Help! LTFT at -14 on TSP1 with K&N Intake

[gtman]

Alex, I looked at the datalog in Flashpro Manager and your trims looked much better than the numbers you mentioned earlier. LTFT was mostly anywhere from -2 to -7 from what I saw. STFT was OK too. You had a couple of large negative spikes but that's how STFT is. Nothing to worry about. You're running slightly rich but nothing bad at all, honestly. You could use some fine tuning of you AFM if you want but you certainly can drive safely as is. All your other numbers like AFR, K.Control, IAT's etc. were great.

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[Alex_hockey69]

@Alex_hockey69 you are running rich brother

yes that I realied

Alex, I looked at the datalog in Flashpro Manager and your trims looked much better than the numbers you mentioned earlier. LTFT was anywhere from -2 to -7 max. STFT was OK too. You had a couple of large negative spikes but that's how STFT is. Nothing to worry about. You're running slightly rich but nothing bad at all, honestly. You could use some fine tuning of you AFM if you want but you certainly can drive safely as is. All your other numbers like AFR, K.Control, IAT's etc. were great.

[/QUOTE

The LTFT goes higher though -12 was the highest

 

[fenix-silver]

I’m still upset I bought an intake that literally flows less than stock apparently. Makes no sense how a K&N cone filter flows less than than stock. Wtf how can they claim gains?

It's not that some of these aftermarket intakes flow less than stock, it's that they don't do any real testing to make sure the airflow through the MAF housing isn't being disrupted in a way that throws off how the MAF sensor is calibrated with the ECU. Things like joints in the intake, rough edges, etc. can make the air flow a bit differently than how the stock intake flows and this can throw off the MAF sensor readings. Even manufacturing differences in the OEM intake will have an impact, which is why you have things like fuel trims to allow the ECU to automatically account for these types of things. Ideally you want the LTFT to hover around 0% like others have mentioned, which gives the ECU plenty of leeway to make adjustments + or -. Coming from the Subaru world, it was generally advised to rescale your MAF for ANY aftermarket intake, which of course most people never did, and then wondered why their engines went boom from running a poorly scaled intake.

 

[Alex_hockey69]

It's not that some of these aftermarket intakes flow less than stock, it's that they don't do any real testing to make sure the airflow through the MAF housing isn't being disrupted in a way that throws off how the MAF sensor is calibrated with the ECU. Things like joints in the intake, rough edges, etc. can make the air flow a bit differently than how the stock intake flows and this can throw off the MAF sensor readings. Even manufacturing differences in the OEM intake will have an impact, which is why you have things like fuel trims to allow the ECU to automatically account for these types of things. Ideally you want the LTFT to hover around 0% like others have mentioned, which gives the ECU plenty of leeway to make adjustments + or -. Coming from the Subaru world, it was generally advised to rescale your MAF for ANY aftermarket intake, which of course most people never did, and then wondered why their engines went boom from running a poorly scaled intake.

When you said rescale your MAF. You mean your fuel trims? sorry I am a newbie at this and I recently installed a k&N short ram and my long-term fuel trims are way off

 

[fenix-silver]

When you said rescale your MAF. You mean your fuel trims? sorry I am a newbie at this and I recently installed a k&N short ram and my long-term fuel trims are way off

MAF scaling affects fuel trims. The MAF sensor puts out a voltage which the ECU interprets as a certain amount of airflow. If the MAF scaling is off, the engine will be getting more or less air than anticipated, which will show up as a fuel trim that is above or below 0. That is why you rescale the MAF to account for a new intake. Basically you are logging a bunch of MAF values and the corresponding AFR vs target AFR. The % difference between AFR and target AFR is how much that MAF value needs to be adjusted to get the true airflow for that MAF value. You aren't doing anything to the fuel trims themselves. Fuel trims are the end result.

 

[Burgerstandman]

It's not that some of these aftermarket intakes flow less than stock, it's that they don't do any real testing to make sure the airflow through the MAF housing isn't being disrupted in a way that throws off how the MAF sensor is calibrated with the ECU. Things like joints in the intake, rough edges, etc. can make the air flow a bit differently than how the stock intake flows and this can throw off the MAF sensor readings. Even manufacturing differences in the OEM intake will have an impact, which is why you have things like fuel trims to allow the ECU to automatically account for these types of things. Ideally you want the LTFT to hover around 0% like others have mentioned, which gives the ECU plenty of leeway to make adjustments + or -. Coming from the Subaru world, it was generally advised to rescale your MAF for ANY aftermarket intake, which of course most people never did, and then wondered why their engines went boom from running a poorly scaled intake.

