View Full Version : what exactly is the ECM?

08-11-2008, 02:25 AM
can someone please put this to rest for me... whats the ECM do? and what would happen if a stock xb9s with a stock ECM got a buell race pipe put on it? i know it would start & run. i have heard that all the ecm does is make the speedo correct with the new muffler, but it has to be more than that right?

08-11-2008, 03:16 AM
ECM=Engine Control Module.

Its job is to monitor and control the engine using a variety of sensors (Oxygen sensor, intake air temp, camshaft position, throttle position, etc) and it has built in data for the fuel maps and spark timing.

It takes all that data and uses it to compute fuelling values and spark timing. It controls the fuel injectors and coils accordingly.

Has absolutely nothing to do with speedo.

As said in a few different forums, race pipe=more airflow through the engine. The more air you push through it the more fuel you need to add to maintain proper combustion. The ECM is able to compensate for that additional airflow (to a certain extent) the Race ECM changes the fuel/spark maps to account for the race pipe.

Hope that helps.

08-11-2008, 09:44 AM
gotta have a [up]vote for that...:p

08-11-2008, 12:47 PM
Thanks dude. I was bored last night, my kids were driving me nuts so I plunked them in front of a movie.

But hey, I'll take rep points at the expense of ridicule. :D

08-12-2008, 03:29 AM
Question about the ECM- what have they done to improve the ecm’s in the bikes since 03, and how is it really an improvement? My 03 seems smoother and more powerful than the newer ones with MUCH better gas mileage, seems like the 'improvements' have done nothing but harm to the bikes and make them more complicated. Just my opinion but what do you guys think?

08-12-2008, 12:07 PM
several things that would involve environmental laws, smoothing powerline, etc etc.

i forgot how mine was standard to have a decent comparison in how well it rides.

08-12-2008, 01:44 PM
it seems like there has been no improvement, I went and test drove an '08 a cupple months back at it was horrible, the fueling seemed like it was always searching and was not consistant, mine in comparison is very good. you are right though, it probably is a lot better for the enviorment. I just thought that with so many revisions it would be better not worse.

08-12-2008, 02:13 PM
you can't compare an '08 with an '03 and say the ecm blows...the engine is totally different.

08-22-2008, 03:01 PM
okay, well no one really answered my question... what would happen if you put a race muffler on a bike with a stock ecm & rode it?

08-22-2008, 03:03 PM
Your bike would run lean

08-22-2008, 10:32 PM
okay, well no one really answered my question... what would happen if you put a race muffler on a bike with a stock ecm & rode it?
that Q had a A several times on this forum.
this is one of them: ecm required with slip-on? (http://www.buellxb.com/Buell-XB-Forum/Buell-Firebolt-XB12-XB9/ecm-required-with-a-slip-on)

09-02-2008, 04:15 AM
okay, okay. its just a lot easier to ask instead of surfing thru 100's of pages hoping its been explained somewhere else. i guess i would like to hear from someone who has tried it, instaead of what the money-hungry HD dealers tell me.
if thats the case (^^^), my bike has been running lean for quite awhile now & no problems. i guess i dont understand how air coming out of the engine (exhaust) has anything to do with the intake of gas/air mixture going in? the race pipe has higher flow-thru, so if the flow was good enough with a stock, it should be a breeze thru for the race muffler.
im not too worried about trying things on my old 03 lightning, its been thru a lot already.. first bike i EVER rode, so you can imagine! but i want to keep my new buell legit & if a new mufflers gonna cause damage or something without a crap-load of mods, forget it.