how much will the ecu try to adjust the fuel while in closed loop
07-22-2005
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how much will the ecu try to adjust the fuel while in closed loop After reading all the info on honda tech about how obd2 will adjust fuel in closed loop, I just want to know, for all you ppl who have turbo, how do u guys get around it? (I personally reset my ecu every 4 days). Is there any other options beside split second esc1 or getting standalong?? or, just leave it as it is and assume the a/f that we tune at by using piggy back is beyond stock ecu's control??
thx
thx
07-22-2005
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it will compensate +- 20%
It only compensates at part throttle. When you got WOT, it takes the last known correction, and locks it in. So if you are cruising, and the correction is -15%, then you punch it, that value is locked in. So you are losing fuel and running leaner.
But the opposite is also possible. It can run very rich by adding up to 20% at times as well.
This is why people's dyno graphs are always different.
You have to tune each individual car for fuel trims, keeping them as low as possible at all times. Once you do that, you will have more consistent fuel curves.
It only compensates at part throttle. When you got WOT, it takes the last known correction, and locks it in. So if you are cruising, and the correction is -15%, then you punch it, that value is locked in. So you are losing fuel and running leaner.
But the opposite is also possible. It can run very rich by adding up to 20% at times as well.
This is why people's dyno graphs are always different.
You have to tune each individual car for fuel trims, keeping them as low as possible at all times. Once you do that, you will have more consistent fuel curves.
07-22-2005
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Rep Power: 272 I hated the piggy backed stock ecu. I never could get it to stay consistent. Every day it was a surprise. CELs running rich, lean, not at all. hehe I got an ex ecu if anyone wants it.. Maybe Ill torture it to death like it did to me.
07-22-2005
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Rep Power: 0 thx for the input. Then, how can we tune partial throttle? I am worried that if ecu try to compensate fuel to desired a/f ratio(maybe 14.7) at partial throttle while boosting, won't it be too lean during boosting?
thx again
thx again
07-22-2005
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Rep Power: 260 you have to use a scanner to look at the long term and short term fuel trims, and spend hours screwing with fuel settings to try to get the fuel trims as close to zero as possible. While screwing with the fuel trims, do not tune using the wideband. While at part throttle, give the computer the a/f it wants. It is normally safe to run it a little leaner while you are only under partial load. When you go WOT, that is when you need the fuel. And thats why you have to get the fuel trims right.
07-22-2005
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Originally Posted by turboengnr
you have to use a scanner to look at the long term and short term fuel trims, and spend hours screwing with fuel settings to try to get the fuel trims as close to zero as possible. While screwing with the fuel trims, do not tune using the wideband. While at part throttle, give the computer the a/f it wants. It is normally safe to run it a little leaner while you are only under partial load. When you go WOT, that is when you need the fuel. And thats why you have to get the fuel trims right.
07-22-2005
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Rep Power: 260 you tune with a wideband at WOT. If you use a wideband to tune at part throttle, the computer will compensate and adjust the fuel to where it wants it. Then when you actually do to full throttle, the value that the computer has locked in will transfer over to the WOT setting, and it will mess with your tune. The computer has a "fuel trim" feature that can add or remove 20% of the injector pulsewidth. That means that if you are running an a/f ratio of 11.3 on one pass (lets say the fuel trim was at +12% this pass), then the next pass could be in the mid to high 13's with a fuel trim of -20%.
You have to tune the car under ALL LOAD AND ALL RPM VALUES! If you do not do this, then you will most likely have fuel trim issues.
You have to tune the car under ALL LOAD AND ALL RPM VALUES! If you do not do this, then you will most likely have fuel trim issues.
07-22-2005
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Originally Posted by turboengnr
you tune with a wideband at WOT. If you use a wideband to tune at part throttle, the computer will compensate and adjust the fuel to where it wants it. Then when you actually do to full throttle, the value that the computer has locked in will transfer over to the WOT setting, and it will mess with your tune. The computer has a "fuel trim" feature that can add or remove 20% of the injector pulsewidth. That means that if you are running an a/f ratio of 11.3 on one pass (lets say the fuel trim was at +12% this pass), then the next pass could be in the mid to high 13's with a fuel trim of -20%.