That makes more sense, thanks for that. I got my LTFT pretty close to 0% now eventually get to -3 but man that’s so much better. I think my car is much happier now.

 

[Burgerstandman]

I hear ya. I take intake manufacturer power gain claims with a grain of salt. It's not sexy, but the stock airbox does a pretty good job overall.

Does this look ok? I go lean a couple times is that bad? Is it better to stay a little rich?

@NikkoPH @gtman

 

[Alex_hockey69]

That makes more sense, thanks for that. I got my LTFT pretty close to 0% now eventually get to -3 but man that’s so much better. I think my car is much happier now.

Please explain to me what you did we both have the same problem and we both have the same setup I just don't understand what tables... Scales... I have to adjust

 

[Burgerstandman]

Please explain to me what you did we both have the same problem and we both have the same setup I just don't understand what tables... Scales... I have to adjust

Ok so go to your tune and click “sensors” you will see the MAF sensor pop up.

Click on that and you”ll see a table with g/s and HZ you will be adjusting the G/S (bottom row)

Now that you have that up click “window” at the top and select the advance x/y graph. Bring up your fuel trims.

(Reference other people’s graph pics above to copy how to set it up.)

Now looking at the graph let’s say at 1g/s your at -8 STFT click the 1G/s square and then right click.

Then click “adjust” then type -8 in the top “adjust by percent Box” And then click “ok”.

In theory that section (1g/s) should be very close to 0% at this point.

Now go through your graph to every G/S 1 through 30 adjusting where it goes negative the most.

Then upload, Data Log, rinse and repeat until you see your graph get closer to 0%

That’s the best I can do right now for you. My wife is mad that I’ve been Messing with this all week otherwise I would attach pictures so you can see exactly what I did sorry. I hope this somewhat helps! I should be able to post more later possibly. Depends when my wife falls asleep lol

 

[Alex_hockey69]

Ok so go to your tune and click “sensors” you will see the MAF sensor pop up.

Click on that and you”ll see a table with g/s and HZ you will be adjusting the G/S (bottom row)

Now that you have that up click “window” at the top and select the advance x/y graph. Bring up your fuel trims.

(Reference other people’s graph pics above to copy how to set it up.)

Now looking at the graph let’s say at 1g/s your at -8 STFT click the 1G/s square and then right click.

Then click “adjust” then type -8 in the top “adjust by percent Box” And then click “ok”.

In theory that section (1g/s) should be very close to 0% at this point.

Now go through your graph to every G/S 1 through 30 adjusting where it goes negative the most.

Then upload, Data Log, rinse and repeat until you see your graph get closer to 0%

That’s the best I can do right now for you. My wife is mad that I’ve been Messing with this all week otherwise I would attach pictures so you can see exactly what I did sorry. I hope this somewhat helps! I should be able to post more later possibly. Depends when my wife falls asleep lol

Thank you I really appreciate it! I will try and do it later when I get back from work

 

[Neddih]

If my LTFT starts at 3.13, peaks at 6.00 and is back down to 4.7 at the end of a log does that seem like an issue? I am going to run a better log later today or this week but from the partial I recorded that is what I saw... AFR averaged around 15 also.

 

[fenix-silver]

If my LTFT starts at 3.13, peaks at 6.00 and is back down to 4.7 at the end of a log does that seem like an issue? I am going to run a better log later today or this week but from the partial I recorded that is what I saw... AFR averaged around 15 also.

I assume during the log you are doing a hard pull or two? If so, the fact that the LTFT is increasing during hard pulls means that things are running lean at high loads so the ECU is adding fuel. Not ideal, IMO. Average AFR is pretty meaningless since you'll likely always average around 14.7. The important part is monitoring AFR vs target AFR.

 

[Jes_si562]

Ok so go to your tune and click “sensors” you will see the MAF sensor pop up.

Click on that and you”ll see a table with g/s and HZ you will be adjusting the G/S (bottom row)

Now that you have that up click “window” at the top and select the advance x/y graph. Bring up your fuel trims.

(Reference other people’s graph pics above to copy how to set it up.)

Now looking at the graph let’s say at 1g/s your at -8 STFT click the 1G/s square and then right click.

Then click “adjust” then type -8 in the top “adjust by percent Box” And then click “ok”.

In theory that section (1g/s) should be very close to 0% at this point.

Now go through your graph to every G/S 1 through 30 adjusting where it goes negative the most.

