DYNOJET: Power Vision: Actual vs Commanded AFR after tune way rich
#1
06-07-2018, 08:32 PM
Power Vision: Actual vs Commanded AFR after tune way rich
'18 RGS, 120" M8, D&D 2:1 pipe, PV with widebands... I can provide all the build details if needed, but here's the gist:
I've tuned a few bikes with Power Vision over the last several years and have had very good success. This 120" M8 build has me puzzled. I can do several AT pro runs on the street using the widebands and it makes VE corrections. After several rounds the corrections are within a few %, so I flash in the results, but the actual AFR shown when using the datalog view is way richer than commanded. It also shows this in data logs.
For example, at light cruise 35 KPA, 2500 RPM, I am commanding 14.3 AFR, but showing as rich as 13.2. This will even continue at 40KPA and in higher RPMS. There are some ranges where it does behave as expected.
This is all at normal engine temps.
Any ideas?
Tempted to throw the narrow bands in and see what happens.
I've tuned a few bikes with Power Vision over the last several years and have had very good success. This 120" M8 build has me puzzled. I can do several AT pro runs on the street using the widebands and it makes VE corrections. After several rounds the corrections are within a few %, so I flash in the results, but the actual AFR shown when using the datalog view is way richer than commanded. It also shows this in data logs.
For example, at light cruise 35 KPA, 2500 RPM, I am commanding 14.3 AFR, but showing as rich as 13.2. This will even continue at 40KPA and in higher RPMS. There are some ranges where it does behave as expected.
This is all at normal engine temps.
Any ideas?
Tempted to throw the narrow bands in and see what happens.
Last edited by VDeuce; 06-07-2018 at 08:34 PM.
#2
06-08-2018, 07:13 AM
With the Auto Tune Pro, when you auto tune, the Power Vision changes the entire map's desired/target af ratio to 13.0:1. Then as you are auto tune, it is trying to reach that 13:1 target under all loads and rpm ranges. When you export learned and shut off auto tune, it puts the desired ratio back to your previous target afr. It has to then calculate what the VE "should" be to get it to the new target, say 14.3:1, based on what the actual VE that was needed to get to the 13:1 during auto tuning.
Now if you had the Target Tune module, when you set it to auto tune (with Target Tune), it does not change the target/desired afr, it stays at what you have in the map, thus your auto tuning will be much more accurate, as the Power Vision doesn't have to do a calculation to estimate the difference between 13:1 and whatever you actually want the air fuel ratio to be. Hope that makes sense.
If youre just having issues at cruise, I'd probably tune with the narrow bands next.
Now if you had the Target Tune module, when you set it to auto tune (with Target Tune), it does not change the target/desired afr, it stays at what you have in the map, thus your auto tuning will be much more accurate, as the Power Vision doesn't have to do a calculation to estimate the difference between 13:1 and whatever you actually want the air fuel ratio to be. Hope that makes sense.
If youre just having issues at cruise, I'd probably tune with the narrow bands next.
#3
06-08-2018, 10:43 AM
Stellar HDF Member
Possible during that light load (35kpa) the exhaust, due to reversion, o2 sensors are getting polluted with air, causing the system to richen the afr thinking it is lean.
I like to dictate where closed loop relies on the sensors and when they run off the VE alone. This way reversion is not in the mix which eliminates light load overly rich running.
Bob
I like to dictate where closed loop relies on the sensors and when they run off the VE alone. This way reversion is not in the mix which eliminates light load overly rich running.
Bob
#4
06-08-2018, 12:19 PM
#5
06-09-2018, 01:42 AM
Please excuse me, but I am trying to wrap my head around this.
I have no experience with the M8 tunes, but this seems like basic EFI tuning.
Your ECM is locked in open loop (because you are running the PV with AT Pro and wide bands) …
The tune you are running had had the VE tables tuned in in other areas as well as the problem areas using the PV w/AT Pro …
Now, still in open loop (because the wide bands are still hooked up) the AFR is way outside the target during light loads.
My first thought was either exhaust leak, and/or reversion.
But that would have been picked up during the AutoTune process, unless it developed after the tuning.
If you are sure you got some good clean data during the AutoTune runs, then I would be looking at when and where these deviations are occurring:
You said light loads, but was it light loads, or throttle position?
Was it constant, was it during acceleration, deceleration?
Is it constant in those cells, or just occasionally?
Was it on both cylinders, or just one?
If it were me, I would start by connecting the narrow bands and doing a few AT runs to see how far out the VE tables are per them.
And last, If you are going to limit the narrow band tuning you might consider either 60 and above, or 70 and above, but that is JMHO.
BTW, what exhaust are you running, and were the bungs for the wide bands in your headers, or did you have to have them inserted?
.
I have no experience with the M8 tunes, but this seems like basic EFI tuning.
Your ECM is locked in open loop (because you are running the PV with AT Pro and wide bands) …
The tune you are running had had the VE tables tuned in in other areas as well as the problem areas using the PV w/AT Pro …
Now, still in open loop (because the wide bands are still hooked up) the AFR is way outside the target during light loads.
My first thought was either exhaust leak, and/or reversion.
But that would have been picked up during the AutoTune process, unless it developed after the tuning.
If you are sure you got some good clean data during the AutoTune runs, then I would be looking at when and where these deviations are occurring:
You said light loads, but was it light loads, or throttle position?
Was it constant, was it during acceleration, deceleration?
Is it constant in those cells, or just occasionally?
Was it on both cylinders, or just one?
If it were me, I would start by connecting the narrow bands and doing a few AT runs to see how far out the VE tables are per them.
And last, If you are going to limit the narrow band tuning you might consider either 60 and above, or 70 and above, but that is JMHO.
BTW, what exhaust are you running, and were the bungs for the wide bands in your headers, or did you have to have them inserted?
.
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