Tmax and backfiring

[sprocket99]

Hoping someone here has an idea why my 07 Street Bob backfires on decel. Also has decel pop. I run a Tmax, V&H slip-ons with BCT QQ baffles, Big Sucker on a stock motor. The folks at Zippers have sent me several new maps since last fall and had me out to their shop in June. Did some retuning which got my mpg from 30 to close to 40 (if I’m kind to the throttle), but still backfires. It happens mostly on closed throttle after higher rpms, sometimes between shifts and is intermittent.
The last setting they had me change was to increase the high rpm fuel cutoff by 50 rpm at a shot, which now is at around 3100. I’ve checked for intake and exhaust leaks, even had my indy confirm, he could find no leaks.
Been riding off and on for 40 years, I do a lot of the work myself having worked in a couple of bike shops back in the day, but this is my first EFI. I’ve been told everything from “it’s just tuning” to “that’s the nature of the exhaust setup and live with it”.  I will live with it if I have to, but it still bugs me and I think that someone might have some ideas.

[Admiral Akbar]

Plug the left side muffler up some.. advance timing from 0 to 14 deg TPS all RPM ranges the pop occurs. Max

[FLTRI]

Plug the left side muffler up some..

Now there's some "sound" advice

[mayor]

.. advance timing from 0 to 14 deg TPS all RPM ranges the pop occurs. Max

here's a video that shows you a slightly different way of increasing timing for the T-max:
Tuning T-max: 1. Zippers Thundermax timing adjustments to limit popping and coughing at lower RPM's

[sprocket99]

Thanks, I'll give it a try tomorrow.  That video looks good, too.
Max, forgive my ignorance, but what do you mean when you say "plug up the left side"?

I have another question for now- when I link up there is a message to synchronize with the module because I guess the map on my laptop is not the one Zippers installed on the module. Is it necessary for me to save the module map on the computer, and if so, how is it done, just hit "save" when I exit the program? Just want to make sure I still have it in case I screw things up.

[05RKClass]

sprocket, I've been messing with my TMax more lately.  From what I understand, when you "sync" the module it reads all the learned offsets from the autotune process and stores them to your PC.  You should do a "save as" and create a subfolder where all the other maps are to keep this "new" map seperate from the originals.  I changed the date at the end of the file name to help keep things strainght for myself.  If you just do a "save", it will overwrite the original map.... whoops?!

[sprocket99]

05, that's kind of what I thought. All I've done with the TMax is make setting changes, never tweaked the timing, so this could be challenging. It doesn't help that I don't have a tach, but I guess I'm not alone.
I wonder why the techs at Zippers don't do these things that lots of you seem to take for granted.

[Admiral Akbar]

Plug the left side muffler up some..

Now there's some "sound" advice

Max

[sprocket99]

Plug the left side muffler up some..

Now there's some "sound" advice

Max

OK, I give up. I searched the forum and found nothing about how to plug a muffler, so please give me a little more info.
I did increase the timing as suggested, that video was a great help since I am aged. After one ride it seemed like the decel pop was greatly reduced but still got some backfire, so I guess it needs a little more tweaking. Any ideas? Unless it has to go through a couple more learning sessions.
I'm pretty sure I took the right steps to load the changed map and tried to follow the tuning manual but I get confused with the terms, not sure when or whether to save, write, clear, etc.  I realize it's routine for many of you, but sometimes I need to see the step by step process to initiate the changes. I don't mean to be a pain but I'm a novice at EFI tuning and would greatly appreciate if someone could walk me through it. BTW, thanks for everything so far.

[nc-renegade]

Have you enabled the Decel Fuel Cutoff setting under Basic settings?

[sprocket99]

Yes, it is enabled.

[mayor]

can you do a write learned offset, then "save as" onto your computer, then attach that file so we can see what you have so far?

[sprocket99]

I'll give that a try

[sprocket99]

Here goes. Hope this is what you want. If not, let me know.

[attachment removed after 60 days by system]

[mayor]

looks like the early rpm timing is plenty enough (maybe a little too much).  what did you change on that map, and what was there already (from Zippers)? 

looks like the afr was adjusted as well, did you do that or was that done by Zippers? and have you it on a dyno to compare afr yet?

where is your tps at idle?   

[sprocket99]

First of all, I didn't run the IAC auto correctly, I just redid that, if it makes a difference on what you see I can redo the file and resend.
I changed the advance several degrees to make a smoother curve and in each timing vs. TPS area advanced it another degree. Zippers had timing retarded at idle.
The AFRs were from Zippers.
And I'm afraid I don't understand your last question- TPS at idle. Obviously, this is new to me and I'm just starting to be able to wrap my head around the terms and procedures.
Let me know what you think.

[mayor]

sorry, what I was asking is where does your throttle position rest at idle?  when you are hooked up to the bike, open up the timing v. tps @1024, after you hit link and monitor.....you will see a vertical red line indicating throttle plate position.   

[sprocket99]

looks like it's around 13

[mayor]

ok, 13 sounds about right.  in what gear and at what speeds are you experiencing popping?  since you don't have a tach- pick one gear and check what speed the popping starts and when it ends. 

The AFRs were from Zippers.

was the afr adjusted when they had you to their shop in June?  the afr from 2k-4k looks funky.  they have the WOT adjusted around 12.1:1, yet they have the light tps afr around 13.8:1.  did they adjust this on a dyno?  I'm just trying to figure why they have the afr so rich at WOT.  If they needed to run it that rich to account for the wide bands not being accurate to a sniffer (dyno afr), then the light tps may be leaner than you might want as well.   

[sprocket99]

One instance of popping will occur in 3rd gear, from 45-50 mph.
I don't know if the AFR was changed in June, the tech spent about 2 hours on it and needed to move on to something else. He didn't mention it, but I didn't want to look over his shoulder while he was working.
No dyno.

[sprocket99]

Come to think of it, he did lean it out a bit so maybe he did adjust the AFRs.

[Admiral Akbar]

OK, I give up. I searched the forum and found nothing about how to plug a muffler, so please give me a little more info.

Without looking at the muffler itself it would be hard to say exactly what to do... I've heard of some adding a freeze plug inside the cross over pipe and plugging it off completely. I'd probably figure our a way to add some more restriction to the baffle..  Maybe a big washer welded to the baffle or a washer on a bolt so that you can turn it.. One of the first thing both mayor and I did was to convert the exhaust system from the crossover to a true duals.. While this may not make the best HP compared to a 2 into 1, keeps air from making it's way back into the left pipe..

I'd figure out some temporary way to plug the pipe so if it don't work it's easy to return back to original..

Max

[sprocket99]

Max
I'm using V&H slip-ons with BCT QQ baffles. I installed a short portion of the original baffle behind the BCT just to quiet it down a bit, this was a tip from the tech at BCT. What I might try is to fasten a perforated crumb cup, about 1.75" dia., which is a small sink strainer inside the end baffle. That should slow down the flow and I already have it, sounds easier than going into the crossover or fabricating a lollipop (there is already one large and one small one in the BCT). I'll see how that works for now.

[mayor]

One of the first thing both mayor and I did was to convert the exhaust system from the crossover to a true duals.. While this may not make the best HP compared to a 2 into 1, keeps air from making it's way back into the left pipe..

yep, I'm glad I listened to you too.  I think it would be hard for the autotune to tell what air readings are real and what readings are reverb.   did you look at the map sprocket attached?   I wonder if Zippers intentionally adjusted afr to account for the troubled area?

[sprocket99]

When I changed my baffles the tech at Zippers told me to clear the learned fuel offsets. Is this something I should do when I make any adjustments to the muffler?