Long Term / Short Term Fuel Trim

neto1978 · April 27, 2009

as I wrote before ,my truck is setting dtc P1175 and P0304 all the time.

with my actron scanner ,I checked the freeze frame data and:

the long term and short term fuel trim 3&4 are 32.8%

what that means?

is that true:

The purpose of the fuel trims is to compensate for varying injector flow over the life of the car. So if your injectors are slowly clogging, the stock ECU will use the fuel trim to compensate by turning on the injectors for a slightly longer time.

so is it a case of injectors getting clogged?

tks

svensk · April 27, 2009

Have you taken it to the dealer yet?

superjim · April 27, 2009

This is puzzling to me why you are even working on it.

It is a 2008 model.

It is still under warranty, or at least I assume it is.

Why are you even messing with it?

The dealer gets paid to fix your problems.

Let them earn their money.

Bostonsfavson · April 27, 2009

This is puzzling to me why you are even working on it.
It is a 2008 model.

It is still under warranty, or at least I assume it is.

Why are you even messing with it?

The dealer gets paid to fix your problems.

Let them earn their money.

+70987089566458

neto1978 · April 27, 2009

I LIVE IN BRAZIL <THERE"S NO WARRANTY FOR THIS VEHICLE DOWN HERE!!!

I IMPORTED IT BY MYSELF!!!

NOW IF ANYBODY CAN HELP ME...

This is puzzling to me why you are even working on it.
It is a 2008 model.

It is still under warranty, or at least I assume it is.

Why are you even messing with it?

The dealer gets paid to fix your problems.

Let them earn their money.

jrrod2004 · April 27, 2009

Hey Luiz:

Fuel System - Driveability Issues/MIL ON/DTC's Set

Bulletin No.: 03-06-04-030E

Date: June 12, 2007

TECHNICAL

Subject:

Various Driveability Symptoms Due to Clogged Fuel Injectors, MIL/SES DTCs P0171, P0172, P0174, P0300, P1174, P1175 (Clean Fuel Injectors and/or Perform Injector Test With AFIT - CH-47976)

Models

Supercede:

This bulletin is being revised to update the service information in step number 3 under Injector Cleaning Procedure and update the Warranty Information (excluding Saab U.S. Models). Please discard Corporate Bulletin Number 03-06-04-030D (Section 06 - Engine/Propulsion System).

Condition

Some customers may comment on any of the following various driveability symptoms:

Extended Crank Time

Hard to Start

MIL/SES Illuminated with DTCs

Hesitation

Lack of Power

Surge or Chuggle

Rough Idle

Light or Intermittent Misfire

Cause

Due to various factors, the fuel injectors may become restricted. Extensive testing has demonstrated that fuel related issues are the cause of clogged injectors. At this point, no specific fuel, fuel constituent, or engine condition has been identified as causing the restriction. The restriction causes the engine to operate at a lean air fuel ratio. This may either trigger the MIL to illuminate or the engine to develop various driveability symptoms.

Correction

Fuel injector restrictions, deposits can be cleaned on the vehicle using the following procedure. Under NO circumstances should this procedure be modified, changed or shortened. As a long term solution, and to prevent reoccurrence, customers should be encouraged to use Top Tier Detergent Gasoline. For further information on Top Tier detergent gasoline and fuel retailers, please refer to the following Corporate Bulletin Numbers:

04-06-04-047G (U.S. Only)

05-06-04-022C (Canada ONLY)

GM UPPER ENGINE AND FUEL INJECTOR CLEANER is the only injector cleaning agent approved for use with General Motors fuel system components. Other injector cleaners may cause damage to plastics, plated metals or bearings. General Motors has completed extensive laboratory testing of GM Upper Engine and Fuel Injector Cleaner, and can assure its compatibility with General Motors fuel system components, as long as the cleaning procedure is followed correctly.

The following tools, or their equivalent, are required:

CH-47976 Active Fuel Injector Tester (AFIT)

J 35800-A Fuel Injector Cleaner

J 37287 Fuel Line Shut-off Adapter

J 42964 Fuel Line Shut-off Adapter

J 42873 Fuel Line Shut-off Adapter

* One bottle of GM Upper Engine and Fuel Injector Cleaner, P/N 88861802 (in Canada, P/N 88861804)

* One bottle of GM Fuel System Treatment Plus, P/N 88861011 (in Canada, P/N 88861012)

Some dealers may not have an Active Fuel Injector Tester (AFIT - CH-47976). Dealers can contact 1-800-GM-TOOLS (1-800-468-6657) to order an AFIT - CH-47976. Dealers still can test the fuel injectors without an AFIT. Refer to Fuel Injector Diagnosis (W/ J 39021 or Tech 2®) in SI.

