popping / backfiring after installing Arrow full system on 05 S4R

[♣ McKraut ♣]

i put arrows on my S4R (2005, stock ECU, 21k miles, OEM paper air filter, airbox unmodded) about three months ago...and at first noticed really no popping.  now, though, when i decelerate hard, it's popping / backfiring a LOT.  i'm not big on going the power commander route (i've done it once before on an 05 S2R...but my local dealer *hates* them)...what other options would i have though?  i don't have the $$ for DP ECU...  would a fuel trim adjustment on my stock ECU by my dealer be sufficient?  i'm not going for max hp/torque or the best dyno curves...just a bike that's running well and not popping.  any suggestions?

[ducpainter]

More likely you have an air leak at a connection.

Doesn't the S4R use a gasket in the pipe near the header to cyl connection?

[♣ McKraut ♣]

yes, IIRC.

i can check again for leaks, but the last time i checked things seem pretty well free of exhaust leaks.

[ducpainter]

yes, IIRC.

i can check again for leaks, but the last time i checked things seem pretty well free of exhaust leaks.

I seem to remember that gasket being problematic.

[2CardDuc]

I had the same problem w/mine after installing Desmo Spark mid-pipe, cans, PCIII, modded airbox, K&N filter and custom dyno.  However, the backfiring on decell did not start until after about 1K later or so.  I found cracks in my shorty headers.  Did a little a little welding, installed new gaskets and allot of high-temp. RTV to resolve the problem.  10K later and it still pulls strong w/no backfiring whatsoever.       

[DucHead]

I had the same problem w/mine after installing Desmo Spark mid-pipe, cans, PCIII, modded airbox, K&N filter and custom dyno.  However, the backfiring on decell did not start until after about 1K later or so.  I found cracks in my shorty headers.  Did a little a little welding, installed new gaskets and allot of high-temp. RTV to resolve the problem.  10K later and it still pulls strong w/no backfiring whatsoever.       

+1 on the cracks on the shorty header on the horizontal cylinder...the flange on mine was nearly hanging off!!

Rameses welded it, but I could never get rid of the leaks from the union of the header and the midpipe.

Oh, and those metal "sponge" gaskets suck ass!

[Smokescreen]

I'm thinking it'd have to be a lot of backfiring to be problematic.  Backfires occur when unburnt fuel ignites in the header.  Some manufacturers even have a pet valve in the head that introduces clean air into the exhaust to ignite unburnt fuel.  And in that way, most bikes backfire right outta the box, albeit with restrictive enough mufflers that the burn is contained and rarely heard.  Pet valve tend to fail in the open position causing more backfiring over time, although I'm pretty sure ducati doesn't use these, so that doesn't matter for our purposes.

I seem to be offering this a lot lately but...  Have you tried replacing the plugs?  Even slightly worn plugs can be inefficient, causing an incomplete flame front, and more unburnt fuel in the header...  And you can keep this cheap, and just buy normal "house" plugs for around $2 each.  For the same cost, you can go a step colder (hotter? i can never remember which is which and I think it differs between manufacturers) so that your plug maintains temp better.

As a side note, I'm leaning toward standard plugs due to unsettling stories I've heard lately.  GM put out a technical bulletin asking their dealers NOT to install Bosch Platinum plugs in their cars.  Two people I know had power loss issues resolved by replacing their BP plugs with "house" plugs at a quarter the price.....  It seems the platinum plugs were sort of melting into a filament (very fine) that stretched the gap, causing shorts.

I've run iridium plugs successfully in my Subaru and in my S2R, but I'm pretty sure there were no gains on the bike that made spending the extra coin worth it.

Just my .15 cents

[♣ McKraut ♣]

well, as the temps are getting hotter here...the popping has seemed to increase to an unacceptable level.  i'm still running the stock airbox lid and stock paper filter...but hard decel is getting some LOUD and very sharp pops...and lots of them.  it's to the point where i don't want to downshift, and instead just clutch in and grab front brakes for every stoplight, which is a habit i don't want to get in.  and actually sometimes when i'm at a cruising RPM, if i back off even *slightly* on the throttle, i will hear popping.  this to me is unacceptable.

it's just recently had the throttle bodies balanced, and valves checked, as well as belts replaced.  i also had him try to seal up the exhaust even more...so this shouldn't have much if anything to do with any leaking in the exhaust pipes.  what options do i have at this point?  i know they can adjust my trim a little bit at least on the stock ECU...would that be sufficient?  there's no way i'm throwing down for a DP ECU... i guess my only other realistic option would be a power commander...but i'm not very crazy about them, either.  i'd rather not have additional hardware on the bike; the scorpio alarm is enough i think.

suggestions?  it's getting embarrassing...  i don't want people on the road to think that's what Ducatis sound like....popcorn.

