O2 sensor crosstalk?
Crosstalk is caused by reversion. It has everything to do with the exhaust system itself, more specifically the O2 sensor location. With the newer style factory head pipe/collector there will always be some reversion in the collector area, however there will be considerably more reversion in this area when the catalyst is removed as this area is completely opened up, unfortunately this specific region of turbulence is where the 2010-2012 O2 sensors are mounted and the sensors can easily pick up residuals from the other cylinder. This is also the specific reason why they located the O2 sensors upstream in pre-2010 models. The specific amount of sensor crosstalk and if it will affect the tune and more importantly running quality really depends on the specific mods, the mufflers, and also heavily on how much overlap the cams have. Likely the biggest consideration to how the end results are affected depends on how accurate the calibration is in the first place, if the O2 integrator does not need to lean on the sensors to try to correct the fuel delivery there will not be too much of a problem, however it can go the other way at times as well especially if the cams have any amount of overlap. The other consideration is if you are using the factory O2 sensors to maintain the tune in closed loop or if you are using them to actually develop the tune with a new combination which if there is crosstalk can cause you to chase your tail at times. Hope this info helps
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Jamie Long / Fuel Moto USA
The USA's Leader V-Twin EFI & Performance www.fuelmotousa.com
Contact 920-423-3309
Email jamie@fuelmotousa.com
Jamie Long / Fuel Moto USA
The USA's Leader V-Twin EFI & Performance www.fuelmotousa.com
Contact 920-423-3309
Email jamie@fuelmotousa.com
Actually this is a great example, reversion can reach nearly all the way up an exhaust pipe with some combination so imagine what can happen when they are only a few inches up the collector.
Tourer
Joined: Dec 2006
Posts: 492
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From: Castle Rock, CO
I can chase perfection, but is it worth it - will I feel it?
5th Gear
Joined: Jan 2011
Posts: 9
Likes: 0
From: Massachusetts
This is a good thread! First off I want to say that I am NOT challenging anyones facts. I am just posting the results of my experience.
The bike is a 2010 FLHX. I added an A/C and Rinehart 4" slip-on to the stock head pipe and using TTS did a few VTune runs. Other than the heat produced by the Cat the bike ran really well. The only complaint I had was an occasional pop when shifting from 1st to 2nd. Closing the throttle coming down a hill would NOT cause popping. I checked the entire exhaust system for leaks and found none. As it would happen only occasionally I just lived with it. This past Winter I decatted the head pipe. When spring came I did some VTuning and most of my VEs stayed within 2%. The biggest change was 3.5% and this only a few VEs.
The results:
I do not notice any difference in the way the bike runs except it is cooler. MPG has not changed. The occasional pop when shifting was still there. Although, I have recently added some additional fuel in the decel range and it is now almost nonexistent. I have put the bike away for the winter as we already have snow on the ground (NH) but next Spring I am going to experiment with the Closed Spark Timing Table to see if I can totally eliminate the pop.
The bike is a 2010 FLHX. I added an A/C and Rinehart 4" slip-on to the stock head pipe and using TTS did a few VTune runs. Other than the heat produced by the Cat the bike ran really well. The only complaint I had was an occasional pop when shifting from 1st to 2nd. Closing the throttle coming down a hill would NOT cause popping. I checked the entire exhaust system for leaks and found none. As it would happen only occasionally I just lived with it. This past Winter I decatted the head pipe. When spring came I did some VTuning and most of my VEs stayed within 2%. The biggest change was 3.5% and this only a few VEs.
The results:
I do not notice any difference in the way the bike runs except it is cooler. MPG has not changed. The occasional pop when shifting was still there. Although, I have recently added some additional fuel in the decel range and it is now almost nonexistent. I have put the bike away for the winter as we already have snow on the ground (NH) but next Spring I am going to experiment with the Closed Spark Timing Table to see if I can totally eliminate the pop.
Stellar HDF Member
Joined: Sep 2007
Posts: 2,459
Likes: 674
From: Vancouver Island B.C.
Lower the corresponding cells on the DE table first.
Cruiser
Joined: Sep 2011
Posts: 124
Likes: 0
From: VA
So recently I have been told (during my search for a new limited) that if I put on new pipes, Jackpot, fullsack, or 2009 stock pipes (catless) along with a/c (maybe cam too) and put on a Power Commander V that I don't need to worry the 02 sensors or the location as the dealer will just plug them up anyway..I may sound naive, well I am a bit when it come to the newer fuel systems and their workings, I'm reading all I can, but I'm not yet up to speed here yet. So the question is. Is this correct info? Should I be planning on a setup that won't use the 02 sensors? Can this be done? What are the pros and cons? Or should I run as fast as I can from the dealer?
Ultimate HDF Member
Joined: May 2008
Posts: 7,439
Likes: 884
From: 'Noke, VA
The Delphi ECM is a pretty amazing computer. Why would you want to hamstring it by unplugging two of the sensors?
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5th Gear
Joined: Jan 2011
Posts: 9
Likes: 0
From: Massachusetts
Grappa,
When you take the O2 sensors out of the equation (yes you can do this) you are running the ECM in open loop. In other words the ECM cannot monitor the amount of Oxygen in the exhaust and make corrections for poor fuel, altitude, temperature, etc. This kind of defeats the intended purpose of the ECM. A stock bike (no modifications) will run the idle and midrange in closed loop and WOT will run in open loop.
When you take the O2 sensors out of the equation (yes you can do this) you are running the ECM in open loop. In other words the ECM cannot monitor the amount of Oxygen in the exhaust and make corrections for poor fuel, altitude, temperature, etc. This kind of defeats the intended purpose of the ECM. A stock bike (no modifications) will run the idle and midrange in closed loop and WOT will run in open loop.
Extreme HDF Member
Joined: Dec 2007
Posts: 13,402
Likes: 941
From: Illinois
It is pure BS. The sensors are about 4 inches up the head pipe. The head pipes then terminate into a collector. The cat starts about another 4 inches into the collector. The cat is so free flowing that there is no noticeable change in back pressure. The chance of exhaust gasses going back into the head pipe is almost impossible.