As mentioned in the AFIT User Guide, vehicles that are not listed in the AFIT menu can still be tested with the AFIT. Depending on the model, it may be possible to enter the previous model year and proceed with testing using the DLC connection. If this is not possible on the model that you are working on, it will be necessary to use the direct connection method outlined in the AFIT User Guide (See Pages 17-31).

General Motors recommends that the Active Fuel Injector Tester (AFIT) be used in testing fuel injectors. If the SI diagnostics do not isolate a cause for this concern, use the Active Fuel Injector Tester (AFIT - CH-47976) to perform an Injector Test as outlined in the AFIT User Guide.

The AFIT Injector Test measures the flow characteristics of all fuel injectors, which is more precise when compared with the standard Tech 2® fuel injector balance test. As a result, the AFIT is more likely to isolate the cause of a P1174 DTC (for example: if it is being caused by a fuel injector concern).

The CH-47976 (Active Fuel Injector Tester - AFIT) can also be used to measure fuel pressure and fuel system leak down. Also, as mentioned in the P1174 SI diagnosis, if the misfire current counters or misfire graph indicate any misfires, it may be an indicator of the cylinder that is causing the concern. Refer to Fuel Injector Diagnosis (w/CH-47976) in SI for additional instructions.

To access the training video on AFIT, take the following path at the GM Training Website:

After logging into the gmtraining.com website, choose the link on the left side of the page titled web video library.

Then choose "technical".

Next, within the search box, type in September course number 10206.09D.

This will bring up a link with this course. Scroll through to choose feature topic."

At this point, the seminar can be chosen to view or the video related to the AFIT.

Additional training is available from the gmtraining.com website. Please see TECHassist 16044.18T2 Active Fuel Injector Tester and also see 16043.51D Engine Mechanical Diagnosis & Measurement for more information on GM Upper Engine and Fuel Injector Cleaner.

Also, dealers can now download software updates for the AFIT at GM Dealer Equipment (GMDE) on the web at http://www.gmde.net/AFIT.cfm..

To access the training video on AFIT, take the following path at the GMPro LMS Training Website:

After logging into the website, choose the link on the left side of the page titled "Catalog."

Then choose "Catalog Search."

Next, within the search box, Select Course Number - Contains - "T" then select search.

This will bring up a list of TECHassist courses. Scroll through to choose "Active Fuel Injector Tester" and select "View."

At this point, a new window will open and the program can be Launched.

Also, dealers can now download software updates for the AFIT at GM Dealer Equipment (GMDE) on the web at http://www.gmde.net/softwareupdates/.

Additional information can be found on AFIT (June 2006 Edition) and GM Upper Engine and Fuel Injector Cleaner (November 2006 Edition) in Techlink. To access the articles, take the following path:

Go to GM DealerWorld (U.S.) or the GM infoNET (Canada).

Click on the Service Tab in DealerWorld (GM infoNET for Canada).

Click on the GM Techlink Hyperlink.

Click on the Archives Hyperlink at GM Techlink.

Click on 06-2006 in the Archives Section and Click on the Active Fuel Injector Tester Link in the June 2006 Techlink Article.

Click on 11-2006 in the Archives Section and Click on the GM Top Engine Cleaner Replaced Link in the November 2006 Techlink Article.

GM UPPER ENGINE AND FUEL INJECTOR CLEANER is the only injector cleaning agent recommended. DO NOT USE OTHER CLEANING AGENTS AS THEY MAY CONTAIN METHANOL, WHICH CAN DAMAGE FUEL SYSTEM COMPONENTS. Under NO circumstances should the GM Upper Engine and Fuel Injector Cleaner be added to the vehicle fuel tank.

Do not exceed the recommended cleaning solution concentration. Testing has demonstrated that exceeding the recommended cleaning solution concentration does not improve the effectiveness of this procedure.

Vehicles with less than 160 km (100 mi) on the odometer should not have the injectors cleaned. These vehicles should have any out of specification injectors replaced.

