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ECU tune required for catless?

15K views 21 replies 8 participants last post by  BaldyDave 
#1 ·
Hey guys -

I couldn't find a thread on this...I have a catless exhaust that I just put on my bike this past week...but I am already happy with the performance of the bike so wasn't considering any sort of retune...but do I risk causing damage to the engine (running too lean, etc)? If there is risk of damage...is this something I need to do right away?

Thx!
 
#7 ·
This is a topic hotly disputed on this forum though.....
........and here it comes.......

Whilst I agree a motor with catless headers will run OK with a BoosterPlug fitted..........from 1st hand experience I can confidently say it'll run even better (much better in fact) with a remap.

Yer pays yer money and takes yer chances!!
 
#10 ·
To my knowledge there has only been one person to test the AFR of their bike on here and he had an aftermarket filter, catless, no flapper and aftermarket exhaust all running with the stock map. the ECU adjusted everything perfectly to maintain the correct AFR.
 
#11 ·
I wouldn't say "perfectly" but well enough to keep us out of trouble. It's still emissions oriented mapping. That's the ECUs' priority and it's become even worse, stricter, with the 2017 and up bikes' BMS-M ECU with integrated CanBus.

This is where the aftermarket comes in. They go in and modify the ECUs' programming for performance. The ECU our 2014-16 R9Ts use is Bosches' BMS-K. The S1000RR until recently used it too.
 
#13 ·
I hope to get my R9T soon and test it on my dyno. What I can say is that the original ECU on the latest BMW must not be confused with the ones from other bikes. Whereas on the most of them you have several injection tables, when it comes to the latest BMW, as for the cars, you find some o2 sensor target maps and torque request maps for the throttle. This means that the AFR will remain similar even changing the exhaust, as the injection will be adjusted to reach the same target.
Now, this target is not set to be "optimal". It is set to make the bike to pass the Euro3 and (from 2017) the Euro4 regulations... in other words, it's lean. Will this break the engine? No. But it will affect the throttle response and low-revs smoothness. I am not saying that the bike runs poorly, just saying that it could run better.
The actual AFR target for the closed loop (up to 5/6000 rpm) is 1, which means 14.7. Working on it you can improve the response of the bike, lower the temperatures and get a few HP, especially if paired with an exhaust and intake.
How to do so?
Well, there are many solutions. I personally work with Rapid Bike, they are injection units that adjust the AFR by using the original o2 sensor. This means that you do not need to get it mapped on a dyno, unless you are really looking for up to the last hp and you trust your tuner's experience and tools. The down side of these units is that you need to fit them and on such a bike it is not easy to hide it completely. I will let you know how I go with mine.
Another solution - probably the most popular - is to reflash the ECU. Nice clean job, but you cannot "erase" it for warranty purposes and the results will depend completely on the tuner's experience and tools.
I would personally avoid the booster plug. It makes the bike to run in a non-coherent condition (as if it was colder) improving a little area and damaging the rest. Since the "issue" is limited to the closed loop range, a cheap o2 modulator such as the Rapid Bike Easy is a way better option. Same concept (showing a different value to the ECU), but limited to the most problematic area, without interfering with important information such as the temperature of the air.
Finally, I would avoid the old generation of fuel units as they are not effective in the closed loop. To install them you need to blank the o2 sensor, in other words you blind the ECU of her most important fueling tool.
 
#15 ·
Actually 14.6 is quite lean. But everything needs to be contextualized. 14.6 when cruising would be fine, even rich if you are going down a hill. This is a general opinion of course, then every bike may be different.
If it shows 14.6 when accelerating, well, this is lean. Especially at high revs, even more with two big cylinders as in this case.
Euro4 regulations are a bugger. Eternal engines such as the Ducati twin-valves, BMW Boxer, Aprilia V2 or KTM LC8 had to be deeply revisited in order to match them, and in the most of the cases they still lost their character that made them legendary.
With this I am not saying that the bike will break down. When adapting these engines, the quality of the pistons, rods, valves, springs etc.. was improved in order to deal with the higher temperatures and stress. At the same time, with a slightly richer fueling the bike will definitely improve, at least in the throttle response and smoothness.
 
#18 ·
I am currently running without the O2 sensors and the ECU mapping is correcting the fueling just fine. Lets just keep this topic civil without throwing daggers. If you really want to know your current AFR then I would suggest that you invest in a AFR Guage.

SAFR - Standalone Air Fuel Ratio Diagnostic Tool

http://www.ninetowners.com/forum/engine-technical-discussion/128889-afr-readings-racer.html

O2 sensors removed.

75 mph: 14.2
2nd gear wot: 12.3
3rd gear wot: 12.3

O2 sensors installed.

75 mph: 14.6
2nd gear wot: 12.2
3rd gear wot: 12.2
 
#20 ·
I am currently running without the O2 sensors and the ECU mapping is correcting the fueling just fine.
The ECU isn't really "correcting" for anything, with the O2 sensors disconnected you've lost it's mixture adaptability. What you've done is defaulted the ECU to a base fuel table it reverts to if it detects O2 sensor failure.
 
#22 ·
Closing this thread as this will turn into another Booster Plug Vs stock and remap options. Frankly this has been discussed in depth on other threads so there is really no value to be gained from going through it all again.

All the options have been highlighted here, stay stock, add a booster plug or get your bike remapped. Nothing more to be said and the forum can do without another bun fight on the merits/drawbacks of each option.

Thanks. :)
 
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