You have to tune the car under ALL LOAD AND ALL RPM VALUES! If you do not do this, then you will most likely have fuel trim issues.
You have to tune the car under ALL LOAD AND ALL RPM VALUES! If you do not do this, then you will most likely have fuel trim issues.
07-22-2005
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Originally Posted by turboengnr
you tune with a wideband at WOT. If you use a wideband to tune at part throttle, the computer will compensate and adjust the fuel to where it wants it. Then when you actually do to full throttle, the value that the computer has locked in will transfer over to the WOT setting, and it will mess with your tune. The computer has a "fuel trim" feature that can add or remove 20% of the injector pulsewidth. That means that if you are running an a/f ratio of 11.3 on one pass (lets say the fuel trim was at +12% this pass), then the next pass could be in the mid to high 13's with a fuel trim of -20%.
You have to tune the car under ALL LOAD AND ALL RPM VALUES! If you do not do this, then you will most likely have fuel trim issues.
You have to tune the car under ALL LOAD AND ALL RPM VALUES! If you do not do this, then you will most likely have fuel trim issues.
Well, im deffinately a N00B when it comes to e-manage tunning for sure. But if you have the tiem could you possibly explain How to tune by watching the fuel trim?
07-22-2005
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Rep Power: 260 no prob
it is actually quite simple.
you need some sort of OBDII scanner that has a data streaming capability.
When you have that, set it up to watch the LT_Ftrm and the ST_Ftrm (long and short term fuel trims). When you have that, you need to have your laptop setup to watch your fuel tables in real time.
When you have those set up, you need to start cruising at low RPM (around 2k) and then start accellerating with a specific amount of throttle. You then watch both the fuel trims on the scanner and the fuel map on the laptop. When you see the fuel trims start to add or subtract fuel, you do the same on the fuel map.
so lets say you are at 3250 RPM and the scanner shows a LT_Ftrm of -2% and a ST_Ftrm of -14%. You should gradually take out fuel in the fuel map until the fuel trims come back down to around zero.
The difference between the LT_Ftrm and the ST_Ftrm is simple. The ST_Ftrm's are what the computer is doing at that specific point in time. The LT_Ftrm is the trend that the computer is seeing.
You know how they say your computer "learns"? Well, they are talking about the LT_Ftrm. Over time, the computer averages out the data it recieves and outputs it as a single variable (LT_Ftrm). When this is at or close to 0%, that means that you spend most the time with a 0% fuel trim correction factor.
When you disconnect the battery, this is the value that gets erased and must be "re-learned" in order for the car to run at its potential.
Typically i like to see fuel trims between +5% and -5% on the LT_Ftrm.
it is actually quite simple.
you need some sort of OBDII scanner that has a data streaming capability.
When you have that, set it up to watch the LT_Ftrm and the ST_Ftrm (long and short term fuel trims). When you have that, you need to have your laptop setup to watch your fuel tables in real time.
When you have those set up, you need to start cruising at low RPM (around 2k) and then start accellerating with a specific amount of throttle. You then watch both the fuel trims on the scanner and the fuel map on the laptop. When you see the fuel trims start to add or subtract fuel, you do the same on the fuel map.
so lets say you are at 3250 RPM and the scanner shows a LT_Ftrm of -2% and a ST_Ftrm of -14%. You should gradually take out fuel in the fuel map until the fuel trims come back down to around zero.
The difference between the LT_Ftrm and the ST_Ftrm is simple. The ST_Ftrm's are what the computer is doing at that specific point in time. The LT_Ftrm is the trend that the computer is seeing.
You know how they say your computer "learns"? Well, they are talking about the LT_Ftrm. Over time, the computer averages out the data it recieves and outputs it as a single variable (LT_Ftrm). When this is at or close to 0%, that means that you spend most the time with a 0% fuel trim correction factor.
When you disconnect the battery, this is the value that gets erased and must be "re-learned" in order for the car to run at its potential.
Typically i like to see fuel trims between +5% and -5% on the LT_Ftrm.
07-23-2005
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Originally Posted by turboengnr
no prob
it is actually quite simple.
you need some sort of OBDII scanner that has a data streaming capability.
When you have that, set it up to watch the LT_Ftrm and the ST_Ftrm (long and short term fuel trims). When you have that, you need to have your laptop setup to watch your fuel tables in real time.
