Fuel Trims only 0.75 during cold start-ups?!?
#16
03-08-2018, 02:18 AM
Join Date: Oct 2010
Location: Maryland
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We can't be sure about anything with only one readout.
You need to look at start time, then midway through the temperature rise , then at full running temperature.
If you are not having any cold start issues as the tables shift vs temperature , then leave well enough alone.
If they are near zero or neutral as designed to run on a near perfect system and react to shifting rich on acceleration, that's all you can get.
What would you do the change it and what would you like to see?
How do you know the program your running on has not been altered?
The SCT device you have provoked the question!
It being a 4.2 may be programmed different than V8. It is a smaller displacement motor.
On my 4.6 the short tables shift to about 4% +/- depending on the ambient outside temperature, then shift back toward zero and hunt as the Ox sensors signals dictate.
They are never static at zero any more than the Ox senors voltages do not stay stable but hunt according to the exhaust Ox content from each cylinder.
The long tables could be any value depending on the system health and ideally Zero on a perfect engine.
Good luck.
You need to look at start time, then midway through the temperature rise , then at full running temperature.
If you are not having any cold start issues as the tables shift vs temperature , then leave well enough alone.
If they are near zero or neutral as designed to run on a near perfect system and react to shifting rich on acceleration, that's all you can get.
What would you do the change it and what would you like to see?
How do you know the program your running on has not been altered?
The SCT device you have provoked the question!
It being a 4.2 may be programmed different than V8. It is a smaller displacement motor.
On my 4.6 the short tables shift to about 4% +/- depending on the ambient outside temperature, then shift back toward zero and hunt as the Ox sensors signals dictate.
They are never static at zero any more than the Ox senors voltages do not stay stable but hunt according to the exhaust Ox content from each cylinder.
The long tables could be any value depending on the system health and ideally Zero on a perfect engine.
Good luck.
The SCT device I am utilizing has been programmed with all the specifics including 4.2 V-6, auto, 2wd, gear ratios, tire size, exhaust and intake modifications, ect. It is very application specific and I have verified all settings.
#17
03-08-2018, 12:40 PM
#18
03-08-2018, 12:41 PM
#19
03-08-2018, 03:52 PM
Hotshot
1. It is completely normal for the trims to be fixed and a bit rich during cold engine startup. That's a programmed behavior. You have to wait for the system to go into closed-loop operation before the computer starts adjusting trims based on the O2 sensor data
2. Use a real scan tool or equivalent, not a tuner, for in-depth diagnostics. The tuner is limited on what it can do and it appears yours is presenting data in a rather non-standard way which is increasing confusion.
Bottom line, I think you're chasing a ghost due to your tuner's data format and your misunderstanding of what to expect. Next time you get a MIL, use the scan tool to read the freeze frame data so you see what the operating conditions were when the DTC was posted. That helps narrow down the possibilities and reduces guessing (along with wasted time and money).
2. Use a real scan tool or equivalent, not a tuner, for in-depth diagnostics. The tuner is limited on what it can do and it appears yours is presenting data in a rather non-standard way which is increasing confusion.
Bottom line, I think you're chasing a ghost due to your tuner's data format and your misunderstanding of what to expect. Next time you get a MIL, use the scan tool to read the freeze frame data so you see what the operating conditions were when the DTC was posted. That helps narrow down the possibilities and reduces guessing (along with wasted time and money).
#20
03-08-2018, 11:32 PM
At this point it's all confusion.
If your emissions inspection plugs into your DLC port and looks for codes, that all you need if none are set and all PIDS are complete..
They don't normally look at fuel trim data.
If you have program data changed do to mods, it may be a problem especially if you go to a dealer and they see it..
BTW, shorting out the battery leads and leaving power off long term is foolish when it only takes a minute or two to accomplish by either doing a Code Clear, momentary single battery cable disconnect or pulling a PCM fuse and replacing it back in the holder.
Get a regular Scanner, look at what you have and go from there.
We can't tell you about what your tool has in it.
Every time you reboot the computer you clear all tables of auto adjust data. such that you have to do a couple drive cycles to see where the system settles at..
It even has to build the cold start. and hot restart table all over again each time.
Please listen.
Good luck..
.
..
If your emissions inspection plugs into your DLC port and looks for codes, that all you need if none are set and all PIDS are complete..
They don't normally look at fuel trim data.
If you have program data changed do to mods, it may be a problem especially if you go to a dealer and they see it..
BTW, shorting out the battery leads and leaving power off long term is foolish when it only takes a minute or two to accomplish by either doing a Code Clear, momentary single battery cable disconnect or pulling a PCM fuse and replacing it back in the holder.
Get a regular Scanner, look at what you have and go from there.
We can't tell you about what your tool has in it.
Every time you reboot the computer you clear all tables of auto adjust data. such that you have to do a couple drive cycles to see where the system settles at..
It even has to build the cold start. and hot restart table all over again each time.
Please listen.
Good luck..
.
..
#21
03-12-2018, 08:56 AM
Join Date: Oct 2010
Location: Maryland
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#22
03-29-2018, 02:16 AM
Join Date: Oct 2010
Location: Maryland
Posts: 602
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At this point it's all confusion.
If your emissions inspection plugs into your DLC port and looks for codes, that all you need if none are set and all PIDS are complete..
They don't normally look at fuel trim data.
If you have program data changed do to mods, it may be a problem especially if you go to a dealer and they see it..
BTW, shorting out the battery leads and leaving power off long term is foolish when it only takes a minute or two to accomplish by either doing a Code Clear, momentary single battery cable disconnect or pulling a PCM fuse and replacing it back in the holder.
Get a regular Scanner, look at what you have and go from there.
We can't tell you about what your tool has in it.
Every time you reboot the computer you clear all tables of auto adjust data. such that you have to do a couple drive cycles to see where the system settles at..
It even has to build the cold start. and hot restart table all over again each time.
Please listen.
Good luck..
.
..
If your emissions inspection plugs into your DLC port and looks for codes, that all you need if none are set and all PIDS are complete..
They don't normally look at fuel trim data.
If you have program data changed do to mods, it may be a problem especially if you go to a dealer and they see it..
BTW, shorting out the battery leads and leaving power off long term is foolish when it only takes a minute or two to accomplish by either doing a Code Clear, momentary single battery cable disconnect or pulling a PCM fuse and replacing it back in the holder.
Get a regular Scanner, look at what you have and go from there.
We can't tell you about what your tool has in it.
Every time you reboot the computer you clear all tables of auto adjust data. such that you have to do a couple drive cycles to see where the system settles at..
It even has to build the cold start. and hot restart table all over again each time.
Please listen.
Good luck..
.
..
Posted by other users on here, on a thread you were on as well, about the battery cable thing. Just remembered.
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