[mamato5]

Car won't pass emissions test. Got code 44. Smog pump is good. Bypass and diverter valves are operational (they switch properly when vacuum is applied/missing). Vacuum present at both valves. Pipes to heads/cats are clear.

My questions are:
1. under what conditions will the EEC command a bypass?
2. under what conditions will the EEC divert air to the heads?
3. under what conditions will the EEC divert air to the cats?
4. and finally, how does the EEC know that this system is not functioning?

Thanks in advance for any assistance.

[muck89s10]

code 44 Thermactor OBD2
Your dealing with the wrong circuit. Its the O2 sensor
Troublcodes.net Trouble Codes OBD & OBD2 Trouble Codes and Technical info & Tool Store. By BAT Auto Technical

[spdjnky_42]

Unless this cars smokes really bad. You probably just need to do a full tune up and replace the o2 sensors.

[lxarlo]

Originally Posted by mamato5

Car won't pass emissions test. Got code 44. Smog pump is good. Bypass and diverter valves are operational (they switch properly when vacuum is applied/missing). Vacuum present at both valves. Pipes to heads/cats are clear.

My questions are:
1. under what conditions will the EEC command a bypass?
2. under what conditions will the EEC divert air to the heads?
3. under what conditions will the EEC divert air to the cats?
4. and finally, how does the EEC know that this system is not functioning?

Thanks in advance for any assistance.

1. The EEC will command a bypass in closed loop @ heavy engine load
2. EEC will divert air to the heads on a cold start/startup in open loop so the cats can warm up faster by continuing the burn of unburned fuel on the enriched cold start program.
3. EEC diverts air to cats on closed loop cruise.
4. EEC can not read downstream air pump flow, but upstream it uses the o2 sensor voltages to determine if they are working at the proper time. the processor knows when the o2 voltages are going to change, and if they dont do so accordingly, then it sets a code.