O2 Heater Questions

[briangsxr1000]

I have an 07 that's not heating up my sensors fast enough with LT headers which gives me a poor idle until the sensors get hot.
I've done A TON of diagnostics. Also replaced the PCM which made no difference. I have no codes.

The issue is the PCM is only commanding 50% duty cycle and that's typically what it would do to maintain temp, not increase it from cold.

Does anyone know how the PCM decides what duty cycle is appropriate for the PWM supply to the O2 heaters?

Does it look at coolant or cyl head temp? Does it always just run 100% DC on any startup until going into closed loop?

 

[biminiLX]

I’d expect this could be adjusted in the tune. Who is tuning it?
I’ve found the O2s fail rather quickly on bigger power and LTH.
Have you replaced them recently?
I’ve used Gen 1 Raptor sensors as they are the same sensor with longer wiring and heat wrap.
Good luck
-J

 

[briangsxr1000]

BJ is tuning the car. The time delay for closed loop is set for 60 seconds. Sensors are new NTK OEM sensors just with longer leads.

Problem is the PCM is not commanding 100% duty cycle when cold. I would expect to see 100% until warm and then the PCM would cut the PWM DC down to say 50% or less just to maintain heat at idle.

 

[Vinnie_B]

Engine coolant temp is key in pulse width modulating a resistance element of an oxygen sensor.


Pulse width modulating a resistance element of an oxygen sensor. The method quickly heats the resistance element of the oxygen sensor soon after start of the engine with a relatively high duty cycle yielding wide pulse widths. During a mid oxygen sensor temperature range, the method decreasing the duty cycle and thereby the pulse width modulation. And, upon the oxygen sensor reaching peak operating temperature range, the method decreases the pulse width modulated voltage signal supplied to the oxygen sensor to relatively short duty cycled pulses.

 

[briangsxr1000]

Engine coolant temp is key in pulse width modulating a resistance element of an oxygen sensor.


Pulse width modulating a resistance element of an oxygen sensor. The method quickly heats the resistance element of the oxygen sensor soon after start of the engine with a relatively high duty cycle yielding wide pulse widths. During a mid oxygen sensor temperature range, the method decreasing the duty cycle and thereby the pulse width modulation. And, upon the oxygen sensor reaching peak operating temperature range, the method decreases the pulse width modulated voltage signal supplied to the oxygen sensor to relatively short duty cycled pulses.




View attachment 1804084View attachment 1804083

I saw this and fully understand it but does it 100% pertain to the Fords? This seems t be a generic description.

 

[Vinnie_B]

I saw this and fully understand it but does it 100% pertain to the Fords? This seems t be a generic description.

I believe the concept applies to all. It protects the O2 from getting damaged. Why the PCM in your situation is only commanding 50% Duty cycle at cold start is the big question. Im sure coolant isnt the only input the PCM needs. RPM, Air,Fuel and spark come into play. I believe the issue at hand is in the Powertrain Control Hardware/Software or Engine Control Component. Did you try reflashing back to OEM and than reinstall your current tune?

 

[briangsxr1000]

I believe the concept applies to all. It protects the O2 from getting damaged. Why the PCM in your situation is only commanding 50% Duty cycle at cold start is the big question. Im sure coolant isnt the only input the PCM needs. RPM, Air,Fuel and spark come into play. I believe the issue at hand is in the Powertrain Control Hardware/Software or Engine Control Component. Did you try reflashing back to OEM and than reinstall your current tune?

I did try reflashing. I even replaced the pcm once. This is getting to be an expensive adventure.

 

[Vinnie_B]

The only other thing I can think of is going with another type of O2 sensor heater with less resistance. I'm just a low life auto electrician not a tuner....

 

[VNMOUS1]

NTK 22060
Try them

Sent from my SM-S918U using Tapatalk

 

[biminiLX]

Holley Dominator. Problem solved.

When you said new O2 sensor with longer wires do you mean extension harness? If so that could be an issue.
Otherwise I’d assume BJ has had some suggestions.
Good luck.
-J

 

[briangsxr1000]

NTK 22060
Try them

Sent from my SM-S918U using Tapatalk

I had brand new NTK 22106 which gave me long enough leads to get rid of the extensions. They did not heat fast enough. The 22060 only has 15" leads which don't come close to being long enough with long tubes.

 

[briangsxr1000]

Holley Dominator. Problem solved.

When you said new O2 sensor with longer wires do you mean extension harness? If so that could be an issue.
Otherwise I’d assume BJ has had some suggestions.
Good luck.
-J

Oddly enough the only sensors that heat properly are the OEM ones with the extensions. When I installed sensors with longer leads-Bosch or NTK neither heat properly and only pull arond 1 amp for a few seconds and drop down to 200mA. The oem sensors start around 1.5 amps and pull 600mA consistently which gets them hot within the 60 second closed loop delay.
Nothing makes sense on this car I swear... lol

 

[biminiLX]

I had brand new NTK 22106 which gave me long enough leads to get rid of the extensions. They did not heat fast enough. The 22060 only has 15" leads which don't come close to being long enough with long tubes.

Good to know. Have you unclipped the harness over the trans to have extra length?
Can you run the stock sensors tgat worked correctly?
-J

 

[briangsxr1000]

Good to know. Have you unclipped the harness over the trans to have extra length?
Can you run the stock sensors tgat worked correctly?
-J

Sure I can run them with the extenders but the goal was to get fresh sensors in and not run any sort or aftermarket extenders in between.
The goal was to eliminate potential issues and I created them by replacing sensors.

 

[biminiLX]

I understand. But the old OEM with extensions currently work? If so run those and send the non functioning NTKs back?
Did you understand what I meant about the wiring harness?
If the harness mod works then I’d try the NTK 22060 that BJ recommended.
End of day if the OEM works with the extensions then it works.
-J

 

[Vinnie_B]

Pull your harness off and send out to have it customized to extend the front 02 sensors plugs at the header.Use factory O2 sensors W/No extensions and your good to go....easy!

 

[briangsxr1000]

I understand. But the old OEM with extensions currently work? If so run those and send the non functioning NTKs back?
Did you understand what I meant about the wiring harness?
If the harness mod works then I’d try the NTK 22060 that BJ recommended.
End of day if the OEM works with the extensions then it works.
-J

I have a set of the sensors BJ recommended and another in the 30" length that fit correctly without removing the sensor connectors from the clips in the harness. All of these NTK sensors measure 6.5 ohms +\- .5 ohm and for whatever reason my car doesn't like that. They will heat but not quickly enough. My oem sensors measure 3 ohms and they heat properly.
For whatever reason the car doesn't provide enough current to heat the higher ohm heaters.

 

[briangsxr1000]

Pull your harness off and send out to have it customized to extend the front 02 sensors plugs at the header.Use factory O2 sensors W/No extensions and your good to go....easy!



View attachment 1804539

I appreciate the advice but the extensions aren't the issue. If my oem sensors ever crap out I don't have a suitable option that works in this car. Newer sensors have a higher resistance and they don't heat fast enough for whatever reason.
If anything I would extend the wiring myself with the harness in the car when I do a clutch someday. That's easy work with the trans out.

 

[biminiLX]

Try OEM Motorcraft replacement to test?
Hope it works out man. I’d trust BJs advice he knows these cars well.
-J

 

[briangsxr1000]

Try OEM Motorcraft replacement to test?
Hope it works out man. I’d trust BJs advice he knows these cars well.
-J

The new oem replacements are made by bosch. Trying to locate some old stock of the NTK to keep around.
I'll just use what works for now.