Tmax and backfiring

[mayor]

sprocket,
I'm not running a tach on my T-max bike either, so just to give you a reference to RPM on your bike  in 5th gear - 48mph is around 2k, 60mph is around 2.5k and 70mph is around 3k.  

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?

they're telling you that in case the changes make drastic differences in air flow (fuel requirements).  my guess is the t-max will be able to account for most changes well enough not to worry about your learned offsets, besides it didn't look like the base fuel maps were altered that much on the map you attached.  

I played with your map a little, I attached one with the changes I made.  It was easier than trying to explain what to try.  I readjusted the timing a little, and I changed your afr to richen up slightly at decel.  try this and report back on how it works.  

[attachment removed after 60 days by system]

[sprocket99]

sprocket,
I'm not running a tach on my T-max bike either, so just to give you a reference to RPM on your bike  in 5th gear - 48mph is around 2k, 60mph is around 2.5k and 70mph is around 3k.  

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?

they're telling you that in case the changes make drastic differences in air flow (fuel requirements).  my guess is the t-max will be able to account for most changes well enough not to worry about your learned offsets, besides it didn't look like the base fuel maps were altered that much on the map you attached.  

I played with your map a little, I attached one with the changes I made.  It was easier than trying to explain what to try.  I readjusted the timing a little, and I changed your afr to richen up slightly at decel.  try this and report back on how it works.  

Thanks! I'll try that tomorrow. Hope it doesn't rain. I don't make any changes to the muffler, just one variable at a time,  unless you think otherwise.

[mayor]

one variable at a time is probably best.  I'm not a tuner and I didn't stay in a Holiday Inn last night, so we'll see how that works.      btw....I stayed in a Comfort Inn last night, so hopefully that doesn't affect the outcome.   

[sprocket99]

one variable at a time is probably best.  I'm not a tuner and I didn't stay in a Holiday Inn last night, so we'll see how that works.      btw....I stayed in a Comfort Inn last night, so hopefully that doesn't affect the outcome.   

What might affect the outcome is not where you stayed, but what you were doing while you were there.

[7hogs]

Bob always has something good to say

[sprocket99]

sprocket,
I'm not running a tach on my T-max bike either, so just to give you a reference to RPM on your bike  in 5th gear - 48mph is around 2k, 60mph is around 2.5k and 70mph is around 3k.  

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?

they're telling you that in case the changes make drastic differences in air flow (fuel requirements).  my guess is the t-max will be able to account for most changes well enough not to worry about your learned offsets, besides it didn't look like the base fuel maps were altered that much on the map you attached.  


I played with your map a little, I attached one with the changes I made.  It was easier than trying to explain what to try.  I readjusted the timing a little, and I changed your afr to richen up slightly at decel.  try this and report back on how it works.  

I loaded the map you sent. Now, I wasn't clear about the process so I loaded it as TMax instructs to do with a new map. Nothing I could find in the manual described installing a modified map, so I hope I didn't destroy anything of value.
Anyway, got in about a 40 mile ride and 90% of the decel pop was gone, but the backfire persisted. I could replicate it in 2nd gear at about 30-35 mph when rolling off the throttle. I can ride some more to see if auto tune will compensate, or I can try to plug that left muffler, or make some more changes, whatever you think.

[FLTRI]

.... or I can try to plug that left muffler, or make some more changes, whatever you think.

I would use the plugged left side for the lasr resort. You may get rid of the decel pops but at the cost of power. Contrary to popular opinions, the "Y" pipe system works well for mild builds.
Bob

[mayor]

I loaded the map you sent. Now, I wasn't clear about the process so I loaded it as TMax instructs to do with a new map. Nothing I could find in the manual described installing a modified map, so I hope I didn't destroy anything of value.

no worries...I modified the map that you posted, so it was the same as what you had.  


I'm at a loss on the back firing.    

is it any worse with the adjusted map?

does it only happen at heavy decel?  

it may be an issue with the connected pipes adding afr "noise" and confusing the autotune.  You may need to get a base line dyno run to see what is going on.  

[Admiral Akbar]

I played with your map a little, I attached one with the changes I made.  It was easier than trying to explain what to try.  I readjusted the timing a little, and I changed your afr to richen up slightly at decel.  try this and report back on how it works. 

Man what a fugly map... Good thing no one wakes the throttle wide open at 1000 RPM..  Max

[sprocket99]

The backfire is worse, much louder sometimes and more frequent. It's at heavy and moderate decel. I easily can make it happen at 30-35 mph in 2nd, for example.
The dyno is an option but from asking around the only decent one is about an hour and a half from me so I wasn't ready to make the leap. Have to think about that.

[mayor]

where are you located? 

[sprocket99]

between Philly and Wilmington

[mayor]

max, what rpm range is 30-35 mph in 2nd? (I'm 400 miles from my bikes right now )

[7hogs]

Just a thought but I would re initialize the unit by turning your power switch that is explained in the documentation and also disable the fuel cut on decel.

Once you have done this ride the bike and let it make some adjustments and once the fuel offsets get balanced out and you still are issues re run your Auto IAC.

Also very basic but make sure your muffler clamps are tight.

