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kicking out the cat

3K views 18 replies 9 participants last post by  simcity 
#1 ·
I have a catless link pipe in a box. Intended use F4 1000R 2007

I'm wondering what would happen if I took off the cat link pipe and fitted it keeping with the stock ecu.

What changes does the ECU sense when the cat goes missing and why is it customary to fit a microtec thingy at that stage...?

Would the bike start running like a bag of bent nails..if so I don't understand why as the ecu modifies fuel injected to manifold pressure ??

learning curve steepening :)

joe
 
#3 · (Edited)
Thanks Noel..

I'm pretty well at a zero knowledge level on the workings of the ECU..but I used to be able to program my Commodore 64 back in the day : )

You're spot on that there is no manifold pressure sensor..I was thinking more of throttle position sensor which by default gives the ecu a manifold pressure reading ? kindof ? I was working on a Moto Guzzi yesterday and thought as I worked ..there really is no MPS on my F4 lol

( paragraph deleted )

I have more questions than answers here Noel but what changes..Why do peeps go and fit a Microtec , which I know is $£$£$ there must be some parameter the oe ecu can't process when the cat is out..

thanks for your advices : ))

joe
 
#4 · (Edited)
I'm just looking at the 02 sensor on the stock link pipe. It is fitted up stream of the catalytic converter core. That means it is sampling exhaust gases before they pass into the catalytic converter itself.

To my simple mind that suggests that the ecu would not know anything at all if the cat wasn't there so long as I leave the 02 sensor in the same position in the pipe.

I still can't understand why I would need a Microtec if I take the cat out . The stock ecu wouldn't know the cat has gone ..I'm back to the only change is back pressure//perhaps ??

joe
 
#5 ·
Joe,
I don't know you remember my posted, I took out the cat from oem midpipe and using oem ecu also using race ecu still poping and back fire, as far as I know either you can add PC3usb to get dyno tunning or microtec to get all that poping and back fire to go away.
 
#6 ·
Thank you Phil.. appreciate the benefit of your experience.

The question Im particularly asking is, considering that the Lamda sensor is upstream of the Cat core...if I leave it in place in a catless link pipe there should be no difference in the 02 ...So why would I need a Microtec.
?


joe
 
#7 ·
I had an o2 sensor bung welded into my mid-pipe and ran the stock ECU with no cat and Arrow cans with no problems. With the dB killers installed. dB killers out made the fueling a touch lean on decel and I got some afterfire but otherwise it ran fine. I now have the MV Corse cans and "Kit" ECU and 02 sensor dead. Bike runs fantastic and guess what? I still get some afterfire on decel but I like it.

So this is what you do....get a bung welded into your mid-pipe and put it on. leave everything else stock and you will be fine.

People install the Microtech because you can tune the engine for much better performance in all regards. Do you have to have it? No, but if you can afford it then it is a terrific upgrade.
 
#11 ·
The bike will run very well without the cat....and you lose some weight as well.
 
#12 ·
missing link




Yes Ed I believe you are correct to the tune of 100%

I've been racking my brain cell..( poor little blighter ! ) and it's dawning on me that if there is more air pulled into the cylinder ( due to reduced back pressure ) then this will be sensed by the Oxggen sensor which of course I will have fitted to the link pipe..

joe
 
#13 ·
For info. I have a 1000S with a decat mid pipe and standard cans. Lower temp = yes (although mine never really suffered from that, especially here in the UK!!). Lower weight = yes. Also has a slightly deeper exhaust sound. Mine ran OK but replaced the OEM chip with a race chip and it feels better under 4,000rpm than it did. I don't believe there is any performance gain, but I for one don't need any more than it has already. I did intend to fit race cans of some sort to accompany the decat pipe, but funds dried up and I think if you go down that route you may as well think about a PC3 or new ecu and a dyno session -even more money unfortunately.
 
#16 ·
runs lean

I put arrow thunder on my brutale with decat. MV said that if I had put on the MV pipes they would just change the ECU to race version but that the change was too large for the parameters of the std ecu removing both std pipes and cat. Best option PC5 or microtec and get it tuned. Just removing cat is probably ok(?) but not changing both.
I decided to get it dyno tested to be safe. It is running lean on lower revs but runs rich as the revs build. Rides great with a superb crackle on decel but would prefer to get a microtec just to be safe....
Good excuse to keep the revs up though in meantime.
 
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