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I checked the resistance. 3.6Ohm on each. Will the .3Ohm make a difference? I got the recommended pack from you Cliff, and they said they were 3.3Ohm.
My car still throwing P0141 and P0161. (12V in, Heat sensor wire out)
Any ideas?
This statement "(12V in, Heat sensor wire out)" confuses me--the resistor pack should just be connected across the heater wires, as as substitution for the O2 sensor heaters.
They are red/yellow and white/black on the passenger side, and red/yellow and tan/yellow on the driver's side. The red/yellow wire if +12V, the others go back to the PCM which controls the ground connection of the heater, and monitors the current being drawn.
The shop manual does not say much about the details of the heater monitoring process--I did find this:
Quote:
Embedded with the sensing element is the HO2S heater. The heating element heats the sensor to temperatures of 800°C (1400°F). At approximately 300°C (600 °F) the engine can enter closed loop operation. The VPWR circuit supplies voltage to the heater and the PCM will turn on the heater by providing the ground when the proper conditions occur.
Since model year 1998 a high power HO2S heater and heater control system have been installed on the Stream 1 HO2S sensors of most vehicles. The high power heater reaches closed loop fuel control temperatures faster, which allows closed lop engine operation sooner. The use of this heater requires that the HO2S heater control be duty cycled, to prevent damage to the heater.
The 6 ohm design is not interchangeable with new style 3.3 ohm heater. Use the appropriate service part number.
HO2S Heaters, front and rear
The HO2S heaters are monitored for proper voltage and current. A HO2S heater voltage fault is determined by turning the heater on and off and looking for Corresponding voltage change in the heater output driver circuit in the PCM.
A separate current-monitoring circuit monitors heater current once per driving cycle. The heater current is actually sampled three times. If the current value for two of the three samples falls below a calibratable threshold, the heater is assumed to be degraded or malfunctioning. (Multiple samples are taken for protection against noise on the heater current circuit.)
I also found a reference to an "inferred HO2S temperature" which appears to be calculated from monitoring the voltage and current draw of each heater--and this may be our plan's downfall.
As heating elements get hotter their resistance rises and the current drawn drops. It may be that the PCM is programmed to expect the typical curve that an O2 sensor heater (maybe even an O2 sensor heater immersed in a hot gas) generates, and the resistor pack has a different curve?
I assume that you had reset the codes using a scan tool, and did not just expect them to go away...
__________________
-cliff knight- My Mustang
2003 GT, UPR X, Magnaflow, 180° stat,
PP 70mm TB & plenum, Sniper tuned
3.73s, 262 rwHP/305 ft.lb.
Multi-fuel: burns gas and rubber...
12V in meaning... The plug on the board had an in and out. I know that it can go either way. Was just to clarify/repeat that I was using 12V on the opposite end of the pack than the sensor wire.
I used a different 12V source than the red/yellow (I used the fuse panel, as this is all in my cabin, and it seems the red/yellow is common power to all sensors). But I would assume that is the same, seeing as how the ecu monitors the ground (sensor wire). I would assume it is using the sensor wire (ground) to open/close the circuit. Correct?
Yes I cleared the codes. A few attempts.
I guess I could check my front O2sensor elements at a few different points and maybe use relays/timers to simulate the resistance...
You were correct in saying this would be a pain in the ass.
Last edited by MikeInCape; 04-30-2009 at 06:21 PM.
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(12V in, Heat sensor wire out)
