Readiness - Catalyst

[email protected]

Major
Platinum Vendor
Nov 7, 2016
1,531
1,972
0
Philly
This toggle is not magic, you will not pass a true emissions test with catless downpipes with or without it. That person was a fluke and somehow got lucky (if true). As I stated above, this function is actually intended to improve catalyst efficiency (when used with OEM downpipe)
 

carabuser

Lieutenant
Oct 2, 2019
624
1
491
0
UK
Ride
Z4 35i & 335i
This toggle is not magic, you will not pass a true emissions test with catless downpipes with or without it. That person was a fluke and somehow got lucky (if true). As I stated above, this function is actually intended to improve catalyst efficiency (when used with OEM downpipe)
UK and some EU emissions tests are based on tailpipe emissions and don't consider monitors at all. My own cars both pass the local testing requirements here just by using the secondary cats alone.

The reason I noticed the oscillating afr was because of this testing. I was trying to tweak the tune to run leaner and give me a better chance of passing the CO2 limits and I noticed the target lambda from the DME was all over. The idea of the oscillation is that it should average out between both banks but I believe the overall effect is an increase in both unburned fuel and an increase in NOx so fixing this should help genuinely reduce emissions.
 

335iN54

Lurker
Sep 4, 2021
21
3
0
UK and some EU emissions tests are based on tailpipe emissions and don't consider monitors at all. My own cars both pass the local testing requirements here just by using the secondary cats alone.

The reason I noticed the oscillating afr was because of this testing. I was trying to tweak the tune to run leaner and give me a better chance of passing the CO2 limits and I noticed the target lambda from the DME was all over. The idea of the oscillation is that it should average out between both banks but I believe the overall effect is an increase in both unburned fuel and an increase in NOx so fixing this should help genuinely reduce emissions.
It definitely runs on the richer side on idle oscillates between 13.9 to 15.1 confirmed by quite a few users...
 

JohnDaviz

Lieutenant
Jan 6, 2019
708
419
0
Ride
335i E92 DCT
I am really curious. I have some oscillation going on on idle and light load.
It has been forever now. I am on INA0S.

If there is anything i can test to get rid of this i would love to test (once my engine is back in the car).

Bildschirmfoto 2022-01-21 um 16.30.11.png
 

carabuser

Lieutenant
Oct 2, 2019
624
1
491
0
UK
Ride
Z4 35i & 335i
I am really curious. I have some oscillation going on on idle and light load.
It has been forever now. I am on INA0S.

If there is anything i can test to get rid of this i would love to test (once my engine is back in the car).

View attachment 64163
When your car is back on the road just send the bin over and I'll apply the same changes I made to my INA0S cars to stop it. I might give you 3 different bin files each with a different fix to see which one fixes it exactly in your circumstance.

Before this becomes a fix that Jake can add into MHD it needs plenty of people testing it.
 
  • Like
Reactions: JohnDaviz

KClemente

Corporal
Nov 26, 2019
231
108
0
Ride
E90 335i
Raising the min cat temperature requirement (c_temp_cat_min_lam_adj_act) helped out my fluctuations on my MSD80 whenever I target 1 lambda at idle.

For anyone that runs higher than 1 lambda at idle, raising the cat temperature req is not necessary as you'll be operating (idling) above the max lambda requirement anyway.

I did 3 tests

Test 1:
Target AFR: 16
Fluctuation of 15.9-16
1% dips to 15.8

Test 2: By far largest delta in fuel
Target AFR: 14.671
Fluctuation of 14.2-14.8
1% dips to 13.8

Test 3: c_temp_cat_min_lam_adj_act adjusted and nothing else
Target AFR: 14.671
Fluctuation of 14.4-14.7
1% peaks of 14.8

My "smoothest" idle was achieved by targeting an AFR of 16.0
 

studio54

Private
Dec 20, 2021
47
16
0
@KClemente Nice, I didn't think about raising my AFR so much because my first intent was to smoothen my AFR for my failed emission test (high CO) and at the tailpipe test a lambda higher than 1.03 (AFR 15.14) is a fail.
I also thought that this 13.8-15 oscillation function took over AFR target values, so in my head we had to fix the idle/low load oscillation prior touching AFR tables, it seems it's not the case according to your tests.

Here my two logs for comparaison (stock AFR target 14.67) :

BEFORE
AFTER

Night and day, even if a bit of oscillation is inevitable I think.


Otherwide and if it could help other people, my tailpipe sniffer emissions passed successfully yesterday, I think it's a combinaison of three things :
- Oscillation fix (those pulsating dips in the 13.8 aren't good for CO emissions)
- low load AFR to 14.900 (equals to a lambda value between 1.01 & 1.02, I wanted to be borderline of the limit of 1.03 to reduce CO)
- E30 blend (to reduce CO too)
 
  • Like
Reactions: KClemente

TSilver335i

Corporal
Nov 18, 2018
107
46
0
Australia
Ride
08 335i

corbanistan

Corporal
Jul 26, 2021
140
1
60
0
Florida, USA
Ride
E93 335i 6MT
This toggle is not magic, you will not pass a true emissions test with catless downpipes with or without it. That person was a fluke and somehow got lucky (if true). As I stated above, this function is actually intended to improve catalyst efficiency (when used with OEM downpipe)
If a toggle to stop idle oscillations might be added to MHD in the future, might I suggest that toggles for other catalyst routines (cat purge, cat monitoring, stimulation, etc) be available as options as well, or all-in-one? I'll always disable these things via tuning personally, but for those using OTS maps or those who hire a tuner.

