After putting it on I haven't noticed much difference, maybe a-little stronger but it's too hard to tell just by feel. Fuel milage seems to be the same but I havent measured it properly. I definately have not noticed any degradation in performance. I was more concerned with long term effects on the EFI system due to poor filtration. I am using the stock pre-filter in conjunction with the K&N so hopefully that helps.

 

You say that the the EFI system is incapable of adjusting the fuel flow for additional air through a low restriction filter. It would have to be capable of adjusting the fuel flow, that's how it compensates for altititude by varying the length of time that the injector is on. The range is from 1.5 - 8.0 milliseconds depending on fuel requirements. The manifold absolute pressure is also monitored which is what changes with altitude. Seems to me that the pressure differential across an air filter would also affect the manifold pressure and compensate for it. I've used K&N air filters on my last 3 ATV's and had no problems. I have always checked the intake manifolds during inspections and found no traces of dust in them. I do service the air filters quite often though.

 

You can bolt on ex., cams, port the head, change filter, adn even run with the air box off and the polaris efi quads are fine. I'm not saying the adj. or don't adj. Polaris can even answer that one for us. I do know that they are pig rich from the factory and we havn't had any problems doing all sorts of mods to them.

Bryce, what is this megaaquirt you talk about? Do you make it do you work fo rthem do you have one? I'd like to get my hands on one if it does what you say properly.

 

I've been running a K&N on my 700 since day one. I now have almost 900 miles on mine and haven't had one problem from it. I run the pre-filter on it also. I've never seen any dust on the inside of the filter tubes. I've also added the 800 intake tube on mine. The EFI will adjust for air flow and so on. It's just like your truck or car. It has to be able to up to a certain point just because the the Altitude and little mods. There would be no purpose of EFI if it didn't adjust.

 

You might make changes to a Polaris EFI quad without hurting it. However, if you are looking to increase the performance when you make the change, you need to change the fuel mapping. Even the Commander has a different fuel map for different filters. The only true way to perfectly control the fuel mapping is by monitoring an O2 sensor. Either closed loop or by setting up the fuel map using a wide band O2 sensor. Just because the EFI changes the fuel mapping due to altitude does not mean it will properly adjust for an intake or exhaust change. And I would not make a cam change without changing the fuel map and spark timing. Seems to me that most people know enough to change the carb jets when you modify a carbed engine. I am suprised anyone would argue that you must make fuel map adjustments when you modify an EFI quad. It may be that EFIs typically run rich. However, each individual engine is different because of variations in the sensors and injectors. So we can't make a blanket statement about all EFIs that you can change the intake and exhaust without harming the engine.
JMO
Bryce

 

The EFI on the Polaris is nothing like a car or truck. Cars and trucks have O2 sensors that allow the ECM to close the loop on the engine fuel. The Polaris does not. It runs open loop. Cars and trucks also have additional sensors that the Polaris EFI does not. The Polaris EFI and the other quad EFI systems are fairly simple. Heck even auto tuners know that if they want maximum performance or change the engine, they modify the fuel maps.
Bryce

 

Trust me you cna itall all of the parts I listed above and still not need to adjust the fuel mapping. We have tried with powercommanders adn tfi controllers. Plus after installing all of our mods the quad still runs rich, we check plugs, and hooked up a new air fuel meter to the ex. too. I'm not arguing with either of you I just want it to be clear that you do not have to add or subtract fuel to the polaris efi bikes when making mods to them. I could only wish that we coudl reprogram the ecu's thoguh to raise the operating rpm's and change the timing curve.

 

Our local Chevy dealer said that the oil will foul a injecter

 

Our local Chevy dealer said the oil will foul a fuel injecter

 

Where did that come from???????????