Then upload, Data Log, rinse and repeat until you see your graph get closer to 0%

That’s the best I can do right now for you. My wife is mad that I’ve been Messing with this all week otherwise I would attach pictures so you can see exactly what I did sorry. I hope this somewhat helps! I should be able to post more later possibly. Depends when my wife falls asleep lol

Did you adjust the MAF scaling on the tsp tune???

 

[Neddih]

I assume during the log you are doing a hard pull or two? If so, the fact that the LTFT is increasing during hard pulls means that things are running lean at high loads so the ECU is adding fuel. Not ideal, IMO. Average AFR is pretty meaningless since you'll likely always average around 14.7. The important part is monitoring AFR vs target AFR.

Yeah I did do a few hard pulls so I could see what the log would show. So an ideal scenario would be that even during a hard pull you should not see an increase in LTFT? Sorry, i'm just trying to understand because I know the numbers aren't high but from
my noob perspective I would have expected the outcome from my log where the engine is using more fuel during a hard pull lol. I guess I will try to re-scale my MAF if its possible in TSP stage 1, since I do have the 27Won intake.

Also if anyone has any good reading material for the subject please PM it to me, I haven't been able to find anything really explaining it well.

 

[fenix-silver]

Yeah I did do a few hard pulls so I could see what the log would show. So an ideal scenario would be that even during a hard pull you should not see an increase in LTFT? Sorry, i'm just trying to understand because I know the numbers aren't high but from
my noob perspective I would have expected the outcome from my log where the engine is using more fuel during a hard pull lol. I guess I will try to re-scale my MAF if its possible in TSP stage 1, since I do have the 27Won intake.

Also if anyone has any good reading material for the subject please PM it to me, I haven't been able to find anything really explaining it well.

If you want to go down a rathole, even though it's specific to Subaru, this guide has lots of pertinent info on MAF based fueling: https://docs.google.com/viewer?a=v&...iaWV0dW5pbmdndWlkZXxneDoxMGYzM2M5NjBlYzY3ODI4

The reason the LTFT increases isn't due to the ECU commanding more fuel because you are giving more throttle, but because the AFR is leaner than expected so the ECU is commanding more fuel to get to the target AFR. Hopefully someone with detail knowledge of Honda ECUs will chime in, but in the Subaru world the fuel trims were never affected by open loop fueling. From that tuning document:

CLOSED LOOP
Let's start with closed loop fueling. The goal of closed loop fueling is to have the car run the stoich
AFR. It does this, like it does everything else, by using guess and check. As you drive, a known amount
of fuel is being used. After it is burned, the exhaust gases are analyzed by the O2 sensor to see if there is
any oxygen left in the exhaust. If there isn't, the ECU thinks you are running rich (too much fuel and not
enough air, AFR lower then 14.7) so it lessens the amount of fuel it is squirting into the engine. When it
sees oxygen in the air, it thinks it's running lean (AFR higher then 14.7) and adds more fuel. It does this
really fast and only adjusts the fuel a little bit as needed thus giving you an avarage14.7 AFR. Easy.
Note:
For those that have widebands, you will notice that your AFRs bounce around a bit while you’re in CL
fueling. This is normal behaviour and is meant to help the catalytic converters.
OPEN LOOP
There are times when we want our car to not run the stoich AFR. This would be when we are trying to
make a lot of power by compressing the air/fuel mixture as much as possible before the spark plug
ignites it. So what AFR should we run? A 12:1 AFR is good for power, but dangerous to the engine. It
would be good for an aggressive tune on a car that you won't mind if the engine goes. The more reliable
AFRs of 10.5:1 to 11:1 for a TMIC and 11:1 to 11.5:1 for an fmic are usually used on a daily driver.
The tricky part is figuring out how much fuel you need since there is no feedback. This is where your Mass Air Flow sensor comes in. The MAF is just a heated wire. The ecu tries to keep that wire heated
to a certain temperature, but as air flows over the wire, it cools it. So the more air that is sucked into the
engine, the more voltage will be required to keep the wire at the set temperature. So that voltage can be
mapped to a given amount of grams of air per second going into the engine. So, for example, if the
MAF sees 2.6 volts, then the ecu knows the engine is eating 126 grams of air per second. Knowing this,
the ECU looks at what AFR you want to run, takes into account any necessary compensations, and
determines an injector pulse width to give you the AFR you’re looking for. The pulse width is the
amount of time the injector is open and (along with the fuel pressure) determines how much fuel gets
squirted into the engine. As you can see, the ECU never knows what the real AFR is while in open
loop. It’s up to the tuner to determine what AFR the car should be running and setup the ECU
parameters to make the actual and requested AFRs match up.

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