For 4, 5 and 6 cylinder engines, empty two of the 30 ml (1 oz) reservoirs of the GM Upper Engine and Fuel Injector Cleaner container into the J 35800-A - Injector Cleaning Tank then add 420 ml (14 oz) of regular unleaded gasoline. If you are using any other brand of cleaning tank, you will need a total of 60 ml (2 oz) mixed with 420 ml (14 oz) of regular unleaded gasoline.

For 8 cylinder engines, empty two of the 30 ml (1 oz) reservoirs of the GM Upper Engine and Fuel Injector Cleaner container into the J 35800-A - Injector Cleaning Tank then add 420 ml (14 oz) of regular unleaded gasoline. If you are using any other brand of cleaning tank, you will need a total of 60 ml (2 oz) of Upper Engine and Fuel Injector Cleaner mixed with 420 ml (14 oz) of regular unleaded gasoline. This procedure will need to be repeated for a second time for an 8 cylinder engine (8 cylinder engines receive 960 ml total fluid - 120 ml (4 oz) of Upper Engine and Fuel Injector Cleaner and 840 ml (28 oz) of gasoline.

Be sure to follow all additional instructions provided with the tool.

Electrically disable the vehicle fuel pump by removing the fuel pump relay and disconnecting the oil pressure switch connector, if equipped.

Turn the ignition to the OFF position.

Relieve fuel pressure and disconnect the fuel feed and return lines at the fuel rail. Plug the fuel feed and return lines coming off the fuel rail with J 37287, J 42873 or J 42964 as appropriate for the fuel system.

Connect the J 35800-A to the vehicle fuel rail.

Pressurize the J 35800-A to 510 kPa (75 psi).

Start and idle the engine until it stalls, due to lack of fuel. This should take approximately 15-20 minutes.

Turn the ignition to the OFF position.

Disconnect the J 35800-A from the fuel rail.

Reconnect the vehicle fuel pump relay and oil pressure switch connector, if equipped.

Remove the J 37287, J 42873 or J 42964 and reconnect the vehicle fuel feed and return lines.

Start and idle the vehicle for an additional two minutes to ensure residual injector cleaner is flushed from the fuel rail and fuel lines.

Pour the entire contents of GM Fuel System Treatment Plus (P/N 88861011 [in Canada, P/N 88861012]) into the tank and advise the customer to fill the tank.

Review the benefits of using Top Tier Detergent gasoline with the customer and recommend that they add a bottle of GM Fuel System Treatment Plus to the fuel tank at every oil change. Regular use of GM Fuel System Treatment Plus should keep the customer from having to repeat the injector cleaning procedure. Road test the vehicle to verify that the customer concern has been corrected.

Parts Information

Warranty Information (excluding Saab U.S. Models)

For vehicles repaired under warranty, use the table.

Warranty Information (Saab U.S. Models)

For vehicles repaired under warranty, use the table.

Injector Worksheet (Use with Tech2® Balance Test)

Disclaimer

That was obtained for one of the older vehicles. I would say that the type of fuel that you are using may not be up to specs and you may have to run a cleaner once every oil change.

Error Code: P0304 relates to a misfire that was detected. That misfire may be the result of the clogged injector.

My diagnosis: Run some type of approved fuel cleaner and see if there are any alternate sources of fuel available. Also try the GM Top Engine Cleaner (or similar). Hope this helps.

neto1978 · April 27, 2009

it helpEd me a lot cueva !!!

thank you very much!!!

I will try using a cleaner on the tank first ...

best regards.

luiz.

Hey Luiz:

Fuel System - Driveability Issues/MIL ON/DTC's Set

Bulletin No.: 03-06-04-030E

Date: June 12, 2007

TECHNICAL

Subject:

Various Driveability Symptoms Due to Clogged Fuel Injectors, MIL/SES DTCs P0171, P0172, P0174, P0300, P1174, P1175 (Clean Fuel Injectors and/or Perform Injector Test With AFIT - CH-47976)

Models

Supercede:

This bulletin is being revised to update the service information in step number 3 under Injector Cleaning Procedure and update the Warranty Information (excluding Saab U.S. Models). Please discard Corporate Bulletin Number 03-06-04-030D (Section 06 - Engine/Propulsion System).

Condition

Some customers may comment on any of the following various driveability symptoms:

Extended Crank Time

Hard to Start

MIL/SES Illuminated with DTCs

Hesitation

Lack of Power

Surge or Chuggle

Rough Idle

Light or Intermittent Misfire

Cause

Due to various factors, the fuel injectors may become restricted. Extensive testing has demonstrated that fuel related issues are the cause of clogged injectors. At this point, no specific fuel, fuel constituent, or engine condition has been identified as causing the restriction. The restriction causes the engine to operate at a lean air fuel ratio. This may either trigger the MIL to illuminate or the engine to develop various driveability symptoms.

