Good days gurus, please what are the causes of negative fuel trim? On but short term & long term, from my little research online, means the engine is running rich meaning higher fuel consumption, the car is Honda accord 2006 i4, the only MIL code on is catalyst code P0420
Cc Gazzuzz Nurey Honmusa Mayor2013 Kingreign Piyke EgunMogaji

What Fuel Trim Values Mean

POSITIVE fuel trim values mean the engine computer is adding fuel (increasing the pulse width or on-time of the fuel injectors) to add more fuel to the engine. In other words, it is attempting to RICHEN the fuel mixture because it thinks the engine�s air/fuel mixture is running too lean.

NEGATIVE (-) fuel trim values mean the engine computer is subtracting fuel (decreasing the pulse width or on-time of the fuel injectors) to reduce the amount of fuel injected into the engine. This is done to LEAN out the fuel mixture to compensate for what it perceives as a rich running condition.

Remember, all this is based on what the oxygen sensors are telling the engine computer. If the O2 sensors indicate LEAN, the computer adds fuel and generates a POSITIVE fuel trim value. If the O2 sensors are reading RICH, the computer compensates by subtracting fuel and generates a NEGATIVE fuel trim value.

By reading the STFT and LTFT fuel trim values on a scan tool while your engine is running, you can tell if the air/fuel mixture is running rich (negative fuel trim percentages) or lean (positive fuel trim percentages).

What Fuel Trim Values Should Be

Ideally, the STFT and LTFT should be within a few percentage points of zero when the engine is idling or being held at a steady RPM. Remember, STFT can bounce around quite a bit as when you suddenly snap open the throttle or decelerate. But LTFT can tell you if the average fuel/mixture is running rich or lean.

Good LTFT values should be as close to zero as possible, though they can range from 5 to 8 percent depending on the condition of the engine. If the LTFT is getting up around 10 percent or higher, it usually indicates a problem that needs to be diagnosed

Dbkk:
Good days gurus, please what are the causes of negative fuel trim? On but short term & long term, from my little research online, means the engine is running rich meaning higher fuel consumption, the car is Honda accord 2006 i4, the only MIL code on is catalyst code P0420
Cc Gazzuzz Nurey Honmusa Mayor2013 Kingreign Piyke EgunMogaji

I don't bother with FAR at all as it'll lead to gray or loss of hair.

Good fuel, good plugs, etc no CEL and I'm a happy camper.

Dbkk:
Good days gurus, please what are the causes of negative fuel trim? On but short term & long term, from my little research online, means the engine is running rich meaning higher fuel consumption, the car is Honda accord 2006 i4, the only MIL code on is catalyst code P0420
Cc Gazzu.zz Nu.rey Hon.musa Mayor.2013 King.reign Pi.yke Egun.Mogaji

I will address your question soon.

This is an OBD II issue.

I think is is wrong to call that MIL code just.

OBD II considers emissions issues more important than drivability issues.

The catalytic converter is a major part of your vehicle's emission control system.

Expect an in-depth explanation of the issues later.

To help me treat the issues as they affect your vehicle in particular and not just this code in general

Did you buy this vehicle brand new or is it new to you?
What is it's mileage?
How long have you had this problem?
Was any repair made before you had this problem?
Do you have any drivability issues?
Or is the MIL on but no drivability issues/complaints?
Can I have your Freeze Frame Data?
Current Parameter Display information?

If I can have this information, I will personalize the response.

I can see you have your own OBD II Scanner! That's a big plus!!


And subscribe to this thread https://www.nairaland.com/3661728/on-board-diagnostics-obd-ii-questions


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MODIFIED
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Here is what additional information I need to know:

What is the current status of the MIL
1. Do you have no driveability complaint along with the MIL?
2. Do you have driveability complaint(s) along with the MIL? If yes, kindly explain.

Have you ever erased the DTC? Did it come back after that?


