Re-Map after exhaust change

[SlfAwre]

So I searched a bit but not sure I found what I was hoping for:

Of course, now that I have changed from the stock exhaust, I will likely benefit from some changes to the fueling.  Bike has all the characteristics of too lean-popping on decel, snatchy throttle and so on.

This winter I'll get rid of the air injection/charcoal canister and install some block off plates.  Maybe some kind of sporty air filter too but will likely not go through the effort required for a de-cat on the 8 gen.

What's the best way to adjust the fueling to suit? Power commander, re-flash ECU? What's this Rapid bike thing?

 

From experience, I undertand the concepts but I know very little about how this is done nowadays.  Can anyone who has done it report on specifics and how well it worked?

Of course, this is all for closed course use..

Thanks!

 

[smoke4ndmears]

If you just went slip-on (which is most likely, since there aren't any headers out there I don't think) getting rid of the air-injection and adding block off plates should sort your bike out. I installed block-off plates and all of that on day one, along with a slip on a week later. Never have had any surging or popping. 

[MrGrumpy83]

Is there any info out there for how to do the block-off plates and removing air injection? Be interested to learn more about these mods and what effect they have. Mine's similar to the OP - bit snatchy and lots of popping on decel and if I could clean that up it'd be nice :)

[fink]

Simply remove the system and block of the holes.

[MrGrumpy83]

Where would one find this system? What does it look like? What do you block up the holes with? What other benefits, ill-effects, etc. etc. does it have?

 

Maybe a simpler question to ask is - is what's being referred to otherwise known as the PAIR mod? And in that case - is it even relevant on the 8th gen?

[SlfAwre]

2 hours ago, MrGrumpy83 said:

Where would one find this system? What does it look like? What do you block up the holes with? What other benefits, ill-effects, etc. etc. does it have?

 

Maybe a simpler question to ask is - is what's being referred to otherwise known as the PAIR mod? And in that case - is it even relevant on the 8th gen?

I think it's the same thing, and yes the 8 gen has all the air injection stuff.  There's a how to somewhere on here I think. Holes are blocked w special plates that are somewhat bike/model specific.  I bought these:

 

http://www.pmc-usa.com/2014-2015-honda-vfr800-interceptor-ais-smog-block-off-plates/

[MrGrumpy83]

Thanks, I'll have a look and see if I can find the thread on it. I know I've seen it talked about a lot on 6th Gen bikes but don't necessarily recall seeing it for the 8th Gen.

[fink]

Have got to say I have never heard of it being done on the new model.  Hence my reply which is basically what is done on earlier models. 

 

Op doesn't say which can he has put on. 

 

 

 

[jhenley17]

Mine pops a lot on deceleration, I might have a go at it next time I plan on taking things apart. I'm still very dissatisfied with my VTEC transition, so I'll be putting a PCV in some time this winter.


Sent from my iPhone using Tapatalk

[Bent]

Deceleration popping can be caused by not enough back pressure.  Be careful what you start changing before considering this.  As someone else said, we don't know what you changed.  

[jhenley17]

That could be, but with a cat still in place, I think it's unlikely. I'll probably run a preset map first and go from there.


Sent from my iPhone using Tapatalk

[SlfAwre]

9 hours ago, Bent said:

Deceleration popping can be caused by not enough back pressure.  Be careful what you start changing before considering this.  As someone else said, we don't know what you changed.  

 

I didn't mention the type because I didn't think it matters that much?  But anyway, it's a Yamamoto slip on (a Japanese brand) though it seems like all the slip-ons differ mainly in cosmetics-other than some have a removable baffle, which mine doesn't.  It's straight through with larger diameter pipe than the stock stuff.

Didn't change anything else and the cat is still in there, so like someone said it's not likely far off but I have to say it's a noticeable difference compared to before and not in a good way. 

[fink]

A bigger bore will Deffo decrease the back pressure so affecting the performance. 

 

 

[Mohawk]

With the cat still in place there will be little difference in the back pressure as most is caused BT the cat. I assume you also have the stock O2 sensors in place, so no change to the ECU's fuelling. As stock to meet emissions regs these bikes run pretty lean.

a quick fix would be to disconnect the O2 sensors which will force the ECU into open loop emergency mode, so it riches the mixture. You will have an Fi warning light, but try that first. If the popping goes away then you know it's a too lean condition.

 

don't leave it that way as too rich Weill kill the cat after a while, but it's a quick test. If you are happy with it after the test & don't mind Killing the cat, then just add ONE O2 eliminator to one O2 sensor connector on the harness side & the Fi light will go out. You can use a resistor for this, just search for details. Job jobbed.

 

YMMV literally as running richer will pull down your MPG ! 

 

Have fun.

[smoke4ndmears]

Just remove the PAIR system and install block-off plates. It is the primary source of all of that oxygen that is making the mixture in your headers lean. By design the extra oxygen it provides is there to burn off any unburnt fuel from the combustion process. The OEM muffler is much better at masking the popping, so much so that you probably never noticed it happening before you changed to the new pipe. 

[jhenley17]

How true is it that the bikes run pretty lean stock? This is the first FI bike I've owned, and that little bit of supposed common knowledge is the main reason I want to install a PCV before messing with anything.


