M5 f10 decat

[drifter17a]

All,

does removing M5 f10 cat cause any issues apart from engine light?

Friend of mine has done it and no engine light but lots of error re fuel trim in info memory .

some posts suggests it makes the car run very lean and bust engine. i doubt if it does as engine can calculate air using afm and feedback from o2 to adjust map

in wide open throttle they use open mode so o2 reading is not used and only in cruising / low range /close loop o2 reading is used

[Ickdeep]

I'm not sure about the exact process but I know its not recommend to run catless downpipes on a stock tune. Your friend should look into getting a stage 2 tune for this car so that the computer is setup to run with that mod.

[Fast.F10]

Originally Posted by Ickdeep

I'm not sure about the exact process but I know its not recommend to run catless downpipes on a stock tune. Your friend should look into getting a stage 2 tune for this car so that the computer is setup to run with that mod.

A tune for certain. Isnt an SSP or similar "suggested" for any/all stage 2 tunes though?

[ajm55]

I’ve run catless dps on the stock tune on and off for the better part of 2 years without any issues. AFRs are dialed in and curiously no CEL

[M5_Raz]

Shouldn't have any problem at all. I am also planning on doing the same.

You can also buy a BM3 tune and modify your stock tune to remove the cat check. Then flash the modified stock tune back and you'll be stock with no CEL light.

[rockyfeller]

For anyone that thinks a stock tune can't be used with catless DP, any reason why?

Obviously you're not going to net gains that way but some of us just want the catless for the sound. Is there any harm done or performance loss from stock tune with catless DP?

[ajm55]

Originally Posted by rockyfeller

For anyone that thinks a stock tune can't be used with catless DP, any reason why?

Obviously you're not going to net gains that way but some of us just want the catless for the sound. Is there any harm done or performance loss from stock tune with catless DP?

Definitely some power gain although not optimized without a complimentary tune. Much better sound. Less turbo lag. I'm not aware of any downside and would also be keen to hear whether anyone out there has experienced any adverse effects

[rockyfeller]

The only thing stopping me from a tune is warranty concerns. I extended mine till 2023. If it weren't for that I'd do it in a heartbeat.

[drifter17a]

same here which is why I don't remap