Correction

Fuel injector restrictions, deposits can be cleaned on the vehicle using the following procedure. Under NO circumstances should this procedure be modified, changed or shortened. As a long term solution, and to prevent reoccurrence, customers should be encouraged to use Top Tier Detergent Gasoline. For further information on Top Tier detergent gasoline and fuel retailers, please refer to the following Corporate Bulletin Numbers:

04-06-04-047G (U.S. Only)

05-06-04-022C (Canada ONLY)

GM UPPER ENGINE AND FUEL INJECTOR CLEANER is the only injector cleaning agent approved for use with General Motors fuel system components. Other injector cleaners may cause damage to plastics, plated metals or bearings. General Motors has completed extensive laboratory testing of GM Upper Engine and Fuel Injector Cleaner, and can assure its compatibility with General Motors fuel system components, as long as the cleaning procedure is followed correctly.

The following tools, or their equivalent, are required:

CH-47976 Active Fuel Injector Tester (AFIT)

J 35800-A Fuel Injector Cleaner

J 37287 Fuel Line Shut-off Adapter

J 42964 Fuel Line Shut-off Adapter

J 42873 Fuel Line Shut-off Adapter

* One bottle of GM Upper Engine and Fuel Injector Cleaner, P/N 88861802 (in Canada, P/N 88861804)

* One bottle of GM Fuel System Treatment Plus, P/N 88861011 (in Canada, P/N 88861012)

Some dealers may not have an Active Fuel Injector Tester (AFIT - CH-47976). Dealers can contact 1-800-GM-TOOLS (1-800-468-6657) to order an AFIT - CH-47976. Dealers still can test the fuel injectors without an AFIT. Refer to Fuel Injector Diagnosis (W/ J 39021 or Tech 2®) in SI.

As mentioned in the AFIT User Guide, vehicles that are not listed in the AFIT menu can still be tested with the AFIT. Depending on the model, it may be possible to enter the previous model year and proceed with testing using the DLC connection. If this is not possible on the model that you are working on, it will be necessary to use the direct connection method outlined in the AFIT User Guide (See Pages 17-31).

General Motors recommends that the Active Fuel Injector Tester (AFIT) be used in testing fuel injectors. If the SI diagnostics do not isolate a cause for this concern, use the Active Fuel Injector Tester (AFIT - CH-47976) to perform an Injector Test as outlined in the AFIT User Guide.

The AFIT Injector Test measures the flow characteristics of all fuel injectors, which is more precise when compared with the standard Tech 2® fuel injector balance test. As a result, the AFIT is more likely to isolate the cause of a P1174 DTC (for example: if it is being caused by a fuel injector concern).

The CH-47976 (Active Fuel Injector Tester - AFIT) can also be used to measure fuel pressure and fuel system leak down. Also, as mentioned in the P1174 SI diagnosis, if the misfire current counters or misfire graph indicate any misfires, it may be an indicator of the cylinder that is causing the concern. Refer to Fuel Injector Diagnosis (w/CH-47976) in SI for additional instructions.

To access the training video on AFIT, take the following path at the GM Training Website:

After logging into the gmtraining.com website, choose the link on the left side of the page titled web video library.

Then choose "technical".

Next, within the search box, type in September course number 10206.09D.

This will bring up a link with this course. Scroll through to choose feature topic."

At this point, the seminar can be chosen to view or the video related to the AFIT.

Additional training is available from the gmtraining.com website. Please see TECHassist 16044.18T2 Active Fuel Injector Tester and also see 16043.51D Engine Mechanical Diagnosis & Measurement for more information on GM Upper Engine and Fuel Injector Cleaner.

Also, dealers can now download software updates for the AFIT at GM Dealer Equipment (GMDE) on the web at http://www.gmde.net/AFIT.cfm..

To access the training video on AFIT, take the following path at the GMPro LMS Training Website:

After logging into the website, choose the link on the left side of the page titled "Catalog."

Then choose "Catalog Search."

Next, within the search box, Select Course Number - Contains - "T" then select search.

This will bring up a list of TECHassist courses. Scroll through to choose "Active Fuel Injector Tester" and select "View."

At this point, a new window will open and the program can be Launched.

