O2 sensor experts, chime in

[metroplex]

Does it matter that my heated O2 sensors take 5 minutes to heat up properly and start voltage transitions after a cold start? Even though it takes about 5 minutes for it to do so, it is reporting proper fuel trims (+/- 1%) while it is waiting.

The question is: Do I want to spend another $120 on the right O2 sensors or can I keep running my Bosch O2 sensors?

Here is a run I just logged 5 minutes ago:

Here was the run from yesterday:

Here is a run from the E-250 with the same OE o2 sensors as the Vic (DY-850):

Granted, I did not log open loop conditions for the E-250, but assuming it's based on a similar tune to the Vic, it should transition to closed loop within 40-70 seconds.

According to the Ford PCED ref values, the O2 sensors shall switch normally when in closed loop mode. So as far as I can tell, the E-250's O2 sensors start switching normally right after the transition into closed loop mode.

This is NOT the case with the Bosch 15717 O2 sensors. I am going to install DY-850s on the Vic and see if this changes. Even thought the fuel trims look normal with the Bosch sensors, it should heat up and transition within 50 seconds. A delay of 5 minutes is not normal and would probably yield low fuel economy.

 

[brianl703]

The fuel trims it's reporting while the oxygen sensors are warming up are from memory.

 

[metroplex]

Does that include short term?

 

[chenobylite]

5 minutes isn't so bad. As long as the amplitude swings are within spec (yours are) and the cross counts are more than 8/second the sensor is good. Worry more about laziness in amplitude or cross counting than a bit longer warm up time. The H2OS is there not only to decrease warm up but also to prevent falling out of closed loop at idle when exhaust temps droop.

Your fuel economy won't be up to snuff anyway during the 5 minutes after a cold start due to the water sensor, even in closed loop. Oh and fwiw, Bosch invented the lambda sensor in the first place so I wouldn't sweat using theirs.

 

[GenesToy]

Would like to see the waveforms of the dy-850 motorcraft sensors? Maybe the Bosch sensors have a smaller heater and it takes a little longer to reach operational performance. Good Luck Metroplex

 

[robbobster]

FWIW -
My heavily modded Expedition runs much better with Bosch O2 sensors.

We had a hard time getting the tune correct with Ford factory sensors.

So I don't htink you should worry about using the Bosch units.

 

[metroplex]

The Bosch O2 sensors are taking roughly 300 seconds to start switching properly, and this is even with a hot restart (ECT at 180F).

The E-250's DY-850 OEM sensors start switching right when the van goes into closed loop - as per Ford spec.

 

[wiswind]

One of the things that the PCM is monitoring is the switching times of the Oxygen sensors....
So if they get too far out of spec.....you will get the CEL.

I did a fair amount of reading on oxygen sensors...so I am only repeating what I have read. The PCM also monitors and has codes for the heater circuit. If you look up the OBDII codes...you will find that they have the Oxygen sensors pretty well covered.

It is normal for an oxygen sensor to slow down in switching rates as it ages. For that reason, in a 2 bank system (total of 4 oxygen sensors, 1 before and 1 after EACH catalytic converter) I would replace both upstream (before the converter) sensors as a pair. This will keep both banks with the same switching charactoristics. I would also stay with the same manufacturer and part number in both banks.

 

[metroplex]

Funny thing is that I have never gotten a MIL/CEL/DTC ever even when the cats were practically on fire.

 

[GenesToy]

Have you checked your heater voltage and grounds when vehicle is started. Seem slow to heat up to start having a effect. Don't remember what Ford vehicle it was but had too replace both front oxygen sensors per tsb as it caused a slight hesitation in first minutes because computer was commanding closed loop and sensors were not ready to react fast enough. No codes. Changed sensors to number per tsb and problem was resolved. They were to slow to heat up.