Both. Forcing readiness isn't a problem, I can make that happen quite easily with a separate flash but that's not something a company like MHD can implement into their flasher due to legal issues so we are looking for ways to keep the car happy wothout cats and not cayse any legal problems for MHD.
Readiness - Catalyst
- Thread starter carabuser
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One more data point: on my IKM0S car, just changing C_TEMP_CAT_MIN_LAMB_PLS_ACT to 1774 fixed the oscillation. Address for IKM0S which I changed is 0x4199C
Before log: https://www.spoolstreet.com/graphs/...ttachment_id=65054&series=17,18&zoom=-10,1020
After log: https://www.spoolstreet.com/graphs/...?attachment_id=65052&series=17,18&zoom=-7,738
Before log: https://www.spoolstreet.com/graphs/...ttachment_id=65054&series=17,18&zoom=-10,1020
After log: https://www.spoolstreet.com/graphs/...?attachment_id=65052&series=17,18&zoom=-7,738
Was wondering if "forced stimulation" had something to do with it, at least on some cars. Mentioned it way earlier in this thread. Hadn't really messed with it much because other potential solutions were given that fixed the oscillations for me, at least for now. @carabuser is "forced stimulation" something that can be disabled without being detrimental to other functions of the DME? I can't remember but I think I read in the docs that it's used to calibrate the lambda sensors.
The oscillations are always a result of forced stimulation. It's either done by adding an offset to the fuel target or by adding an offset to the trim controller.
I'll check to see if lambda calibration is affected.
Looks like forced stimulation is also possibly used to diagnose issues with lambda sensors. So, if forced stimulation is turned off completely, we may not get codes for bad sensors or bad heater element. Just waiting on confirmation that this is true.
Example from the literature:
"Furthermore, the forced lambda stimulation is used by diagnosis functions for the up stream
lambda sensor and by the catalyst efficiency diagnosis."
There are tables that seem to be related to non-emissions functions. If people have disabled forced stimulation completely and are running fine, maybe it doesn't actually matter much.
Example from the literature:
"Furthermore, the forced lambda stimulation is used by diagnosis functions for the up stream
lambda sensor and by the catalyst efficiency diagnosis."
There are tables that seem to be related to non-emissions functions. If people have disabled forced stimulation completely and are running fine, maybe it doesn't actually matter much.
Looks like LC_DIAG_DYN_LSL_UP_CAT_SYN can be used to separate sensor dynamic diagnosis from catalyst diagnosis. Default it's set to 1 (synchronized).
EDIT: This value actually seems to be disabled, 0, in I8A0S. May be why some were still getting oscillations even after disabling cat efficiency.
EDIT: This value actually seems to be disabled, 0, in I8A0S. May be why some were still getting oscillations even after disabling cat efficiency.
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Lol, that thought crossed my mind this morning, that would disabling forced stimulation prohibit detecting problems with the O2 sensors?
For IJE0S try this table:
Conversion factor for PSI: (X*0.08291752)/68.9475729
This should just disable cat diagnostic completely so if lambda oscillation still occurs it might be related to O2 sensor diagnostic which I can also dig out the tables for.
I had a quick look through the documents and some of these params will also halt certain O2 diagnostics.
The C_AMP_MIN_CAT param is just purely used to prevent the catalyst lambda oscillation so that should leave everything else untouched.
Car details: IJE0S, 2008 6MT, hybrid turbos, N20 TMAP DIY custom flash, flex fuel, DPs, IC, Stage 2 LPFP. I have it running well at WOT and is smooth to drive in nearly every condition - minus the highway cruise in my 2nd paragraph below.
OK, I set C_AMP_MIN_CAT to 78 on my IJE0S car. Can you tell me what conditions I should see impact? I was expecting at idle the AFR would be more stable - and not see the rich (down to 13.2) / lean (up to 15.2) cycles that the car endlessly goes through. I don't have a hunting idle - you would never know if not logging. I didn't log it, but can. The interesting thing is that this behavior doesnt start until idling for maybe 1 min or so. Before that it bounces between 14.4 and 14.9, which is expected.
