In the april '08 AIM, there is an article titled "S&S Quick Set Up Kit". It tells you that you can use an S&S duel air cleaner, and set of slip on mufflers to unlock 10hp, and 6ftlbs. of torque. I understand that well enough, but it also states that you do not need to touch the ECM. I quote "That's because the stock ECM, complete with O2 sensors, can readjust itself to the increased airflow in and out of the engine, thanks to the new air cleaner and exhaust as you ride." It also tells you to let the bike run for 15 minutes to allow the ECM to readjust to the new airflow levels after installation of said parts.OK, I've been told and read, that you need not touch the ECM, with an exhaust change. BUT...... I thought that if you changed your intake restriction (air cleaner)you would need to have an ECM flash at minimum, or install a PC-III etc. What gives?

 

Hogbob, I'm scratching my head over the same article. Also, it appears that, based on the dyno runs, the 10hp was gained simply with the AC alone. Changing the slip-ons had zero effect. If what the article says about the ECM self-adjusting after simple AC and slip-on changes is true, then alot of downloads may have been paid for un-neccesarily. Atleast if the only goal was to return the A/F ratio back to the factory setting of 14.7:1.

 

I'm scratchin' too!

 

I read it too! the gain came from the A/C only, the slip-on's didn't increase the hp/tq. and this was done at a HD shop too if I remember correct. they said that after they made a change they ran the bike for 15 minutes to let the ECM adjust. makes me wonder? I guarantee that alot of people just slap on a set of pipes and A/C and go riding, and as far as that goes, some say that the download only increases the rev limiter to 6200rpm and that it does nothing for the AFR ratio.......

 

The stock ecm can't adapt to pipe and aircleaner change without modification. It will be way too lean.

 

The "download" you are refering to is still street legal which is still too lean for my preference. The "download" is designed for HD STREET LEGAL PRODUCTS only.....so other types of pipes will probably product less than desireable results like decel popping. IMHO the download is a waste....put the money toward a fuel management system that ALSO ALLOWS for timing adjustments.

 

Joe Minton, in past articles,also did a write-up in American Rider on this very subject. He swore the ECM had enough "adaptive learning" to adjust to a stage I build without a fuel management system, BUT Joe reported no gain in HP/TQ. He reported the necessity of a fuel management system in order gain any HP/TQ.

 

That right there should have told him he was wrong. If you're flowing more air, and the ECM is adding more fuel for that air, how could you not get more power?

 

Assuming the motor does not have a rich induced miss, the stock ECU could be very capable of bringing the closed loop sections right back to 14.7 AFR It may also wind up adding fuel to the top part of the power band depending if the average Long Trem Fuel Trim found on the closed loop section of the map is applied to the entire map. Air filter and exhaust changes have very little effect in the idle and very low HP sections of the map as there is just no real air flow for restrictions to be a problem.

Remember most closed loop sections of any code gets really confused when there is a dead miss. Both narrow or wide bands have this issue. They will always find oxygen and add fuel trying to correct and burn off the o2 it found.

Bottom line is many small changes can be adjusted out by the stock ECU. If ithe stock ECU does not figure it out in a few 100 miles it may never figure it out and a tuning may be the only solution. Any system that removes the o2s has no way of helping you (or the dyno guy) out. Using the $70 resistor trick and keeping the stock ECU program may well be worth trying as a way to cheat the Harley Dealer Dyno Racket.

Any pipe / AC / cam change really needs to be checked out with a wideband up on top. A little too lean is tough to feel from the drivers seat. Way too lean is expensive.

Hope this helps

AW

 

I put Slip-ons, SE a/c, and SERT with the newest cal #78, so if the ECM has any "adaptive" learning it should be close to optimum, that cal says it is for "Race mufflers, SE a/c". don't have a Dyno guy close that I trust anymore so maybe I will be ok. bike runs fine no issues whatsoever........07 FLHX.