Freeze Frame Data required includes:
Fuel System Status (whether Open Loop or Closed Loop)
Calculated Load in Percentage
Short Term Fuel Trim Bank 1 in Percentage
Short Term Fuel Trim Bank 2 in Percentage
Long Term Fuel Trim Bank 1 in Percentage
Long Term Fuel Trim Bank 1 in Percentage
Engine Speed in RPM
Vehicle Speed in MPH or km/h
Engine Coolant Temperature in degrees
If a single-cylinder misfire is detected, indicate cylinder(s)

Current Parameter Display Information required includes:


Fuel System Status (whether Open Loop or Closed Loop)
Calculated Load in Percentage
Short Term Fuel Trim Bank 1 in Percentage
Short Term Fuel Trim Bank 2 in Percentage
Long Term Fuel Trim Bank 1 in Percentage
Long Term Fuel Trim Bank 1 in Percentage
Engine Speed in RPM
Vehicle Speed in MPH or km/h
Engine Coolant Temperature in degrees

We cannot just look at fuel trims in isolation because that is not how the ECU does, it looks at multiple sources of data and then uses them to decide one way or the other, so to solve a problem properly, we have think the way the OBD II system thinks, sort of peek into its mind!

1

EgunMogaji:


I don't bother with FAR at all as it'll lead to gray or loss of hair.

Good fuel, good plugs, etc no CEL and I'm a happy camper.

Hahahaha true that, the car drives fine Sha, no issues.. Was just playing around with my Bluetooth(toy) scanner, when I noticed the fuel trims, decided find out more about it

AutoElectNG:


I will address your question soon.

This is an OBD II issue.

I think is is wrong to call that MIL code just.

OBD II considers emissions issues more important than drivability issues.

The catalytic converter is a major part of your vehicle's emission control system.

Expect an in-depth explanation of the issues later.

To help me treat the issues as they affect your vehicle in particular and not just this code in general

Did you buy this vehicle brand new or is it new to you?
What is it's mileage?
How long have you had this problem?
Was any repair made before you had this problem?
Do you have any drivability issues?
Or is the MIL on but no drivability issues/complaints?
Can I have your Freeze Frame Data?
Current Parameter Display information?

If I can have this information, I will personalize the response.

I can see you have your own OBD II Scanner! That's a big plus!!


And subscribe to this thread https://www.nairaland.com/3661728/on-board-diagnostics-obd-ii-questions

Did you buy this vehicle brand new or is it new to you? Bought it Naija used

What is it's mileage? About 141k

How long have you had this problem? I dunno, I don't usually check fuel trim

Was any repair made before you had this problem? None by me, & no maintenance history base on naija used

Or is the MIL on but no drivability issues/complaints? No drivability issue

Can I have your Freeze Frame Data?
Current Parameter Display information?

If I may come in here the actual values were captured when your car was on motion?

Dbkk:
Good days gurus, please what are the causes of negative fuel trim? On but short term & long term, from my little research online, means the engine is running rich meaning higher fuel consumption, the car is Honda accord 2006 i4, the only MIL code on is catalyst code P0420
Cc Gazzuzz Nurey Honmusa Mayor2013 Kingreign Piyke EgunMogaji

It is quite ok if you have a single digit negative fuel trim ,your car powertrain air fuel mixture is quite ok.What become an issue is if the single digit turns to double digit wether on positive side(lean) or (rich).

Dbkk:



Did you buy this vehicle brand new or is it new to you? Bought it Naija used

What is it's mileage? About 141k

How long have you had this problem? I dunno, I don't usually check fuel trim

Was any repair made before you had this problem? None by me, & no maintenance history base on naija used

Or is the MIL on but no drivability issues/complaints? No drivability issue

Can I have your Freeze Frame Data?
Current Parameter Display information?

Seen.

To be sure that we are absolutely on the same page, please read my last post on this page https://www.nairaland.com/3661728/on-board-diagnostics-obd-ii-questions

I will be back with a detailed response based on the data that you have provided.

honmusa:

It is quite ok if you have a single digit negative fuel trim ,your car powertrain air fuel mixture is quite ok.What become an issue is if the single digit turns to double digit wether on positive side(lean) or (rich).

I have seen it as high as negative 13

mayor2013:
If I may come in here the actual values were captured when your car was on motion?

The first screenshoot were at idle.. But even on motion.. The value fluctuate but mostly on the negative side

Dbkk:


I have seen it as high as negative 13

Typical Honda issue!!!If you can make it to my workshop by next week,I will give u a free diagnosis!!!!

