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Carsinc
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« on: June 10, 2013, 09:38:28 PM »
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Well I've been working on Vw and audi for around 12 years and have learned something new that I wish to talk about.
On me7.5 cars atleast the rear is used at least partly for long term fuel adaptation. I'm just now learning this
and I've been to atleast 2 vw advanced engine managment classes and one for fuel adaptation alone. I'm wording what
you folks know about this.
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ddillenger
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« Reply #1 on: June 10, 2013, 09:48:38 PM »
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I may be wrong, but I don't believe the rear o2 is used for lambda correction on the 1.8's. I know they are taken into consideration for the 2.7t, but I've never seen it in the 1.8s.
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Carsinc
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« Reply #2 on: June 10, 2013, 10:55:26 PM »
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The 2 cars I've ran into this on is a mk4 r32, and 225 tt that I converted to wideband and has a mk4 jetta ecu
with a UNImafless file it was UNI that pointed this out while I was trying to fix a hot start problem with the car.
The problem turned out to be a ECU same file different ecu car starts great now. One of the tuners over there
pointed me to the rear o2 not being hooked up could be the problem I was like how? That is the story I got.
I also had a mk4 r32 that would go into softlimp? Now why have limp mode for a rear o2?
I'm also trying to figure out how or if you can make a Mk4 r32 use single rear o2 like the s4.
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prj
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« Reply #3 on: June 11, 2013, 12:05:09 AM »
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Rear O2 is used for slight secondary correction, but if coded out properly then it is not needed.
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ABCD
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« Reply #4 on: June 11, 2013, 12:55:03 AM »
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Rear O2s are basically for catalyst degradation monitoring.
How can they be used for fuel correction?
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ddillenger
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« Reply #5 on: June 11, 2013, 01:07:02 AM »
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The v6 uses them for rear lambda control (see CW CLRHK), but I've never seen that, or any comparable CW in the 4cyl files.
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CoupedUp
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« Reply #6 on: June 11, 2013, 07:28:50 AM »
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Rear O2s are basically for catalyst degradation monitoring.
How can they be used for fuel correction?
What do you think would be adjusted for catalyst degradation? Your AFR, that's what. Fuel injection, combustion efficiency and catalyst efficiency all play a role on the AFR. Your ECU is trying to meet EPA standards so when combustion efficiency(albeit almost negligible) and/or catalyst efficiency degrade the only tool your ECU has is fuel correction. |
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Carsinc
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« Reply #7 on: June 11, 2013, 08:00:10 AM »
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Rear O2 is used for slight secondary correction, but if coded out properly then it is not needed.
This is what I was thinking, but nobody I've talked to can do it. I mean no rear 02sensor in the car yet no problem with long term adaptation or a soft limp. I'm swapping a mk4 r32 motor and would love to delete both rear o2 completely. I'm still trying to find a definition file for the ecu. |
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vdubnation
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« Reply #8 on: June 11, 2013, 08:03:14 AM »
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This is what I was thinking, but nobody I've talked to can do it. I mean no rear 02sensor in the car yet no problem with
long term adaptation or a soft limp.
I'm swapping a mk4 r32 motor and would love to delete both rear o2 completely. I'm still trying to find a definition file for the ecu.
there is a really good damos floating around |
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Carsinc
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« Reply #9 on: June 11, 2013, 10:12:02 AM »
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there is a really good damos floating around
Yes but I have not found it, I know it on another forum of which I am not a member, maybe a pm? Somebody here has it I'm sure I'm willing to try to make a XDF from it and then share that up here. |
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ddillenger
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« Reply #10 on: June 11, 2013, 10:15:57 AM »
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Yes but I have not found it, I know it on another forum of which I am not a member, maybe a pm?
Somebody here has it I'm sure I'm willing to try to make a XDF from it and then share that up here.
http://nefariousmotorsports.com/forum/index.php?topic=3469.0 |
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Please, ask all questions on the forums! Doing so will ensure the next person with the same issue gets the opportunity to learn from your experience!
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Carsinc
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« Reply #11 on: June 11, 2013, 10:33:58 AM »
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I think that may be the wrong link? |
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NOTORIOUS VR
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« Reply #12 on: June 11, 2013, 10:35:45 AM »
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I think that may be the wrong link?
No it's there a few posts down |
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Carsinc
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« Reply #13 on: June 11, 2013, 10:46:05 AM »
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I found it, sorry I'm stupid.
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ABCD
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« Reply #14 on: June 11, 2013, 09:01:50 PM »
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What do you think would be adjusted for catalyst degradation? Your AFR, that's what. Fuel injection, combustion efficiency and catalyst efficiency all play a role on the AFR. Your ECU is trying to meet EPA standards so when combustion efficiency(albeit almost negligible) and/or catalyst efficiency degrade the only tool your ECU has is fuel correction.
Thank you! |
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