MOT today... emissions thoughts

M

Mr Whippy

Veteran
 Harrogate
... and it passed, yay.

With secondary de-cats it still managed to pass the emissions test. Last year it just failed but I think running on 98RON petrol and recently having fitted new ignition coils and having a nice new oil top up it seemed to do the trick!
My car is on 103k miles now and passed ok but since it failed last year I still wouldn't want to say for sure if these cars NEED the secondary cats to pass an MOT emissions test. Has anyone else gone with secondary de-cats and had good or bad luck at the MOT test?


I had a few advisories too, rear diff seals starting to seep and rear brake pipes and front to rear brake pipe starting to corrode a bit... I guess that is ok at 8yrs/100k miles now!


Cheers

Dave
 
Just had the rear brake pipes done on mine couple of weeks back for the MOT - front to back was £180 also the hoses x4 were 130 from bmw direct as the indie couldnt source a replacement, no doubt the rear diff seals i will have to watch for next year :-) What power increase did you feel / see when removing the secondary cats?
 
Not sure on the power increase yet.

I need to go test it one day.

I'm not sure if the ECU does any adaptation after removal/refitting, but obviously as prevailing conditions change the results of any tests will change... even controlled dyno conditions may change (ie, tyre temps might impact things enough to blur any losses/gains and they are not considered)

So it'll be a tough one to check for sure.

Currently plan is to run the car to the workshop, do a few acceleration runs in various gears and log the accelerative g's.

Then remove de-cats, fit cats (and do a weight check too), and then immediately go do the same acceleration runs again.

Then leave them on for a few hundred miles, then invert the test again.


That way hopefully if I see a same percentage change one way then the other then we can say the impact is immediate. Otherwise I'll have to consider some other measurement process.


I'll try sort some decent quality high bit-rate fixed gain audio recording too, so I can do some full-throttle passes and on-car sampling so you can get a real idea of before/after difference in sound and volume... but I might have to do that another time.


Next job will then be combining the de-cats with some remapping to see what happens. I'm hoping I can get 15bhp from the combined package, maybe 20bhp with an optimised back box, but until I get it all rolling I won't know for sure.

Cheers

Dave
 
Sounds a lot of effort/cost for 20bhp.

Do the decats change the note of the system at all? I essentially "decat'd" my v6 mundano once. It had a janspeed system from the cat back but the cat started rattling badly and then I started loosing power at higher revs so me and a mate took a crowbar to the cat. It solved the two problems and made the note a bit raspier
 
Well, it's not just for 20bhp, but I'll be remapping to enhance other aspects of the car where possible. It might be more than that, perhaps less, but I want to work out how much by remapping myself. I just don't trust the 'generic' operators offering 20bhp+ from just a remap when Dinan and ESS offer just 5bhp... who knows but if I DIY it with good exhaust mods then we know for sure rather than just speculating :D

I want to take a look at controlling an exhaust flap (the controls are in the MS45 ECU, just not activated like they were on 3 series). I also want to look into tweaking the throttle maps in sport mode to give a nicer linearity (keep the travel longer, but up the response), and also try adjust steering weight in sport mode if possible to make it heavier at higher speeds (less assistance)
I might simply have the 12v sport button activation operate a solenoid to send vacuum to the exhaust valve actuator so the car gets loud when in sport mode... not sure on that yet though.


Yes, the de-cat secondaries make a big difference to the sound. You get a proper bark and a bit more rasp at all times, and off the throttle at the right times you get a decent crack and pop overrun which has people turning around to see what is coming!


Dave
 
Looking like it might be BDM and TunerPro at this rate, and some solution to do the checksum... not sure what yet hehe.

Have you done much looking into the Electric Power Steering. I'm about to take another look through my resources but I'm getting to the point where I think the control maps for EPS must be inside the main ECU data with the engine, DSC/ABS/ESP elements too.

Dave
 
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