Any misfire on the car? Value for the mass airflow looks high if on idle. Does engine idle well?

nurey:
What Fuel Trim Values Mean

POSITIVE fuel trim values mean the engine computer is adding fuel (increasing the pulse width or on-time of the fuel injectors) to add more fuel to the engine. In other words, it is attempting to RICHEN the fuel mixture because it thinks the engine�s air/fuel mixture is running too lean.

NEGATIVE (-) fuel trim values mean the engine computer is subtracting fuel (decreasing the pulse width or on-time of the fuel injectors) to reduce the amount of fuel injected into the engine. This is done to LEAN out the fuel mixture to compensate for what it perceives as a rich running condition.

Remember, all this is based on what the oxygen sensors are telling the engine computer. If the O2 sensors indicate LEAN, the computer adds fuel and generates a POSITIVE fuel trim value. If the O2 sensors are reading RICH, the computer compensates by subtracting fuel and generates a NEGATIVE fuel trim value.

By reading the STFT and LTFT fuel trim values on a scan tool while your engine is running, you can tell if the air/fuel mixture is running rich (negative fuel trim percentages) or lean (positive fuel trim percentages).

What Fuel Trim Values Should Be

Ideally, the STFT and LTFT should be within a few percentage points of zero when the engine is idling or being held at a steady RPM. Remember, STFT can bounce around quite a bit as when you suddenly snap open the throttle or decelerate. But LTFT can tell you if the average fuel/mixture is running rich or lean.

Good LTFT values should be as close to zero as possible, though they can range from 5 to 8 percent depending on the condition of the engine. If the LTFT is getting up around 10 percent or higher, it usually indicates a problem that needs to be diagnosed

Quote source
http://www.aa1car.com/library/what_is_fuel_trim.htm

mayor2013:
Any misfire on the car? Value for the mass airflow looks high if on idle. Does engine idle well?

No misfire... Engine idles well, btw 800 & 850rpm The screenshot with mass airflow is freeze frame for the P0420 code

Denn:


Quote source
http://www.aa1car.com/library/what_is_fuel_trim.htm

So you are back? Hope not back for more. Am sorry the way I disgraced you in our last race, I meant no harm

It's good to have you back

.

nurey:


So you are back? Hope not back for more. Am sorry the way I disgraced you in our last race, I meant no harm

It's good to have you back

If you term your failing to appear at the race venue a disgrace to me, then yes it was.

Lol.

How every?

Since its less than 10% you may still observe, however I hope your thermostat is not removed and fan running continuously?

Good fuel does affect trim values amognst the other things Egunmogaji listed. I have personally observed significant differences on my vehicle depending on the quality of fuel I get. Too bad we do not know the octane rating of the petrol we drive in this country.

Does your RPM rise sharply on first morning start to 1500 or is the rise a tad sluggish?

Piyke:
Since its less than 10% you may still observe, however I hope your thermostat is not removed and fan running continuously?

Good fuel does affect trim values amognst the other things Egunmogaji listed. I have personally observed significant differences on my vehicle depending on the quality of fuel I get. Too bad we do not know the octane rating of the petrol we drive in this country.

Does your RPM rise sharply on first morning start to 1500 or is the rise a tad sluggish?

RPM Rise sharply at first start around 1500,1600 ish.. Den after sometimes comes down gradually to around 850
Thermostat & ECT2 are intact restored by GAZZUZZ , fan doesn't run continuously

honmusa:

Typical Honda issue!!!If you can make it to my workshop by next week,I will give u a free diagnosis!!!!

Thanks man.. Will appreciate that

Hi Honmusa, my BMW E60 goes into limp mode when trying to gain speed especially when accelerating. It's kinda sluggish now and after scanning I got cylinder 1 misfire.

Earlier before when I got the limp mode, the culprit was the VANOS solenoid which I replaced and solved the issue. Now the error I got before replacing the solenoid has returned. Error is camshaft sensor mechanical and camshaft sensor stiff.

Fuel pump was replaced last month and it really ade the car so snappy and fast but it's now sluggish. What could be cause of the misfire. I was told to fill my fuel tank and buy Mobil fuel treatment first if that would solve it.

