2007 H3 I5. Before and after a canister vent valve repair I noticed on my scan tool that it was running open loop. Drove it 5 miles or so and stayed that way. Runs great. No codes. Assuming my scan tool is telling me the truth can anyone provide insight on what might cause an open loop especially with no codes? Assuming this thing has heated o2 sensors I would think it would go closed loop in under a minute.

 

a crap aftermarket temp sensor (probably made by standard motor) that is off by a few degrees between air intake temp and coolant temp? ECU never sees the correct temp to close the loop. thinks it is still cold. there is also a mod they used to do with a resistor on the temp sensor line to trick it to stay in open loop for more fuel delivery.

 

I'll check those things out. I appreciate it!

 

Bad T Stat? Bad O2 Sensor? Bad connection in harness/connectors to those....

Crappy Azzed OEM Battery Terminal Connectors not replaced with quality aftermarket set like Stingers or your favorite brand?

 

The tstat and o2 sensor should throw a code though.

 

Drove it today and watched the temp rise on my scanner from 71F to 190F. Stayed around 190 the whole time. O2 sensor harness didn't appear tampered with.

 

i ask again. what about the intake vs engine coolant temperatures. do they correlate when both are cold with no start or are they off from each other by 14 degrees or more?

 

Not always, depends upon the exact problem. Incorrect voltage due to poor connections may be enough that the PCM thinks they are working, but the voltage is far enough off that the reading is inaccurate.

 

They were within 4F initially but the IAT goes up slowly I assume because the MAF heats up. Drops back to ambient air temp when started.

 

Could be. However the engine temp looks normal and the o2 sensor waveform looks good.