle and cruise modes, with the engine at operating temperature are CLOSED LOOP modes.

thanks for the reply what if your at operating tempature and your still in open loop i had a code on my scanner snap-on mt2500 that said o2 was not swiching so i changed it disconnec\ted the battery to reset the codes and it wasnt there anymore but every thing else on my scanner looks fine tps is good ect is good o2 is good it says its switching from lean center rich but it still stays in open loop

aahhh the only thing i didnt try was idle it with the a/c on

if your o2 sensor is switching, your ect is 212 or so and your still in open loop, there is only 1 thing left the pcm

i dont think a snap-on scaner shows open or closed loop on a chrysler like it does on a gm