What I was REALLY hoping this would fix is the random oscillations I get at 3K RPM in 6th gear (82mph or so) on the highway after driving at that speed for maybe 10min. It happens at very light throttle and is most noticeable when going down a slight incline. Resetting adaptions keeps it at bay for a while, but then it returns. It has to be some DME routine and I thought it might be this one. To be clear, I haven't done a drive cycle like this since flashing a few minutes ago. And not sure it would be definitively proven to be linked to C_AMP_MIN_CAT until I drive for a few 1000 miles.
The lambda oscillations will occur all the time when engine load is low. The surging at 82mph is a textbook example.
C_AMP_MIN_CAT doesn't seem to work for many, maybe the cause for most is the O2 sensor diagnostic.
Try adjusting this value to1774:
Conversion: (X*0.0625)-273.15
I will test this one out. Here is an older log where this became severe, no idea why. Resetting lambda, throttle and load control adaptions made it disappear. Please note that the throttle position relative to the accelerator input as well as the AFR surges. Backing off 200 rpm would make things go straight back to smooth. Downshifting into 5th and going 82mph would instantly make it smooth again. The only other theory I had on this one, is notice the WDGC after PID was at the floor (12.7%) before the oscillation started. Load act was over load req but some value - but not much. In my flash yesterday I dropped it to 10% - and did a long downhill run at 82mph. I noticed WGDC after PID was showing 10.6%, so maybe the wastegates on my hybrids are tighter than OEM?
This is the downhill cruise log from today after I lowered WDGC floor to 10%. Notice that there are points where WGDC after PID gets down to 10.7% and no oscillations or AFR bouncing.
Here is an idle log from today. It is kind of long, but notice that especially bank 1 drops into the high 13s fairly often, then swings back the other way. My oxygen sensor readiness is showing 'INCOMPLETE' so not sure if that is related or not. The other things that gets my attention is that for the first part of the log, the AFR is far more stable, then goes into bigger swings the longer you sit there.
Last point, I am certain the C_AMP_MIN_CAT is the right address for IJE0S. My shadow cat efficiency codes disappeared after raising it to 78, and that was consistent with the I8A0S behavior.
**Edit, I must be a moron, but don't see the embed datazap option in the post editor. Feel free to educate me.
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Update. I tested C_TEMP_MIN_CAT_LAMB_PLS_ACT on IJE0S by setting to 1774. This increased the stability of my AFR at cruise GREATLY. See attached log from cruising around 72mph on the highway.
One thing I noticed was that my Oxygen Sensor readiness was INCOMPLETE for some time. Not sure if it is related to the flex fuel flash or why exactly it never achieved readiness after probably 12 drive cycles. The catalyst one is also INCOMPLETE for obvious reasons. Wondering if the DME runs the stimulation until one or both of these are set to COMPLETE.
Either way, this was a home run for me.
If you take requests to find/test new tables, would love to get the cold start HPFP tables. About to drop in a Helix and would prefer not to just completely bypass them by lowering the coolant temp to -40*C or whatever so it is always hitting the warm tables.
One thing I noticed was that my Oxygen Sensor readiness was INCOMPLETE for some time. Not sure if it is related to the flex fuel flash or why exactly it never achieved readiness after probably 12 drive cycles. The catalyst one is also INCOMPLETE for obvious reasons. Wondering if the DME runs the stimulation until one or both of these are set to COMPLETE.
Either way, this was a home run for me.
If you take requests to find/test new tables, would love to get the cold start HPFP tables. About to drop in a Helix and would prefer not to just completely bypass them by lowering the coolant temp to -40*C or whatever so it is always hitting the warm tables.
I don't think O2 sensor readiness can complete when catless. I can't remember exactly the order but one of the monitors relies on the other to complete first. I think the O2 sensor monitor won't start if there's a catalyst error code active (even if it's masked by MHD). It'll vary between ROM versions but I'm pretty sure MSD81 ROMs are like that.
I should be able to find that table if you tell me what coolant temp setpoint you change to bypass it.
I should be able to find that table if you tell me what coolant temp setpoint you change to bypass it.
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