Also, dealers can now download software updates for the AFIT at GM Dealer Equipment (GMDE) on the web at http://www.gmde.net/softwareupdates/.

Additional information can be found on AFIT (June 2006 Edition) and GM Upper Engine and Fuel Injector Cleaner (November 2006 Edition) in Techlink. To access the articles, take the following path:

Go to GM DealerWorld (U.S.) or the GM infoNET (Canada).

Click on the Service Tab in DealerWorld (GM infoNET for Canada).

Click on the GM Techlink Hyperlink.

Click on the Archives Hyperlink at GM Techlink.

Click on 06-2006 in the Archives Section and Click on the Active Fuel Injector Tester Link in the June 2006 Techlink Article.

Click on 11-2006 in the Archives Section and Click on the GM Top Engine Cleaner Replaced Link in the November 2006 Techlink Article.

GM UPPER ENGINE AND FUEL INJECTOR CLEANER is the only injector cleaning agent recommended. DO NOT USE OTHER CLEANING AGENTS AS THEY MAY CONTAIN METHANOL, WHICH CAN DAMAGE FUEL SYSTEM COMPONENTS. Under NO circumstances should the GM Upper Engine and Fuel Injector Cleaner be added to the vehicle fuel tank.

Do not exceed the recommended cleaning solution concentration. Testing has demonstrated that exceeding the recommended cleaning solution concentration does not improve the effectiveness of this procedure.

Vehicles with less than 160 km (100 mi) on the odometer should not have the injectors cleaned. These vehicles should have any out of specification injectors replaced.

For 4, 5 and 6 cylinder engines, empty two of the 30 ml (1 oz) reservoirs of the GM Upper Engine and Fuel Injector Cleaner container into the J 35800-A - Injector Cleaning Tank then add 420 ml (14 oz) of regular unleaded gasoline. If you are using any other brand of cleaning tank, you will need a total of 60 ml (2 oz) mixed with 420 ml (14 oz) of regular unleaded gasoline.

For 8 cylinder engines, empty two of the 30 ml (1 oz) reservoirs of the GM Upper Engine and Fuel Injector Cleaner container into the J 35800-A - Injector Cleaning Tank then add 420 ml (14 oz) of regular unleaded gasoline. If you are using any other brand of cleaning tank, you will need a total of 60 ml (2 oz) of Upper Engine and Fuel Injector Cleaner mixed with 420 ml (14 oz) of regular unleaded gasoline. This procedure will need to be repeated for a second time for an 8 cylinder engine (8 cylinder engines receive 960 ml total fluid - 120 ml (4 oz) of Upper Engine and Fuel Injector Cleaner and 840 ml (28 oz) of gasoline.

Be sure to follow all additional instructions provided with the tool.

Electrically disable the vehicle fuel pump by removing the fuel pump relay and disconnecting the oil pressure switch connector, if equipped.

Turn the ignition to the OFF position.

Relieve fuel pressure and disconnect the fuel feed and return lines at the fuel rail. Plug the fuel feed and return lines coming off the fuel rail with J 37287, J 42873 or J 42964 as appropriate for the fuel system.

Connect the J 35800-A to the vehicle fuel rail.

Pressurize the J 35800-A to 510 kPa (75 psi).

Start and idle the engine until it stalls, due to lack of fuel. This should take approximately 15-20 minutes.

Turn the ignition to the OFF position.

Disconnect the J 35800-A from the fuel rail.

Reconnect the vehicle fuel pump relay and oil pressure switch connector, if equipped.

Remove the J 37287, J 42873 or J 42964 and reconnect the vehicle fuel feed and return lines.

Start and idle the vehicle for an additional two minutes to ensure residual injector cleaner is flushed from the fuel rail and fuel lines.

Pour the entire contents of GM Fuel System Treatment Plus (P/N 88861011 [in Canada, P/N 88861012]) into the tank and advise the customer to fill the tank.

Review the benefits of using Top Tier Detergent gasoline with the customer and recommend that they add a bottle of GM Fuel System Treatment Plus to the fuel tank at every oil change. Regular use of GM Fuel System Treatment Plus should keep the customer from having to repeat the injector cleaning procedure. Road test the vehicle to verify that the customer concern has been corrected.

Parts Information

Warranty Information (excluding Saab U.S. Models)

For vehicles repaired under warranty, use the table.

Warranty Information (Saab U.S. Models)

For vehicles repaired under warranty, use the table.

