what if I have pipes and want to add a K&N replacement filter? would I need a re-map?

sorry to thread-jack. i didn't want to start a new thread.

 

If those people pulled there plugs they would find they are running lean.

 

Thanks guys. I think I will just wait until I get the pipes and fuel mgmt system and do it all at once.

 

 

why not wait and do it all at once.

 

Now that's the smartest way to go.

And you SHOULD do the fuel management with the intake. Yes it not an absolute necessity, but as lean as they have these 07 and up engines running. Putting a Big Sucker, Heavy Breather, or even a K&N WILL make it run even leaner, and hotter.

Pipes alone don't have much of an overall effect on the Air Fuel ratio because with the stock intake it just can't flow any more air than it already is. But adding any kind of intake upgrade will let the engine get more air in and lean out an AF ratio that's already too lean for most people.

The stock ECM only has a limited adjustment range and its all based on how much air it THINKS is getting into the engine. Remember its not like the OBDII system in your car that uses a MASS sensor to actually measure the incoming air volume and adjusts the fuel and timing inputs accordingly.

The Delphi system used in our bikes is of the older MAP based system all cars were legally forced to abandon in 1995. So it only measures the manifold air pressure and temperature, not the actual volume. So it can only guess at how much air is getting in and just uses the O2 sensors to see if its close to the AF ratio the engineers told it is right.

Narrow band O2 sensors are more like go/no go gauges than actual measuring tools so the ECM doesn't get anything like a real AF ratio measurement from them. Its just tells the ECM its within its design range. If it is within specs, fine, if not, its not going to try to fix the problem, its going to scream for help by lighting up the CHECK ENGINE light.

So with that bit of explanation behind us adding a larger freer flowing intake can actually make things worse in two ways. The first is that a better intake will show a lower air pressure to the MAP sensor so it Will reduce the amount of fuel it puts in instead of increasing it. While at the same time the intake is letting more air get into the engine. So you loose two ways.

If anyone really is running a better than stock intake without any modifications to the stock ECM's MAP's. IMHO they're just asking for trouble, the big expensive kind. Cause there is no way in hell the MOCO is going to fix a cooked engine under the warranty.

 

well i have an opinion too
you need fuel management even if you dont change breather or exhaust because epa screwed it up for air cooled engine

 

As you can see by the replies, everybody's got an opinion.

The '07 & up ECMs feature Adaptive Learning. They can adjust.... up to a point. Prevailing wisdom seems to feel the ECM will adjust to most slipons allowing OEM A/F ratios throughout the power band. It's also widely perceived that increased airflow with a breather it will also adjust sufficiently since although you are opening up the intake you're not achieving optimum flow because you don't have the advantage of also opening up the exhaust.

IMO, enhaust OR breather only and you'll have no problem. Do both and you have to do something with fuel. That can entail a tuning system or something as simple as having a dealer use the Tools menu on the Digital Technician II to reset your Adaptive Fuel value. A simple 10 minute procedure that will maintain the OEM A/F ratios without aggravating leanness.

I gleaned this info from a tech that used to develop the Stage calibration matrixes at the Development Center. They come up with all kinds of crazy configurations for their own bikes that H-D can't release to customers.

TL