So I've read through a bunch of posts, and still don't see an answer, so I'll post.

I'm using the TTS Mastertune to try to tune out a decel pop.

I installed new Rush 2" slip-ons on my 2008 Dyna Superglide Custom (FXDC). The rest of the bike is stock.

I had quite a bit of popping, so I checked HDForums and learned that exhaust leaks are usually the problem. I did indeed have leaky joints, so I used the ultra copper silicone and reinstalled. I couldn't find any more leaks. Had it to the stealer today for 5000 mile service and had them check too - they report no leaks.

I've still got a pop and a rumble. I've gone up and down the AFR scale on the 20 kPa column and I've played with the Decel enleanment. I have reduced the problem, but not eliminated. No matter how rich I made the mixture, the problem didn't get better. It's not too bad at 14.5 AFR and a decel enleanment of 0.46 multiplier.

But, I still get a very pronounced pop an shifts about 10 percent of the time. I roll off the throttle simultaneouly pulling the clutch - when the engine spins down, or just when I am rolling back on the throttle, I get a pop.

If I downshift without blipping the throttle, no pop, but I get a rumble (maybe light pops) almost all the way down the rpm range.

I can live with the rumble, but I don't like the pop.

I've chased the AFR down and back up the scale from 14.5 down to 11.0 and back up. Not a big affect, but seems best very lean.

Of course, the stealer says this is normal for slip-ons.

Any suggestions? I can't go any more lean, but I could increase the decel enleanment more.

I could go more rich than 11.0, but it just feels like I'm groping around in the dark - I've remapped a couple dozen times trying all these different AFR values. (At least I'm taking a nice ride in-between the re-maps.)

Wayne

 

You still have the factory AC? I don't know if any of the TTS base maps were made with the factory AC in mind. Not an expert, just pointing out a potential issue.

 

Yeah - adding parts as the budget allows.

Since writing this, it has dawned on me that my Vtune session occurred after the first install of the new exhaust - before I realized that there was a leak at the slip-on joints. There was a significant change in the 0 Throttle VE column, so I'm going to retune now that the leaks are corrected. We'll see if that makes any difference.

 

You can manually change the VE tables to reduce the fuel more- leave the AFR at 14.5 in 20 KPA column, but decrease the VE numbers at the RPM of issue in the 0 throttle position column. You may also need to do this in the 2% column as well, to smooth the differences between columns. Also look for drastic differences in adjoining areas of the VE tables- that will induce issues. Some bikes like leaner, some like richer, to reduce decel pop. If leaner doesn't help, you can richen the area by increasing the VE# at the area of issue.
HTH
Robin

 

So, I've gone through the Vtune process again, and gone up and down the scale on AFR in the 20 kPa column again with no luck getting rid of the pop. I can definitely make the situation worse, but I can never improve it enough to get rid of the popping.

I've checked for leaks again too, with no leaks.

I'm wondering if Rush 2" are just too free flowing for the 96" stock engine. Maybe it is time to downsize to the 1.75"?

 

I have the same problem 07 dyna lowrider with rush 2.0 and the PC-V I have gone up and down the fuel table. as soon I went in - side of the table leaner side I had some backfire. I cant get rid of the pop mine does it on up shift that is what bugs me the most

Tim

 

Here is a thought and something that was successful for me with a SERT on a 2007 Street Glide.

If you are happy with the performance other than the decel pop, try a different base calibration file that is similar and cut/paste each table that you have tuned into the new prospective calibration. Then load that calibration into your bike to see if the decel pop you are experiencing goes away.

As in my example - I was running the 176pz calibration (dyno tuned and re dyno tuned) and always experienced a decel pop when I released the throttle between 1700-2400 rpm which i could make move between these ranges but never go away. I switched it to the 176ae version and WAHLA no decel pop. I took my new calibration file to the dyno and had it tuned once more and for the most part it was right on since it had been tuned before. 10,000 miles later I have not experienced a single pop.

Steve Cole (the writer of the software for the SERT and TTS) confirmed that within the same cc motor there really is not a reason to seperate them by bike model family. So the Touring, Dyna and Softail maps are interchangeable.

Why does this work? Well apparently there are several internal tables that have been set up that have slight variances. When these were originally created the tuning strategy for all of the tables went down to a single individual who's job it was to tune for that particular application and there may not be a consistent way this was done.

I believe you will find that if you try this you will eliminate the decel pop and have your bike run the way you expect.

 

I can't thank you enough TickTock. I was running the AE176-002-B1.MT7 calibration, with my own Vtune adjustments, and the Rush 2.0 pipes are the only modification so far. I spent the last week and half changing settings with the TTS MasterTune and just couldn't get to a reasonable level of decel pop on the Rush pipes.

Based on what you wrote, I copied my tables (all of them) from my AE176 file to the QD176 calibration. Problem solved! I just came back from a good hard ride and I got one slight pop on one hard decel (no pops on a bunch of good hard decels). Before the change, it was burbling on every decel and popping several times per decel.

It is hard to understand why this makes a difference - it is air in, fuel in, and spark at the right time - I didn't change the spark timing or the AFR, nor the decel enleanment or closed throttle spark; everything was the same except the file I started with. Night and day difference.

Thank you again. If you're ever in KC, look me up and I'll buy you a beer or a good stiff drink.

Wayne

 

I'm glad it worked out for you. One day when we both have lots of time I will give you the whole story on how I finally got that answer. It took me months but with the help of ShovelHead Bob and a few others I decided to try what I wrote to you. After trying to get a straight answer from the MOCO back when it was a SERT I finally just gave up and made the adjustments. When Steve Cole started posting here he confirmed what I wrote to you. I bet now if you did a vtune you could tune it all out.

good luck and you bet if I am in KS I will take you up on the beer!