[7hogs]

PS....................... the TMAX will take some time to balance out

[sprocket99]

Thanks for the idea. I should be able to do that today. Actually, I replaced my clamps a couple of weeks ago and sealed them with hi temp copper silicone just to make sure.

[sprocket99]

Great news! OK, I reinitialized and disabled the decel pop setting. Maybe I should have just gone with the initializing first, to avoid 2 variables. Anyway, it is MUCH better! The noise I get is more subdued, more like a loud fart than a .38, and much less frequent.
I was able to narrow it down to where I can duplicate the range:
In 2nd gear, if I let off at 40 mph, it will pop at about 34 mph.
In 3rd, letting off at 50, will pop at about 43.
So if we can determine what RPM this translates to, that would help, right?

[sprocket99]

I have these:

1. The attachment is an Excel spreadsheet and should work to narrow the rpm range.  After that, I need your help.
Mine is an '07 6 sp.

2. This is also good- http://www.bigboyzheadporting.com/Gearratio.htm




[attachment removed after 60 days by system]

[mayor]

based on the information you posted, looks like 2.7-2.8k is your problem area.  so what are you experiencing now- a back fire or a pop?


if it's popping, try adjusting the 2816 rpm timing map a little more in the light tps area (match your map to the red circled area below):



if you think it's backfiring, try cutting some fuel away from the light tps ranges of the 2560, 2816, and 3072 afr maps (match your map to the red circled area below):

[sprocket99]

based on the information you posted, looks like 2.7-2.8k is your problem area.  so what are you experiencing now- a back fire or a pop?


if it's popping, try adjusting the 2816 rpm timing map a little more in the light tps area (match your map to the red circled area below):



if you think it's backfiring, try cutting some fuel away from the light tps ranges of the 2560, 2816, and 3072 afr maps (match your map to the red circled area below):

It's hard to tell whether it's a pop or backfire, but I'll adjust for pop first. Since I disabled the decel pop setting it might be that. If not, I'll cut fuel in those areas.
mayor, thanks for your work on this. I will report back.

[mayor]

Just a thought but I would re initialize the unit by turning your power switch that is explained in the documentation and also disable the fuel cut on decel.

good catch on disabling the fuel cut function 7hogs.  I never gave that a thought.    I prefer not to use that function, since most of the time timing adjustments can limit the need to use it. 

[sprocket99]

Tried the decel pop adjustment, didn't seem to make much difference, so I adjusted the map for backfire. (I didn't leave in the adjustments for the pop.) It didn't go away, but is less consistent. Shows up at 2900-3000 rpm according to the chart. I was only able to ride about 30 miles, so I don't know if it will improve with more riding. Or, if you think more adjustments are in order, I'm good with that also.
Since my setting for decel fuel cut rpm high was set at 2784, I put it back to the default of 2400 rpm, and the backfire was occurring at a lower range, about 2600-2800 rpm. Especially in 2nd gear. Don't know if it's significant, just saying.
Regardless, with your help we've made more progress in the last 2 days than in the last year, so I am real happy with the results so far.

[7hogs]

Great news! OK, I reinitialized and disabled the decel pop setting. Maybe I should have just gone with the initializing first, to avoid 2 variables. Anyway, it is MUCH better! The noise I get is more subdued, more like a loud fart than a .38, and much less frequent.
I was able to narrow it down to where I can duplicate the range:
In 2nd gear, if I let off at 40 mph, it will pop at about 34 mph.
In 3rd, letting off at 50, will pop at about 43.
So if we can determine what RPM this translates to, that would help, right?

If that worked leave it and let it adjust itself......... now if you apply your learned offsets it will adjust thing you need plus things you do not like the pop and it will go away as it re adjust the stuff it took away................... ride it and leave it alone for awhile and see what happens........ I have been working with the TMAX since 2006 and there are more things to understand and I learn more every day

?? Doe the bike pop while it is warming up when you ride it? If know I know what you need to do.

[7hogs]

Looked at your MAP and one thing I would do is go to

Air Fuel Ratios Curves,

AFR Correction vs Engine Temp, Go to  226 degrees AFR correction 3.515 hit the L key, go to 401 degrees change it to 3.515 and hit the L key and it should draw a straight line across and if it get better or goes away you know you are on the right track.

Let me know if that helps but looking at your curve there seems to be to lean for my taste.

[sprocket99]

Great news! OK, I reinitialized and disabled the decel pop setting. Maybe I should have just gone with the initializing first, to avoid 2 variables. Anyway, it is MUCH better! The noise I get is more subdued, more like a loud fart than a .38, and much less frequent.
I was able to narrow it down to where I can duplicate the range:
In 2nd gear, if I let off at 40 mph, it will pop at about 34 mph.
In 3rd, letting off at 50, will pop at about 43.
So if we can determine what RPM this translates to, that would help, right?

If that worked leave it and let it adjust itself......... now if you apply your learned offsets it will adjust thing you need plus things you do not like the pop and it will go away as it re adjust the stuff it took away................... ride it and leave it alone for awhile and see what happens........ I have been working with the TMAX since 2006 and there are more things to understand and I learn more every day

?? Doe the bike pop while it is warming up when you ride it? If know I know what you need to do.

It does pop while warming, gets better after awhile. I will look at the AFR correction and try what you say.