On a different note, I have notice pretty bad idle fuel consumption. I live in a hot climate, and during Covid I had to sit in my dog's vet parking lot during her visit for an hour. I kept the car running with AC on. The fuel it consumed idling during that hour was higher than I've ever seen in any other car. And sure enough oscillations were happening that whole time. So I believe these routines are definitely having an effect.
 

corbanistan

Corporal
Jul 26, 2021
140
1
60
0
Florida, USA
Ride
E93 335i 6MT
Just wanted to add, last night I loaded on an updated tune with some of the changes mentioned in this thread. Leaned out AFR at idle. Idle is much smoother and quieter. Oscillations seem to be gone on my end too.
 
  • Like
Reactions: carabuser

335iN54

Lurker
Sep 4, 2021
21
3
0
Just wanted to add, last night I loaded on an updated tune with some of the changes mentioned in this thread. Leaned out AFR at idle. Idle is much smoother and quieter. Oscillations seem to be gone on my end too.
I have missed that smooth stable idle since I went catless.
It amazes me how majority of people do not notice the idle smoothness degradation on catless or maybe I pay too much attention to the details!

I have also noticed a bit more soot build up in the exhaust, dps and on O2s tips that might relate to that extra unburned fuel from the toggles...
 

corbanistan

Corporal
Jul 26, 2021
140
1
60
0
Florida, USA
Ride
E93 335i 6MT
I have missed that smooth stable idle since I went catless.
It amazes me how majority of people do not notice the idle smoothness degradation on catless or maybe I pay too much attention to the details!

I have also noticed a bit more soot build up in the exhaust, dps and on O2s tips that might relate to that extra unburned fuel from the toggles...
Yeah that's to be expected from being catless. Everything's perfect for me now after this. Only thing I get now is a single stumble at idle once in a while. Doesn't change anything really but it annoys me regardless! Will eventually replace O2s, sparks, and purge valve as scheduled maintenance soon anyway, we'll see if that fixes it.
 

335iN54

Lurker
Sep 4, 2021
21
3
0
Yeah that's to be expected from being catless. Everything's perfect for me now after this. Only thing I get now is a single stumble at idle once in a while. Doesn't change anything really but it annoys me regardless! Will eventually replace O2s, sparks, and purge valve as scheduled maintenance soon anyway, we'll see if that fixes it.
I did have few stumbles on cold start on ngk plugs, switched to bosch n55 plugs and its sorted...
 

corbanistan

Corporal
Jul 26, 2021
140
1
60
0
Florida, USA
Ride
E93 335i 6MT
I did have few stumbles on cold start on ngk plugs, switched to bosch n55 plugs and its sorted...
Hmm I like the NGKs but I think I might have them gapped too small. I've heard the recommended gaps for tuned are just a little bit conservative and can be a little larger. May try that first.
 

Dyyd

New Member
Aug 10, 2019
6
0
0
Ride
335ix
Not starting a new thread since this question is related to subject.
Does anyone have the info on what was the maximum load (in the load table) where cat readiness can still come on. I remember someone on some forum specifying this but did not find it anymore.

Also great info on the catless rpm fluctuation. I ordered area74 cat sims to see if that cures the issue without other changes. What I noticed when troubleshooted this earlier on my own that the fluctuation goes away at least for a while if every lambda adaptation is reset with inpa.
 

corbanistan

Corporal
Jul 26, 2021
140
1
60
0
Florida, USA
Ride
E93 335i 6MT
Not starting a new thread since this question is related to subject.
Does anyone have the info on what was the maximum load (in the load table) where cat readiness can still come on. I remember someone on some forum specifying this but did not find it anymore.

Also great info on the catless rpm fluctuation. I ordered area74 cat sims to see if that cures the issue without other changes. What I noticed when troubleshooted this earlier on my own that the fluctuation goes away at least for a while if every lambda adaptation is reset with inpa.
There's a few tables you could use but this sounds like what you're after:
IP_MAF_MAX_CAT
"max. MAF threshold for catalyst diagnosis activation"
 

335iN54

Lurker
Sep 4, 2021
21
3
0
This toggle is not magic, you will not pass a true emissions test with catless downpipes with or without it. That person was a fluke and somehow got lucky (if true). As I stated above, this function is actually intended to improve catalyst efficiency (when used with OEM downpipe)
Any chance of MHD implementing this change in the flasher?

I am happy to participate in any testing as I run OTS maps unlike most people here which run custom tunes.
 

carabuser

Lieutenant
Oct 2, 2019
624
1
491
0
UK
Ride
Z4 35i & 335i
Any chance of MHD implementing this change in the flasher?

I am happy to participate in any testing as I run OTS maps unlike most people here which run custom tunes.
Implement what? We're still trying to work out exactly what the magic bullet is for inhibiting this behaviour.

I've figured out a way to patch the diagnostics out completely for my own vehicles but it can't be done via MHD as it probably falls foul of emissions regs. So if people want a method MHD can implement then they need to get involved and test the tables mentioned in this thread.
 

Dyyd

New Member
Aug 10, 2019
6
0
0
Ride
335ix
There's a few tables you could use but this sounds like what you're after:
IP_MAF_MAX_CAT
"max. MAF threshold for catalyst diagnosis activation"
Hello
What would be the location where to find this in I8A0S and what is the default value? Anyone tested this?
 

Dyyd

New Member
Aug 10, 2019
6
0
0
Ride
335ix
Implement what? We're still trying to work out exactly what the magic bullet is for inhibiting this behaviour.

I've figured out a way to patch the diagnostics out completely for my own vehicles but it can't be done via MHD as it probably falls foul of emissions regs. So if people want a method MHD can implement then they need to get involved and test the tables mentioned in this thread.
Patch the diagnostics in such a way that they will not interfere with normal operation or in a way you would get the readiness bits set?