Expert: Sean Halliday - 10/7/2009

Question
QUESTION: Just swapped E16I engine with same engine and year, but had 3 wire O2 sensor. ECM Mode 1 shows no led, green or red. Mode 2 shows no rich/lean activity. O2 sensor is heated 3 wire, although chassis is wired for 1 wire sensor. Hooked wiring harness connection to center wire of 3 wire sensor, eliminating the heater. Removed battery for 25 hours to try to reset ECM, but still open looped. Can I force it to closed loop?

ANSWER: The o2 senors would not be different as they are on the exhaust.They were on your original exhaust so you have put the engine in with the wrong wiring.The engine you got has the wrong loom and thats why it will not work with your sensors.Why didnt you swop your old loom from the old engine?This will solve your problem.It will work if you have the proper engine.

---------- FOLLOW-UP ----------

QUESTION: I am using the heated O2 sensor as a non-heated sensor. The harness that was on other car was cut, I got the engine without a good harness. The only difference is the heated VS non-heated O2 sensor. When does the ECM go to closed-loop? If an O2 sensor fault puts the ECM in open-loop, how and when will it again try closed=loop? What forces it into open-loop mode? O2 sensor only? I'm sorry for my confusion. I understand what you were saying, use right harness, but maybe a better answer would be use correct O2 sensor for harness, I.e. non-heated O2 sensor. The answer is the threads on the single wire is larger the the three wire sensor. The threaded fitting in the manifolds are both corroded in place and I couldn't find a thin wall socket to try to get them out. I could swap exhaust manifolds and then be OK, but I suggest that it would still be in open-loop mode. I appreciate that you took the time to respond, I just don't think we are understanding each other. Please accept my apologies if you think I am wrong.
Thanks,

Patrick

Answer
Closed loop is when the engine is at normal operating temp,open loop is when the car is cold.The ecm will not operate without the proper senosr as the heated o2 sensors cannot heat as there are no wires for them.You have 2 choices,get the right loom for the chasis,get  the exhaust system for the engine/wiring you fitted.You will not "force" the ecm to close without the right sensors.