Sent from my iPhone using Tapatalk

[smoke4ndmears]

Everything runs lean. Emissions standards more or less require it.

[SlfAwre]

13 hours ago, jhenley17 said:

How true is it that the bikes run pretty lean stock? This is the first FI bike I've owned, and that little bit of supposed common knowledge is the main reason I want to install a PCV before messing with anything.


Sent from my iPhone using Tapatalk

 

 

10 hours ago, smoke4ndmears said:

Everything runs lean. Emissions standards more or less require it.

 

I think it's safe to say it's pretty lean from the factory to get by all the emissions requirements-I don't have anything specific to back that up other than the people I know who know about tuning modern FI bikes seem to agree, and all the aftermarket stuff adds fuel to get whatever drivability and power gains can be had.  It's just a question of how far to go.  With this bike and the dearth of aftermarket support for it, I'm not going very far. 

I think the first step is to take off the air injection stuff, step 2 would be a change to the fuel map (power commander or whatever).  A de-cat would be great, (and definitely reguire a re-map) but it looks like a real chore on this bike.

[smoke4ndmears]

Fortunately the bike fuels smooth enough from the factory to not particularly need re-mapping, nor is it down on power from a weak map. Have had bikes that fall under both categories. Gains from mapping the RC79 seem to be marginal. 

[smoke4ndmears]

Where did you pick up the Yamamoto slip-on by the way?

[SlfAwre]

Here:

It's for the Crossrunner but I took a chance and turns out it fits perfectly, albeit w some modification to the undertray to fit the hanger.  There's some more info in the exhaust thread.

 

http://japan.webike.net/products/21837664.html

[CandyRedRC46]

Lot of common misconceptions out there about how the FI system and emissions systems work together, power commanders and popping etc...

I have a 6th gen, not an 8th, so I can comment on my 6th and assume that most of it carries over to 8th gen

 

The popping does not have to do with any mapping that a power commander will iron out. The popping only occurs, when the throttle is shut at higher rpms (aka over run) and there is an overly lean condition (15-20:1 plus AFR), where the mixture is too lean to completely burn in the combustion chamber and can accumulate in the exhaust port/ header/ catalytic converter/tail pipe/muffler and can combust there instead.

 

This overly lean condition can occur due to many reasons, most revolving around EPA regulations. One reason is the Pair valves that everyone knows all too well. The pair valves can be blocked off easily, so they are no longer letting fresh air into the exhaust system, to continue the burn outside of the combustion chamber. There is debate to whether or not they are needed to keep the catalytic converter happy.

 

The other reason for the overly lean condition on over run that causes the popping on decel is call the "Fuel cut". Fuel cut on over run is mandated by the environment protection guys, so that you are not wasting fuel and creating emissions when you do not need to. There is no reason in the eyes of non enthusiasts to be dumping fuel in, when you are trying to slow down, even if it makes the bike smoother and more enjoyable to ride. 

 

Basically when the throttle is closed, at certain speeds and rpms, the injectors are phased out or shut down entirely. This also accounts for a lot of the harsh on/off throttle transitions of newer fuel injected bikes (I believe even some late carb'd bikes shut the pump off on overrun), because the injectors are coming on and off, on top of the throttle being opened or/and closed. It is different in every gear, but on my sixth gen it is more prominent in gears 4/5/6th than 1/2/3, where in stock form there would be zero fuel on over run in gears 4-6th and then when down shifting into 3rd and continuing to engine break, the injectors would slowly begin to get phased back in and the popping would then begin to occur.

 

The fuel cut, isn't something that you can just iron out with a power commander, because even if you dump 50% more fuel in the 0% throttle column at higher rpms, 50% of zero is still zero... That is why experienced tuners do not touch the 0% throttle column. That is not to say power commanders aren't great at fixing the lean mapping symptoms of the factory fuel mapping, but they can't eliminate the fuel cut. The only way of eliminating the fuel cut is with an ecu flash, fuel cut eliminator or rapid bike's engine brake control.

[jhenley17]

I always attributed the popping to lean conditions, but I never knew what the PAIR valve did until reading in this topic. It's not as jerky on the low end as my carbureted 599 was, but I still want to enrich it a little, mostly because it nags at me knowing it's running lean, but also to hopefully help it run a little cooler and smooth my annoying VTEC transition.


Sent from my iPhone using Tapatalk

[smoke4ndmears]

15 hours ago, SlfAwre said:

Here:

It's for the Crossrunner but I took a chance and turns out it fits perfectly, albeit w some modification to the undertray to fit the hanger.  There's some more info in the exhaust thread.

 

http://japan.webike.net/products/21837664.html

 

Man, was the juice worth the squeeze? Looks great but $$$

[DriverDave]

56 minutes ago, jhenley17 said:

...but also to hopefully help it run a little cooler and smooth my annoying VTEC transition.

I think you're the first person to complain about the VTEC transition on an 8th gen.  Since it came out, that has been identified by most reviews as one of the main improvements over the 6th gen...myself included.  Other than a sound change, I think you really don't feel the transition like the 6th gen did.

Sent from my iPhone using Tapatalk