When you have those set up, you need to start cruising at low RPM (around 2k) and then start accellerating with a specific amount of throttle. You then watch both the fuel trims on the scanner and the fuel map on the laptop. When you see the fuel trims start to add or subtract fuel, you do the same on the fuel map.
so lets say you are at 3250 RPM and the scanner shows a LT_Ftrm of -2% and a ST_Ftrm of -14%. You should gradually take out fuel in the fuel map until the fuel trims come back down to around zero.
The difference between the LT_Ftrm and the ST_Ftrm is simple. The ST_Ftrm's are what the computer is doing at that specific point in time. The LT_Ftrm is the trend that the computer is seeing.
You know how they say your computer "learns"? Well, they are talking about the LT_Ftrm. Over time, the computer averages out the data it recieves and outputs it as a single variable (LT_Ftrm). When this is at or close to 0%, that means that you spend most the time with a 0% fuel trim correction factor.
When you disconnect the battery, this is the value that gets erased and must be "re-learned" in order for the car to run at its potential.
Typically i like to see fuel trims between +5% and -5% on the LT_Ftrm.
it is actually quite simple.
you need some sort of OBDII scanner that has a data streaming capability.
When you have that, set it up to watch the LT_Ftrm and the ST_Ftrm (long and short term fuel trims). When you have that, you need to have your laptop setup to watch your fuel tables in real time.
When you have those set up, you need to start cruising at low RPM (around 2k) and then start accellerating with a specific amount of throttle. You then watch both the fuel trims on the scanner and the fuel map on the laptop. When you see the fuel trims start to add or subtract fuel, you do the same on the fuel map.
so lets say you are at 3250 RPM and the scanner shows a LT_Ftrm of -2% and a ST_Ftrm of -14%. You should gradually take out fuel in the fuel map until the fuel trims come back down to around zero.
The difference between the LT_Ftrm and the ST_Ftrm is simple. The ST_Ftrm's are what the computer is doing at that specific point in time. The LT_Ftrm is the trend that the computer is seeing.
You know how they say your computer "learns"? Well, they are talking about the LT_Ftrm. Over time, the computer averages out the data it recieves and outputs it as a single variable (LT_Ftrm). When this is at or close to 0%, that means that you spend most the time with a 0% fuel trim correction factor.
When you disconnect the battery, this is the value that gets erased and must be "re-learned" in order for the car to run at its potential.
Typically i like to see fuel trims between +5% and -5% on the LT_Ftrm.
VERY informative! Thanx
07-23-2005
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Rep Power: 0 so, couldn't you just disconnect your battery all the time so it doesn't "learn" anything differnt than what you tune it too?
i.e you disconnect you battery and then tune you car. and then everytime you take it out you disconnect your battery again. that way your always starting at the same point?
if so, is there an easier way to reset the learned fuel trims? maybe an OBDII scantool?
i.e you disconnect you battery and then tune you car. and then everytime you take it out you disconnect your battery again. that way your always starting at the same point?
if so, is there an easier way to reset the learned fuel trims? maybe an OBDII scantool?
07-23-2005
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Rep Power: 260 no, because when you disconnect the battery, it automatically starts learning everything. It then programs the long term fuel trims and updates is constantly. It can change the long term every second or more within the first few minutes of driving.
07-24-2005
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Rep Power: 0 Then, I don't see how any piggy back could help on a daily driven car if it will do what it wants to, even using a +40% setting if it locked a -15% it will make you run lean at WOT.
Then why spend money on piggy backs???
Please right me, I know I have to be wrong but I can't see how those piggy backs could help then or how to do the tuning in a way that the ECU won't bother?
Then why spend money on piggy backs???
Please right me, I know I have to be wrong but I can't see how those piggy backs could help then or how to do the tuning in a way that the ECU won't bother?
07-24-2005
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Rep Power: 260 because you can still tune at WOT. You just need to have the proper tuning during the non-WOT part of the map.
once you get the fuel trims dialed in, you will have an extremely consistent a/f curve.
once you get the fuel trims dialed in, you will have an extremely consistent a/f curve.
07-24-2005
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Rep Power: 787 so is there a right or wrong way to relearn on an NA car after resetting the ecu? Do you need to drive a certain way? And when tuning using a vafc, I guess you can only do wot settings?