Awaiting your response, thanks

Cc mayor2013

honmusa:

Typical Honda issue!!!If you can make it to my workshop by next week,I will give u a free diagnosis!!!!

dillinger:
Hi Honmusa, my BMW E60 goes into limp mode when trying to gain speed especially when accelerating. It's kinda sluggish now and after scanning I got cylinder 1 misfire.

Earlier before when I got the limp mode, the culprit was the VANOS solenoid which I replaced and solved the issue. Now the error I got before replacing the solenoid has returned. Error is camshaft sensor mechanical and camshaft sensor stiff.

Fuel pump was replaced last month and it really ade the car so snappy and fast but it's now sluggish. What could be cause of the misfire. I was told to fill my fuel tank and buy Mobil fuel treatment first if that would solve it.

Awaiting your response, thanks

Cc mayor2013

After scanning ,are u getting only cylinder misfire 1 ?? or with additional with other DTC codes.Pls state all the DTC codes u have for now.

dillinger:
Hi Honmusa, my BMW E60 goes into limp mode when trying to gain speed especially when accelerating. It's kinda sluggish now and after scanning I got cylinder 1 misfire.

Earlier before when I got the limp mode, the culprit was the VANOS solenoid which I replaced and solved the issue. Now the error I got before replacing the solenoid has returned. Error is camshaft sensor mechanical and camshaft sensor stiff.

Fuel pump was replaced last month and it really ade the car so snappy and fast but it's now sluggish. What could be cause of the misfire. I was told to fill my fuel tank and buy Mobil fuel treatment first if that would solve it.


Awaiting your response, thanks

Cc mayor2013

Carry out an engine tune up. What other code (s) do you have

Piyke:
Since its less than 10% you may still observe, however I hope your thermostat is not removed and fan running continuously?

Good fuel does affect trim values amognst the other things Egunmogaji listed. I have personally observed significant differences on my vehicle depending on the quality of fuel I get. Too bad we do not know the octane rating of the petrol we drive in this country.

Does your RPM rise sharply on first morning start to 1500 or is the rise a tad sluggish?

does removing thermostat cause the car to run rich?? With high negative long term trims??

captainking:
does removing thermostat cause the car to run rich?? With high negative long term trims??

Removing thermostat will cause your car to run rich but it might not necessarily show on the fuel trim because it is not a continous event .

autologic:

Removing thermostat will cause your car to run rich but it might not necessarily show on the fuel trim because it is not a continous event .

Oh.. Thanks for the response.. Right now.. I have no oxygen related Codes ..this is the only code I have.... p0128...could this make it run rich? I know you are the guru at such technicalities..but I am not in Lagos to patronize your awesome services..

captainking:

Oh.. Thanks for the response.. Right now.. I have no oxygen related Codes ..this is the only code I have.... p0128...could this make it run rich? I know you are the guru at such technicalities..but I am not in Lagos to patronize your awesome services..

I guess your car is Honda ,this is an Indication that you are running your car temperature below the optimum specified temperature .
You must be running your fan direct or thermostat removed or both which can spell doom for your engine cos of lubrication issue .
Running rich is even the least of the issue now but wear and tear in your engine in the long run .

autologic:

I guess your car is Honda ,this is an Indication that you are running your car temperature below the optimum specified temperature .
You must be running your fan direct or thermostat removed or both which can spell doom for your engine cos of lubrication issue .
Running rich is even the least of the issue now but wear and tear in your engine in the long run .

Oh yea.. It's a Honda accord 2005 v4..no thermostat and fan runs direct always.. Will need to fix it to remedy the running rich situation.. A quick one please.. Honda accord 2005 uses temperature sensor ryt? That's ect? I need to know more about it. So I will be properly guided as there is dearth of qualified auto gurus here in ph. Thanks

autologic:

I guess your car is Honda ,this is an Indication that you are running your car temperature below the optimum specified temperature .
You must be running your fan direct or thermostat removed or both which can spell doom for your engine cos of lubrication issue .
Running rich is even the least of the issue now but wear and tear in your engine in the long run .

autologic..it has happened.. My honda popped up a code.. P0172..system too rich.. What's the Way out sir.. Thanks..

captainking:
does removing thermostat cause the car to run rich?? With high negative long term trims??

Yes.