Researching HPTuners, mileage and other newb ?s
07-13-2006, 01:35 PM
#11
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You have it right for the most part.
There are four 02 sensors. although the rear o2 sensors (after cats) do not have anything to do with the tunning aspect, there only job is to make sure the cats are working properly.
So what most people do is remove one of the rear o2 sensors and install the wide band. This will set a SES but HPTuners can fix that.
The other way is to replace one of the front o2 sensors with a wide band that will simulate the nerrow band for the PCM and also work as a wide band. Not all wide bands can do this. but It can be done. I'd just replace one of the Cat monitoring rears with the wide band and tune away.
Yes you do need the PRO version to log the wideband along with all the other PIDs with the scan progam of HP tuners.
If you do go for the rear o2 sensor replacement I'd do the left side. It is the leaner of the two.
There are four 02 sensors. although the rear o2 sensors (after cats) do not have anything to do with the tunning aspect, there only job is to make sure the cats are working properly.
So what most people do is remove one of the rear o2 sensors and install the wide band. This will set a SES but HPTuners can fix that.
The other way is to replace one of the front o2 sensors with a wide band that will simulate the nerrow band for the PCM and also work as a wide band. Not all wide bands can do this. but It can be done. I'd just replace one of the Cat monitoring rears with the wide band and tune away.
Yes you do need the PRO version to log the wideband along with all the other PIDs with the scan progam of HP tuners.
If you do go for the rear o2 sensor replacement I'd do the left side. It is the leaner of the two.
07-13-2006, 02:32 PM
#12
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Originally Posted by Wilde Racing
You have it right for the most part.
There are four 02 sensors. although the rear o2 sensors (after cats) do not have anything to do with the tunning aspect, there only job is to make sure the cats are working properly.
So what most people do is remove one of the rear o2 sensors and install the wide band. This will set a SES but HPTuners can fix that.
The other way is to replace one of the front o2 sensors with a wide band that will simulate the nerrow band for the PCM and also work as a wide band. Not all wide bands can do this. but It can be done. I'd just replace one of the Cat monitoring rears with the wide band and tune away.
Yes you do need the PRO version to log the wideband along with all the other PIDs with the scan progam of HP tuners.
If you do go for the rear o2 sensor replacement I'd do the left side. It is the leaner of the two.
There are four 02 sensors. although the rear o2 sensors (after cats) do not have anything to do with the tunning aspect, there only job is to make sure the cats are working properly.
So what most people do is remove one of the rear o2 sensors and install the wide band. This will set a SES but HPTuners can fix that.
The other way is to replace one of the front o2 sensors with a wide band that will simulate the nerrow band for the PCM and also work as a wide band. Not all wide bands can do this. but It can be done. I'd just replace one of the Cat monitoring rears with the wide band and tune away.
Yes you do need the PRO version to log the wideband along with all the other PIDs with the scan progam of HP tuners.
If you do go for the rear o2 sensor replacement I'd do the left side. It is the leaner of the two.
07-14-2006, 09:06 AM
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Originally Posted by Wilde Racing
...
So what most people do is remove one of the rear o2 sensors and install the wide band.
....
So what most people do is remove one of the rear o2 sensors and install the wide band.
....
Edit: Thought of this just after posting. Of course there is a difference. That is why there are O2 sensors before and after the cats.
By measuring the change in free O2 content, the PCM knows whether or not the cats are working. Since the PCM uses the pre-cat sensors to do its "tuning" in closed loop mode, I would suspect that this location gives the correct AFR. The question now is, assuming the cats are working properly, what is the offset to apply to a post-cat measurement so that the tune will be correct? Or is this even possible?
Last edited by GMC_DUDE; 07-14-2006 at 09:18 AM.
07-17-2006, 07:35 AM
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Originally Posted by GMC_DUDE
I've always wondered about this. Since the wideband only measures free O2, wouldn't the redox reactions taking place inside the cat cause an abnormally rich reading, since the free O2 has just been used up to turn the evil HC's and carbon monoxide into "harmless" CO2 and H2O? True, some of the oxygen for the reactions is supplied by the NOx (2NOx --> N2 + xO2 hard to write chemistry equations here), but I think a lot of the free O2 would be used up as well. Has anyone done a "before cat / after cat" comparison to note any difference? I would be very interested.
Edit: Thought of this just after posting. Of course there is a difference. That is why there are O2 sensors before and after the cats. By measuring the change in free O2 content, the PCM knows whether or not the cats are working. Since the PCM uses the pre-cat sensors to do its "tuning" in closed loop mode, I would suspect that this location gives the correct AFR. The question now is, assuming the cats are working properly, what is the offset to apply to a post-cat measurement so that the tune will be correct? Or is this even possible?
Edit: Thought of this just after posting. Of course there is a difference. That is why there are O2 sensors before and after the cats.
By measuring the change in free O2 content, the PCM knows whether or not the cats are working. Since the PCM uses the pre-cat sensors to do its "tuning" in closed loop mode, I would suspect that this location gives the correct AFR. The question now is, assuming the cats are working properly, what is the offset to apply to a post-cat measurement so that the tune will be correct? Or is this even possible?So just forget about the crappy info I posted two posted up.
Unless some-one can figure out the error before and after the cat as GMC DUDE posted.
07-17-2006, 08:45 AM
#15
Originally Posted by Wilde Racing
So just forget about the crappy info I posted two posted up. Unless some-one can figure out the error before and after the cat as GMC DUDE posted.
Unless some-one can figure out the error before and after the cat as GMC DUDE posted.
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