hi Chris from Dynojet here in this video we're going to talk a little bit
about deceleration popping what causes it what it is and we'll discuss a few
things that you might be able to do to reduce it deceleration popping is
commonly misconceived as a problem with the bikes air fuel ratio a lot of people
feel that their power commander map needs an adjustment if they notice
deceleration popping and it's not always the strongest indicator that your power
commander map needs adjustment for example most metric bikes are going to
have a pair valve or a clean air injection system that is injecting fresh
air into the exhaust system that promotes deceleration popping on this
2012 r1 I've removed the fuel tank in the air box to give you a demonstration
of what the pair valve is now deceleration popping occurs when there's
unburnt fuel in the exhaust system particularly on a metric bike most
metric bikes you're going to find this system here which is a pair valve or a
clean air injection system this system is here to pump fresh air from the air
box into the exhaust ports of the cylinder heads to make the mixture in
the exhaust right for ignition so as long as this system is on the bike and
active deceleration popping would be considered normal a lot of people might
notice a lot more de sel popping after fitting their bike with an aftermarket
high-flown exhaust system on a stock exhaust system perhaps with a double
walled exhaust pipes or catalytic converter or extra baffling in the
mufflers there's going to be decel popping present but it's a lot more
noticeable with an aftermarket exhaust system with a high flow open baffle also
very often when exhaust systems get changed the exhaust gaskets at the
cylinder head get reused the stock gaskets get reused and it's generally
good practice to replace the exhaust gaskets here whenever you're changing
the exhaust system also some aftermarket exhaust systems will require a special
type of gasket here you certainly want to make sure you also don't have any
leaks downstream much like the pair valve would introduce fresh air into the
exhaust an exhaust leak will also do basically the same thing in
cause de sel popping happen also further downstream we the exhaust system we want
to make sure we don't have any leaks at any joints like right here so now that
we've covered those two topics we can also show you what you might be able to
do in your Power Commander map to reduce popping so here I am inside of the power
commander five software I'm currently connected to the Power Commander five
I'm going to hit get map to retrieve the current map inside of my power commander
and I'm going to look at the fuel table so here in my fuel table while
decelerating I'm going to be in the zero percent throttle column my throttle is
closed whenever I'm decelerating but my throttle is also closed when I'm idling
so I don't want to mess with the idle fuel mixture so I'm going to leave the
500 to 1500 rpm cells alone I'm only going to make modifications from 2000
rpm all the way down to redline that's where I'm going to be at in my power
commander map file when I'm decelerating so here in the deceleration region of
your fuel table you might find that if you add more fuel you'll reduce the
temperature of the exhaust gases by adding more fuel you'll make the mixture
bit richer so that it doesn't have an appropriate mixture to ignite in the
pipe and burn if I'm going to add fuel I might start with a 15 and after I put my
new diesel fuel change in I'll hit sin map for it to go into the power
commander if I find that the popping is reduced but still there I might increase
this value 5 increments at a time so with 15 getting better but still popping
a little I might try a 20 and send that in so you want to increase this in
increments of 5 until you have a desirable effect on your diesel popping
the problem being if you go over 40 on this you might start to notice a severe
loss of fuel economy you will be using extra fuel under deceleration to try to
reduce this popping so increasing fuel 40% or more here is going to start to be
a it's going to start to affect your fuel economy negatively if we're trying
to overcompensate for fresh air in the exhaust we might try go
going the opposite direction we might want to try negative fuel changes here
if I'm going to subtract fuel I might start with a minus 60 if a minus 60
helps but still need to go a little bit further you can go minus 70 or minus 80
- 90 you can go all the way to a minus 100 and basically what that will do is
that will shut the fuel injectors off completely while you're decelerating
this is also a common strategy used and a lot of the stock ECU is out there a
lot of times you'll see that the bike shuts the injectors off under
deceleration no matter what you do in your Power Commander map the problem
with shutting the injectors off a lot of times is that when you roll back into
the throttle and the injectors come back on you might notice that the power comes
back on sort of abruptly which can be problematic for a lot of for a lot of
riders also if you have a Power Commander that has ignition control or
an additional ignition module accessory added on to your Power Commander you
might find a desirable effect by making this modification in the same range of
your ignition tables if you increase timing overstock let's say I add five
degrees of timing in the D cell range you might export the fuel in the engine
sooner thus allowing for a longer burn of the fuel in the engine so that less
unburnt fuel is actually released into the exhaust and that might have a
desirable effect but again that's only capable if you have ignition control
capabilities inside of your powered commander tune so to reiterate decel
popping can be perfectly normal in some circumstances it's more of an annoyance
than anything you certainly want to try to reduce fresh air from coming into
your exhaust system as much as possible to help reduce the effect and finally
you can make it a justment to your power commander map like this to help reduce
it