07-24-2005
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Rep Power: 303 Ijust watched short term and long term on my car. Short term changes a lot and the long term didnt seem to change much so that would mean its in good tune?
07-24-2005
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Originally Posted by turboengnr
no prob
it is actually quite simple.
you need some sort of OBDII scanner that has a data streaming capability.
When you have that, set it up to watch the LT_Ftrm and the ST_Ftrm (long and short term fuel trims). When you have that, you need to have your laptop setup to watch your fuel tables in real time.
When you have those set up, you need to start cruising at low RPM (around 2k) and then start accellerating with a specific amount of throttle. You then watch both the fuel trims on the scanner and the fuel map on the laptop. When you see the fuel trims start to add or subtract fuel, you do the same on the fuel map.
so lets say you are at 3250 RPM and the scanner shows a LT_Ftrm of -2% and a ST_Ftrm of -14%. You should gradually take out fuel in the fuel map until the fuel trims come back down to around zero.
The difference between the LT_Ftrm and the ST_Ftrm is simple. The ST_Ftrm's are what the computer is doing at that specific point in time. The LT_Ftrm is the trend that the computer is seeing.
You know how they say your computer "learns"? Well, they are talking about the LT_Ftrm. Over time, the computer averages out the data it recieves and outputs it as a single variable (LT_Ftrm). When this is at or close to 0%, that means that you spend most the time with a 0% fuel trim correction factor.
When you disconnect the battery, this is the value that gets erased and must be "re-learned" in order for the car to run at its potential.
Typically i like to see fuel trims between +5% and -5% on the LT_Ftrm.
it is actually quite simple.
you need some sort of OBDII scanner that has a data streaming capability.
When you have that, set it up to watch the LT_Ftrm and the ST_Ftrm (long and short term fuel trims). When you have that, you need to have your laptop setup to watch your fuel tables in real time.
When you have those set up, you need to start cruising at low RPM (around 2k) and then start accellerating with a specific amount of throttle. You then watch both the fuel trims on the scanner and the fuel map on the laptop. When you see the fuel trims start to add or subtract fuel, you do the same on the fuel map.
so lets say you are at 3250 RPM and the scanner shows a LT_Ftrm of -2% and a ST_Ftrm of -14%. You should gradually take out fuel in the fuel map until the fuel trims come back down to around zero.
The difference between the LT_Ftrm and the ST_Ftrm is simple. The ST_Ftrm's are what the computer is doing at that specific point in time. The LT_Ftrm is the trend that the computer is seeing.
You know how they say your computer "learns"? Well, they are talking about the LT_Ftrm. Over time, the computer averages out the data it recieves and outputs it as a single variable (LT_Ftrm). When this is at or close to 0%, that means that you spend most the time with a 0% fuel trim correction factor.
When you disconnect the battery, this is the value that gets erased and must be "re-learned" in order for the car to run at its potential.
Typically i like to see fuel trims between +5% and -5% on the LT_Ftrm.
07-24-2005
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Originally Posted by turboengnr
what was the long term like? Was it between -5% and +5%?
to make it relearn correctly, drive the car like you normally do.
to make it relearn correctly, drive the car like you normally do.
07-24-2005
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Rep Power: 260 leon, you are partially correct.
But one aspect that you need to look at is what a/f ratio the car is looking for under load. I know when i was at ~75% throttle with my car NA, the car ran in the mid 12's a/f. The car knows when it needs to be lean and when it needs to be rich.
The problem with resetting it every few days is this....
when you let it learn everything, it takes a while for anything to change the LT_Ftrm's,. When you reset the ecu, it updates it constantly.
but as long as your ST_Ftrm is constantly out of a desired range, then you need to tune to bring those within the limits.
But one aspect that you need to look at is what a/f ratio the car is looking for under load. I know when i was at ~75% throttle with my car NA, the car ran in the mid 12's a/f. The car knows when it needs to be lean and when it needs to be rich.
The problem with resetting it every few days is this....
when you let it learn everything, it takes a while for anything to change the LT_Ftrm's,. When you reset the ecu, it updates it constantly.
but as long as your ST_Ftrm is constantly out of a desired range, then you need to tune to bring those within the limits.
