Stock ECU CO mod vs. aftermarket programmer

Elm wrote:

skierd wrote:
The bike makes slightly more power and has a somewhat smoother powerband with a programmer. The CO adjustment works just fine too though, just not as 'precise' as the programmer's adjustments. I'm happier without the programmer and my CO set at +12 (stock -2) with a full FMF exhaust and minor airbox mods since it no longer stumbles and studders at mid to low rpm with low to mid throttle input.


^What he said. Perfect all through the rev range with these mods and +12 increase.
The power is quite outstanding & I'm coming off a XT12 Super Tenere.

what exactly is "minor airbox mods"? I would like to save a couple hundred bucks and try this route. Just want to make sure I get the right air mods done. Got the full FMF exhaust system already.

Thanks!

paulie1960 wrote:

Probably the best mods on a budget are
1. unifilter flows better than K&N
2. open up air box two 3/4" holes and remove flapper
3. keep the exup and open up the stock exhaust  (the wrr with stock cam timing needs back pressure for low end power)
4. adjust your CO and  the TPS needs to be set at 18 - 98
then you dont need a controller

http://dualsportalchemy.com/2015/05/franks-2012-yamaha-wr250r-exhaust-modification/
Link shows where to cut pipe to cut out cat. I left my exup valve working. plus I drilled one 1" hole thought pipe.
Looks stock and not to loud.
TPS do search on wr250r TPS mod. CO mod only does idle.

sock monkey wrote:

So, I've read lots and lots of posts re. "will I blow up my motor if I uncork my WRR and don't buy a programmer?", and "what programmer should I buy?", etc.  My question to the group here is "why spend $$$ on a programmer if you can freely adjust the stock ECU?".

"Freely adjust the stock ECU" you say!?!?!  YES!!!!  Why doesn't anyone talk about this?  Is it a dirty "secret" and now that I've posted it here men in black suits and dark glasses will show up at my house and cart me and my WRR away.  This is so bizarre.....  

Anyway, for those who don't know, you can make your stock ECU richer/leaner via the built-in diagnostics.  The only catch is on the US bikes, you need to ground an unused wire found in the plug for the lean angle sensor.  Once you do this, you can enter the DIAG mode, then enter the CO mode, and richen/lean between -30/+30 (stock the bikes are set to -2 in the US....a bit of proof that these bikes are "lean" from the dealer eh?    ).  The step by step details on how to do this are found in various places on the web, so I won't repost them here unless folks can't find 'em.

So....before the "bad men" come get me, why aren't more peeps using this freebie mod and instead mucking with setting up a $$$$ aftermarket programmer???  

-SM

I apologise for the thread bump. I can indeed confirm that the co value only impacts idle and low rpm. Tested by measuring the exhaust O2 sensor.

Arkmage wrote:

Keep in mind also that the euro bikes have an O2 sensor and run closed loop.  A lot of the guys I've seen running lots of mods without a programmer are running a euro model.

Since ours are open loop the CO mode may not have the same level of impact on the over all tuning of the bike.

Do we have any evidence of closed loop operation on aus and euro bikes?

combo wrote:

0007onWR wrote:

There is no possibility that you are taking advantage of the exhaust system and air box mod if you don't have a programmer

How would you know? did I just imagine the 20% increase in performance on my bike after some mods plus my 02 sensor in a FMF pipe?

When we used a voltage meter to test the 02 sensor it was busy throughout the revs of the bike

Hi Combo, please may you explain what changes you saw in the voltages in the o2 sensor when you measured?

From my testing the O2 sensor responds to the exhaust oxygen content but the ECU does not use this at all in any way. O2 sensors should operate in a feedback cycle with the ECU, but sadly my o2 sensor was static.



"When warm. You can test the O2 sensor on a vehicle by first identifying the signal wire on the sensor. Secondly, by using a voltmeter with the scale set to 1 volt, the voltage will fluctuate between 200 and 800 millivolts or .2 to .8 volts on your meter. If the sensor’s reading is stalled in position, or switches abnormally high or low, your sensor has failed"

My testing on my WR250R:
Always when cruising in what should be closed loop conditions 0.93-0.95v (max rich measurement possible).
Voltage went down when decelerating. To around 0.3-0.4v.

This would indicate running too rich all the time.