EFI question
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Extreme HDF Member
Joined: Aug 2007
Posts: 17,625
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From: Blairsville GA
EFI question
I bought an '08 crossbones with Rush slip-ons, SE aircleaner and the dealer download. Bike runs fine, with a slightly elevated idle.
In order to fit the bags I want to use, I need to use a different exhaust. I have the pipes I want to use, and they are without holes for O2 sensors.
My assumption is that I should get a Power Commander and eliminate the sensors, as this is a cheaper (by $400) option to getting a new set of pipes with the holes for the sensors.
Is there a flaw in my thinking? Do the O2 sensors make a diff in how the bike runs, or is it just EPA? Will the PC work on top of the dealer download? I'm new to EFI. Thanks!
In order to fit the bags I want to use, I need to use a different exhaust. I have the pipes I want to use, and they are without holes for O2 sensors.
My assumption is that I should get a Power Commander and eliminate the sensors, as this is a cheaper (by $400) option to getting a new set of pipes with the holes for the sensors.
Is there a flaw in my thinking? Do the O2 sensors make a diff in how the bike runs, or is it just EPA? Will the PC work on top of the dealer download? I'm new to EFI. Thanks!
Road Master
Joined: Oct 2006
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Road Master
Joined: Oct 2006
Posts: 810
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Elite HDF Member
Joined: Sep 2006
Posts: 3,592
Likes: 6
From: Florida
JMO----the O2 sensors are the only device on the bike that actually tells the computer what is happening in the combustion chamber. By eliminating the O2's you are eliminating that source of input for tunability on the fly.
You can add bungs to your pipes very inexpensively. Here is one option:
http://cgi.ebay.com/ebaymotors/Angle...Q5fAccessories
I reccomend you take a look at factory pipes (or aftermarket) and look at the location of the bungs. They are generally located within 6 or 8 inches of the exhaust port. The angled bung should be located so the sensor is sticking into the pipe with the exhaust flow and not against it. Both straight and angled bungs have been used, I just prefer the angles because it makes good engineering sense and that is the way most are installed.
To install the angled bungs, you should mark with a Sharpie where you want them. Take the pipes off the bike and drill a small pilot hole to start...like a #30 (.1285"). Step it up from there to the size of the threads on the O2 sensor. As you step up the holes you should angle the hole to match your bung. Have a wood dowel handy that fits through the bung fairly snug. When you can put the bung in place with the dowel through both the bung and the exhaust pipe, you are ready to weld. Remember to drill slow (500 rpm max) when drilling steel so the bit doesn't just burn up and stop cutting.
You can add bungs to your pipes very inexpensively. Here is one option:
http://cgi.ebay.com/ebaymotors/Angle...Q5fAccessories
I reccomend you take a look at factory pipes (or aftermarket) and look at the location of the bungs. They are generally located within 6 or 8 inches of the exhaust port. The angled bung should be located so the sensor is sticking into the pipe with the exhaust flow and not against it. Both straight and angled bungs have been used, I just prefer the angles because it makes good engineering sense and that is the way most are installed.
To install the angled bungs, you should mark with a Sharpie where you want them. Take the pipes off the bike and drill a small pilot hole to start...like a #30 (.1285"). Step it up from there to the size of the threads on the O2 sensor. As you step up the holes you should angle the hole to match your bung. Have a wood dowel handy that fits through the bung fairly snug. When you can put the bung in place with the dowel through both the bung and the exhaust pipe, you are ready to weld. Remember to drill slow (500 rpm max) when drilling steel so the bit doesn't just burn up and stop cutting.
HD's EFI system is a Narrow band closed loop system. Realistically the O2 sensors only work for a very small portion of time and a very small range of A/F ratios. Using a PCIII to elminate them is not that big of a deal as all 2006 and older bikes are all open loop EFI systems that have no O2 sensors at all. As far as I know, I have never really heard of any problems with the EFI system that had to do with lack of O2 sensors. With that being said, it is better to keep the O2 sensors, better yet would be a wide band closed loop system like the thunder Max system. If you do the PCIII you will be fine, just fork out the few extra bucks for a dyno tune and you will be more than happy.
Elite HDF Member
Joined: Sep 2006
Posts: 3,592
Likes: 6
From: Florida
Sonar Chris...."more than happy"? George Carlin called that a "psychiatric diagnosis"~~~as in, "He was just a little bit...more than happy." LOL
Daddy Knuck, it really depends on what's right for you. Are you going to make any other performance related changes in the future? If you are, those dyno runs add up quick. You live where you can ride through a big variance of elevation and temp. That alone may be enough reason to keep the O2 sensors. The narrow band sensors are more of a lean/good/rich switch where the wide band sensors tell the computer what exactly is going on.
And yes, the PC will work on top of the dealer download.
P.S. Boosteddelslow....it is just a step backwards in tech. You would not buy a new Vette and buy a component that eliminates the o2's, so I can't see doing it on a Harley either.
Daddy Knuck, it really depends on what's right for you. Are you going to make any other performance related changes in the future? If you are, those dyno runs add up quick. You live where you can ride through a big variance of elevation and temp. That alone may be enough reason to keep the O2 sensors. The narrow band sensors are more of a lean/good/rich switch where the wide band sensors tell the computer what exactly is going on.
And yes, the PC will work on top of the dealer download.
P.S. Boosteddelslow....it is just a step backwards in tech. You would not buy a new Vette and buy a component that eliminates the o2's, so I can't see doing it on a Harley either.
Last edited by mopardave; Dec 20, 2008 at 04:36 PM. Reason: P.S.
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Road Master
Joined: Oct 2007
Posts: 1,028
Likes: 1
for just a/c and slipons. what makes the pc better than the down load??
with the down load you keep your warranty.
with the pc. warranty???
with the down load you keep your warranty.
with the pc. warranty???
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Elite HDF Member
Joined: Sep 2006
Posts: 3,592
Likes: 6
From: Florida
The HD download's are (or were?) only for HD and HD/SE parts and only SE parts that they approve.
The dealers generally don't want to warranty anything that has been modified, regardless of the warranty laws.
The dealers generally don't want to warranty anything that has been modified, regardless of the warranty laws.