[GraGra]

i'm not sure this will help, but I will share my experience with my 2006 S2R1K.

It's a Euro spec bike - which apparently has a different ECU than the US ones.

I installed a full Arrow system - and then took it to the shop to have the TPS re-set, and the airbleeds adjusted. Bike was surging somewhat even before the exhaust install.

With the new system in, the bike felt rought - and was popping a lot on decel.

According to the shop, the adjustments were difficult to get right - but eventually I got the bike back, - with the lambda sensor unplugged (there is a bung hole in the Arrows mid- for which arrow supply a nut to close up.

The bike was running much better - really a vast improvement.

So to summarise - this was standard box and filter, full arrow system, sensor unplugged - and the TPS and air-bleeds adjusted by Ducati mechanic.

I happily rode the bike like this for about a year, there was still some intermittent popping on decel - but nothiig like before - and I only really noticed this during track days.

I have however been interested in getting the DP ECU - to really fix things up and so I could open up the airbox, however coming up with the cash for that is tough to do. And having the standard one reflashed to DP spec - while an option, is difficult for me here in THailand.

I ended up opening up the box, and expected more popping. It didn't happen. If anything, the bike seemed a little more responsive at very low RPM.

I then purchased a FATDUC o2 manipulator for about 100 bucks. Now, there is almost zero popping - I simply re-attached the o2 ensor to the mid-pipe, set the manipulator to the rich setting - about 13.1 - left the airbox open, added a K&N filter even.

Bike is now still ruinning smooth at low constant throttle - no surging, the engine response at low-RPM, let's say 2500- 4500 is very smooth, and the bike runs smoother in top gear.

I will occasionally get a small pop - more like a fart sound - but nothiig like when the exhaust was first installed - and I feel that the bike is running as good as it can without further fuelling or mapping adjustments which are available through purchase of the DP ecu or your standard ecu re-flashed to DP ECU spec -or other means.

Again, not sure if this will help you, but I have just outlined the process I went through with my bike to get the best solution with the standard ecu and a full arrow system.

At a minimum, I would expect that you would see some improvement by unplugging the lambda sensor and having the TPS and airbleeds properly set up.

Cheers...

[duccarlos]

DP ECU, FATDUC, PC. Just suck it up and buy something.

[♣ McKraut ♣]

well... O2 manipulators don't exactly help....  it's an 05 S4R, so there's nothing to plug it into.  and DP ECU is definitely out... i'm not paying that much $$ just to eliminate popping.  i would think about a PCIII, but the unit is like $300 plus at least $200 to tune/map it.  so still a bit pricey in my eyes just to eliminate some popping.  i don't care about the best power/torque curves, just want something that runs well, and doesn't sound like i'm hurting it every time i come off the throttle.  and to that end...is this a harmful condition over the long term?  i've heard people claim that it is, but i wonder.

[Speeddog]

Go for the trim adjustment.

[♣ McKraut ♣]

Go for the trim adjustment.

yeah, that's the thing i was hoping would be viable...and cheapest, and save me having to install another add on.  they don't even have to spend all that much time on it, just so that it's no longer the orville redenbacher express...  i'll give them a call and see if they can ballpark a price for me.

[♣ McKraut ♣]

well, that was fast.  according to the tech i just talked to at AMS, there may or may not be any adjustment to be had on it...but he said i could bring it in and put it on the dyno and find out...  wtf, either there is or there isn't.  i had always heard that there's some adjustment to be had, though.  assuming that there is...would it be enough to eliminate a very lean condition?

[2CardDuc]

Closely check the flanges on your shorty headers for cracks.  The best tech, power commander and dyno won't correct the decell backfire if those headers are cracked.  Mine sounded like a rat rod with straight headers before throwing the welder to them...