Can I force the PCM to recalibrate more quickly after an O2 sensor installation? - JeepForum.com
 
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post #1 of 9 Old 01-17-2012, 03:02 PM Thread Starter
josephmartins
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Can I force the PCM to recalibrate more quickly after an O2 sensor installation?

Shortly after a CEL for one of my upstream O2 sensors I experienced a huge drop in fuel efficiency--about 50%. I am going to change the sensors tomorrow. Is there a way to speed up the time it seems to take the PCM to adapt to the new sensors? Or is driving and time the only solution?


Kind regards,

Joe Martins
Milford, NH

12 Wrangler Sahara JK8, 01 WJ Limited, 96 XJ Classic, 00 XJ Sport, 90 XJ Wagoneer, 97 ZJ Limited, 5.2, 98 ZJ Limited, 5.2
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post #2 of 9 Old 01-17-2012, 03:10 PM
Double E
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Disconnect battery, then touch disconnected battery cables together or depress the brake pedal several times while disconnected.

Clean battery contacts while your in there. Clean out your throttle body & IAC valve too for good measure.
Change fuel filter if you want to really stack the maintenance/mileage deck in your favor.

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post #3 of 9 Old 01-17-2012, 08:27 PM
specia1k
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Why would you touch the battery cables? I agree with disconnecting the battery, the reason being that you don;t want any electrical shorts, etc. to take place when replacing engine components (i.e. O2 Sensors, other sensors, spark plugs, etc.). I'd be interested to hear the logic behind touching the pos & neg terminals together. Would be weary of following that suggestion without details to support the comment.

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post #4 of 9 Old 01-17-2012, 08:39 PM
MeanGreenZJ
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Doing that is not a good idea on VIN coded PCM's. You can end up with a corrupted VIN in the PCM with a start stall issue. It's rare but it does happen even from something as simple as the battery going dead.





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Originally Posted by specia1k View Post
Why would you touch the battery cables? I agree with disconnecting the battery, the reason being that you don;t want any electrical shorts, etc. to take place when replacing engine components (i.e. O2 Sensors, other sensors, spark plugs, etc.). I'd be interested to hear the logic behind touching the pos & neg terminals together. Would be weary of following that suggestion without details to support the comment.
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post #5 of 9 Old 01-18-2012, 01:37 AM
ratmonkey
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Look up the driving cycle to quickly set the monitor cycles. It's actually almost impossible to follow without a closed course to drive.

'97 zj 5.2, some stuff, some other suff, and some things that even work sometimes.

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post #6 of 9 Old 01-18-2012, 07:40 AM
Terminator2
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Quote:
Originally Posted by MeanGreenZJ View Post
Doing that is not a good idea on VIN coded PCM's. You can end up with a corrupted VIN in the PCM with a start stall issue. It's rare but it does happen even from something as simple as the battery going dead.

http://www.youtube.com/watch?v=h87IC...2mDEAXdoIjPnhc
That is so rare it is not even funny. It is about as likely as you being struck by lightning. How many hundreds of millions of cars have dead battery issues worldwide each year? How many of those result in corrupted ECMs? Probably less than 1 out of every million.
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post #7 of 9 Old 01-18-2012, 12:10 PM
BandGauto
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You can disconnect the positive cable from the battery (leave the negative hooked up) and touch the positive cable to any good ground for 30 seconds or just hook up an OBDII scan tool after you replace the 02 sensor and erase the code. It will then take a few driving cycles for all the monitors to reset. If you have a decent scan tool it will tell you which monitors are reset and which are not. If you dont have a scan tool most auto parts stores like autozone will do it for you. Also after changing the 02 sensor make sure the 02 fuse in the distribution box (under the hood) didnt pop and replace it if it did.
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post #8 of 9 Old 01-18-2012, 02:24 PM
MeanGreenZJ
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I'm not sure what the ratio of this issue is worldwide. But people still do play the lottery.




Quote:
Originally Posted by Terminator2 View Post
That is so rare it is not even funny. It is about as likely as you being struck by lightning. How many hundreds of millions of cars have dead battery issues worldwide each year? How many of those result in corrupted ECMs? Probably less than 1 out of every million.
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post #9 of 9 Old 01-18-2012, 02:27 PM
MeanGreenZJ
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If you have a decent scan tool it will allow you to reset the PCM without disconnecting the positive cable from the battery.


Quote:
Originally Posted by BandGauto View Post
You can disconnect the positive cable from the battery (leave the negative hooked up) and touch the positive cable to any good ground for 30 seconds or just hook up an OBDII scan tool after you replace the 02 sensor and erase the code. It will then take a few driving cycles for all the monitors to reset. If you have a decent scan tool it will tell you which monitors are reset and which are not. If you dont have a scan tool most auto parts stores like autozone will do it for you. Also after changing the 02 sensor make sure the 02 fuse in the distribution box (under the hood) didnt pop and replace it if it did.
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