Decat - ECU flash required?

[Ethos]

I intend to do an ECU flash - but will I hurt anything on a new bike by doing the decat first and ECU flash a bit later?

 

I also intend to open up the airbox a bit but I will wait on that until I have the ECU flashed.

[Toymaster]

I'm under the impression the factory MAP and sensors will allow for the removal of the cat and still have the fueling "correct".  On my T7 I did go with a piggyback engine management but with my research I did after, I believe it is unncessary, it did give certain benefits but not necessary.  On my Desert X I've removed the cat and did no programing changes, from all indications fueling is correct. 

[prowlnS10]

1 hour ago, Ethos said:

I intend to do an ECU flash - but will I hurt anything on a new bike by doing the decat first and ECU flash a bit later?

 

I also intend to open up the airbox a bit but I will wait on that until I have the ECU flashed.

2WheelDynoWorks near Seattle, USA has likely tuned/flashed more CP2 motors than anyone & promotes removal of the air box snorkel because it is restrictive to air flow & an ECU flash for 2 primary reasons:

1. to correct epa fueling & timing maps, particularly under about 5,200 rpm (the upper range of the epa mandated test cycle), regardless of any other changes to improve throttle response & add refinement, also includes lowering the the radiator on/off by 10 degrees.Their flash requires disconnecting the O2 sensor. ;
2. when desnorkeling or replacing the airbox lid &/or decating to compensate for increased airflow & less exhaust restriction.

Most oem ecu mapping would struggle to compensate correctly for increased air flow &/or decatting over the ENTIRE rpm range, particularly near redline, but was told by Nels at 2WheelDynoWorks when I decatted my Super Tenere in 2015 that it was ok to ride the bike from  Vancouver, BC to Seattle to get the flash so long as hard use, higher rpms & significantly increases in elevation were avoided...Nate also echos the same instruction for my 2021 T7 as I will be riding down for my flash in a week after replacing the oem air box lid with a MWR Filtercage & Outercover & installing a Black Widow decat header & MIVV Dakar high mount exhaust.  I have been riding the bike for a few weeks with that set-up plus the O2 sensor already unplugged keeping rpms <7k rpm & seldom >6k rpm & the bike seems to run well with no significant increase in popping under deceleration or other signs of overly lean fueling.

[Toymaster]

Hmmm,  I would question any mapping that required disconnecting the feedback sensor.  This means there is no feedback into the program, there is just an assumption their factors are correct. 

 

What is an oxygen sensor (O2 sensor) - NTK vehicle electronics

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NGK SPARK PLUG on the o2 sensor's function, bad oxygen sensor symptoms and how to replace a sensor correctly. Check it out.

 

[prowlnS10]

1 hour ago, Toymaster said:

Hmmm,  I would question any mapping that required disconnecting the feedback sensor.  This means there is no feedback into the program, there is just an assumption their factors are correct. 

 

What is an oxygen sensor (O2 sensor) - NTK vehicle electronics

---

NGK SPARK PLUG on the o2 sensor's function, bad oxygen sensor symptoms and how to replace a sensor correctly. Check it out.

 

Nate Phipps at 2WheelDynoWorks would be able to provide the best answer for any specific motor, but I believe that the oem narrow band O2 sensor is primarily used for the epa 'closed loop operation' which only controls very small portions of most motorcycle's engine throttle, rpm & load range & are set to maintain a fixed, lean (generally 14.7:1) air fuel mixture for emissions purposes, which is not optimal for performance, throttle response or engine longevity.  Once your bike’s throttle opening percentage, engine load and/or engine RPM exceeds the 'closed loop operation' parameters (this is usually above only 10-15% throttle and roughly 1/3 of the way through an engine’s RPM range) the O2 sensor input is ignored in what is known as 'open loop operation'.  Good custom ecu mapping done on a dyno to match intake, engine & exhaust modifications will provide proper mapping over the entire operating range & still incorporate other sensors such as intake air temperature sensors and barometric pressure sensors that play a significant role in both 'closed loop' & 'open loop' engine operation fuel mapping algorithms.

 

Here is a good FAQ from 2WheelDynoWorks that addresses your O2 sensor concerns & Ethos's original question.

Edited April 29 by prowlnS10

[Toymaster]

Yeah I remember now my thought process....  I went with a piggyback controller as I didn't have to have bike downtime and could revert back to stock at any time in my garage, plus I found it for ~$250.   The only down side to the extra ECU is mounting it, all they give you is velcro and foam. 

 

 

 Both sides say their way is the 'best' way.  Below is copied from Rapidbike Evo advert.   

 

"Modulating the stock O2 sensor (lambda) signal is a technology far more advanced than the so called “O2 sensor eliminator” (or any other similar device used by the competitors) since they send a static/constant signal which is in conflict with the typical behavior of the lambda sensors, therefore causing the main ECU to perceive such a constant signal as a mistake to be corrected. Thanks to RapidBike exclusive technology for the modulation of the stock lambda signal the main ECU considers this behavior as standard, therefore it will not try to re-set the stock engine parameters. The range of injection’s adjustments is from -100% to +150% of the stock injection time. Can also be adjusted manually during dyno tuning."

 

I have a heavy background in automation so very familiar with reality and not easily tricked by advertisements.   I'm not a fan of stripping out intelligence nor of over complicating a system.   Without actually looking at their programs my guess is, an educated guess that is, that both ways work and I'd run either.   I did spend a minute or two debating which way to go, but the logistics specific to me was the deciding factor. 

[CoreCass]

decat and a bigger snorkel. [i want a snorkel for water crossings.]

 

i did notice it. 

i also did a ecu flash as i dont beleave in piggy back systems.  but you do you.

if you decide to do ecu flash. dont go to every john doe. pick one with racing background and a lot of reviews.

 

its a difference by day and night. also need to add. thy put it on a dyno. not just send in ecu. thy actually fitted it to the bike instead of copy past