Hi Folks

I am looking at buying (and installing) a new V&H exhaust system for my 2015 Dyna WG. 

If I had the coin, I would be upgrading the air and computer at the same time. I will eventually get t o this.

Is it OK for me to upgrade the exhaust and possibly air intake without having to touch the computer?

 

Cheers

Stones

Pauly's right. They run way too lean from new so all you'll do is make it run a heap leaner.

That's the answer I was expecting.

What I cant understanding is why the hardware dictates the a/f mixture. I realise pipes will make the engine breathe better, but shouldn't the standard tuner dictate what goes in into the pots?

Stones,, Good to see your interested, and keen to understand the workings of the newer efi harley bikes.. You have spent a lot of coin on a 2015 bike, and you want to be satisfied it is performing as if should with the minor mods, (stage 1 ), you are installing , and also be satisfied that the longevity of the engine is not compromised .. There are many opinions on what to do, tuning wise, with a basic stage 1 upgrade.. There is the more expensive way, (buy an advanced tuner , and get it professionally tuned),, or,( buy an advanced tuner with a base map that is configured to your mods and flash it to your ecm),,, or the less expensive, ( buy a device/tuner that basicly richens up the air fuel ratio)... Plenty on the internet for you to checkout, and get your head around all the technical stuff ...
One thing all the experts agree on is, that stock bikes are leaner, and restricted than otherwise would be the case, because of epa requirements .
Throw in the mix, a free flowing exhaust, and and more air, and you run the risk of running more to the lean side, ie (more heat)...
Some tuners even recommend that a stock bike be tuned, ( maybe not on the dyno), so as to have the bike performing as if there were no epa restrictions .... We call all of this "the Harley Tax", that we have to pay...

Thanks Guys

Pauly is right again. The ECU relies on information sent to it from various sensors, this is done by varying the voltage sent back to the ECU and it uses that voltage for information. Once it gets that it can then use the inputted parameters to either make the mixture richer or leaner. The catch is the standard table it uses for compensation has a limited range, so if it falls out of that standard range it simply won't compensate. Some cheap car tuners only trick the ECU into thinking the engine is always cold, so the ECU richens the mixture the same as it does on cold starts. Needless to say that is not the best way! My advice is do the tuner before any other mods or at least the same time as the pipes. V&H pipes have fuck all backpressure as it is. As soon as you fit a tuner even with a "canned" tune you'll notice it is better and the rear cylinder won't get as hot. Good luck