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Discussion Starter #1
97 Cougar 4.6: I have 3 of the four O2 sensors out, the pre-cat on the passenger side is horrible to reach. I can get a wrench on it, but between the tans lines and the starter I can't move the wrench enough. Any insight would be greatly appreciated. I plan on picking up a ratcheting wrench tomorrow. Any other ideas?
Thanks
 

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I used two different wrenches. As it turned out, the two different brands of wrench had a slightly different angle on the head which allowed me enough room to get a bite on the sensor as I loosened it.

That's what I did, but the general consensus is to use a crow's foot.
 

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I'm with Brandon on that too.... I had to try a few different 7/8 wrenches before I got one with the right angle. Plus being a contorsionist could help. :rolleyes:
 

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Discussion Starter #4
Thanks for the info, I'll see what I can figure out. Hopefuly a racheting wrench will give me some benegif or maybe a stubby. What is a crow's foot?
 

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I picked up a set of crow's feet today, between that and a standard wrench I got it off and the new on in. I had to bounce between the open end and box end of the wrench to snug the sensor up. I still thing it might be a little easier with a ratcheting wrench, but the hardware store didn't have a 7/8 ratcheting. Thanks for all the help.
 

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Discussion Starter #7
Ok, got all four replaced, the battery was disconnected for a few days because of the starter wire. The ecu should have reset. I drove it to work and on the way home check engine is on again. Autozone pulled the codes and all 4 o2 sensors. I had checked NAPA's website on the past numbers for front and rear sensors and installed them that way. so, options are: napa is wrong, bad sensors, corroded connections, ecu still needs reset. Any ideas on how to test and prove?
 

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97 T Bird with 111000 miles - Codes PO135 PO141 PO155 PO161 - Have checked wiring harness and it shows to be good. If I clear codes with motor not running the codes pop up as soon as I start driving, but if I clear codes with motor running, the codes don't reappear until I cut motor off and restart. Help!
 

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What did you do to prove out the harness? Do you have 12V on circuit 361? Have you backprobed the pins at the EEC to check for voltage and continuity on the heater circuits?
 

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check mass air flow sensor and when you disconnect the battery disconnect both cables and touch them together might have to run a jumper wire to both of them and if you want to be anal like I am turn the headlights on while you do this leave it like that for at least 5 minutes it is called cleansing the ecm....did that many times and it does help clear all the codes even though it sounds stupid
 

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From prior reading, when all four heater circuits fail at the same time it tends to be the PCM drivers.

The front O2 heater circuits go through the engine harness, the rears go through the transmission harness. Unless both harnesses failed in the same way at exactly at the same time, it's likely the PCM is the problem.
 

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Discussion Starter #16
Brandon, can you explain the pcm drivers? I'm not familiar, what are they, how to test, how to fix? Thanks a lot.
 

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Have a look at this thread: http://forums.tccoa.com/showthread.php?t=124881

I am guilty of having partially hijacked the thread... :facepalm: but my problem turned out to be a major short at the back of the engine harness. But - I had a failure only on the front O2 heater circuits, not all four. Every time I've seen reference to a failure on all four at one - and seen the resolution posted - it has been the PCM.
 

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check mass air flow sensor and when you disconnect the battery disconnect both cables and touch them together might have to run a jumper wire to both of them and if you want to be anal like I am turn the headlights on while you do this leave it like that for at least 5 minutes it is called cleansing the ecm....did that many times and it does help clear all the codes even though it sounds stupid
Doesn't sound stupid, anal maybe.... :) I read this earlier and have been thinking about it, given my electronics background I wanted to elaborate.
The codes are stored in volatile memory, like RAM in a PC, meaning remove power the memory is gone. It tends to stay after power removal for some time b/c of caps in the ECU, I've been told about 45 min. I would agree turning on the lights in order to accelerate this process, but have some issue with shorting the pos & neg cables together. Here's why:
Caps charge and discharge very fast; upon removal of power , the battery, the caps will be full charged. Then touching the pos to neg will cause and immediate discharge, potentially very high current, granted for a very short time. This high current can stress or damage other components in the system, ECU, etc. Probably won't instantly fail, but could be stressed enough to cause failure over time. By turning on the lights after the battery is disconnected you in essence short the pos to neg, but with some resistance in between. This provides a much slower discharge and less current, thus less likely to cause damage. I say turn on the lights after you disconnect b/c the light draw a significant amount of current off the battery (that's why your battery doesn't last long with lights on and engine not running). When you go to lift the neg cable and the lights are on there will be a arch at the neg terminal, which will begin to degrade the battery post and the neg clamp. All of this may prove to be insignificant in the long run, depending on how sensitive the electronics are in the ECU and the rest of the circuitry.
 

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There's also the "What's wrong with the underhood light and leave the door open to use the courtesy lights?" drain.

But you may need to do the cable bump after several minutes anyway ... what with the changeover to LEDs for interior/under hood lighting and HIDs for head lights with people.

They way Ford RECOMMENDS is to pull the ECC fuse, and crank the car for at least 15 seconds. Doesn't help if you're on the SC which doesn't use the ECC fuse ...

RwP
 
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