Injector Worksheet (Use with Tech2® Balance Test)

Disclaimer

That was obtained for one of the older vehicles. I would say that the type of fuel that you are using may not be up to specs and you may have to run a cleaner once every oil change.

Error Code: P0304 relates to a misfire that was detected. That misfire may be the result of the clogged injector.

My diagnosis: Run some type of approved fuel cleaner and see if there are any alternate sources of fuel available. Also try the GM Top Engine Cleaner (or similar). Hope this helps.

Draenor · April 27, 2009

as I wrote before ,my truck is setting dtc P1175 and P0304 all the time.
with my actron scanner ,I checked the freeze frame data and:

the long term and short term fuel trim 3&4 are 32.8%

what that means?

is that true:

The purpose of the fuel trims is to compensate for varying injector flow over the life of the car. So if your injectors are slowly clogging, the stock ECU will use the fuel trim to compensate by turning on the injectors for a slightly longer time.

so is it a case of injectors getting clogged?

tks

Fuel trims are what the truck uses to calculate the fuel needed for proper operation. It starts out with both long and short fuel trims at zero from the factory. After the pcm calculates the amout of fuel needed, it injects a certain amount and then looks at the O2 sensor. If the O2 sensor tells the pcm that it didn't inject enough fuel(lean) the pcm adjusts the short term to compensate for the difference each injecton event until the )2 says it saw the right amount of fuel for what the pcm calculated.

jrrod2004 · April 27, 2009

as I wrote before ,my truck is setting dtc P1175 and P0304 all the time.
with my actron scanner ,I checked the freeze frame data and:

the long term and short term fuel trim 3&4 are 32.8%

what that means?

is that true:

The purpose of the fuel trims is to compensate for varying injector flow over the life of the car. So if your injectors are slowly clogging, the stock ECU will use the fuel trim to compensate by turning on the injectors for a slightly longer time.

so is it a case of injectors getting clogged?

tks

Fuel trims are what the truck uses to calculate the fuel needed for proper operation. It starts out with both long and short fuel trims at zero from the factory. After the pcm calculates the amout of fuel needed, it injects a certain amount and then looks at the O2 sensor. If the O2 sensor tells the pcm that it didn't inject enough fuel(lean) the pcm adjusts the short term to compensate for the difference each injecton event until the )2 says it saw the right amount of fuel for what the pcm calculated.

interesting. I didnt know how it operated. Thanks for the technical details.

fbachman · April 27, 2009

Just a shot in the dark.... are you running an aftermarket tune?

Do you have a "trick"/aftermarket MAF sensor?

Did you modify the intake? You running long-tube headers? Anything like that?

You're in Brazil.... whats the altitude where you are? If you are at high altitude, it is possible that the look-up table for AFR may be biased due to the alitiude, and a 30+% bias may be understandable.

Maybe an O2 sensor, or two, is/are on the fritz.

An LTFT as high as 30+% means that your ECM is trying to hit a target Air-Fuel Ratio, and it is requiring a 30+% "adjustment" on fuel flow to get there.

The cause of such an occurence can be plentiful, both due to a problem with the vehicle, OR the result of mods that specifically effect the air flow capacity (either in, or out of the engine).

EDIT: Oh yeah... one other thought. Brazilian Fuel. Does it contain Ethenol? If so, in what percentage. As the percent ethanol goes up, the stoichiometric AFR changes enough, and the O2 concentration in the exhasut changes enough to where that might be what's wacking things out.

Draenor · April 27, 2009

An LTFT as high as 30+% means that your ECM is trying to hit a target Air-Fuel Ratio, and it is requiring a 30+% "adjustment" on fuel flow to get there.

jrrod2004 · April 27, 2009

Just a shot in the dark.... are you running an aftermarket tune?

Do you have a "trick"/aftermarket MAF sensor?

Did you modify the intake? You running long-tube headers? Anything like that?

You're in Brazil.... whats the altitude where you are? If you are at high altitude, it is possible that the look-up table for AFR may be biased due to the alitiude, and a 30+% bias may be understandable.

Maybe an O2 sensor, or two, is/are on the fritz.

An LTFT as high as 30+% means that your ECM is trying to hit a target Air-Fuel Ratio, and it is requiring a 30+% "adjustment" on fuel flow to get there.

The cause of such an occurence can be plentiful, both due to a problem with the vehicle, OR the result of mods that specifically effect the air flow capacity (either in, or out of the engine).

EDIT: Oh yeah... one other thought. Brazilian Fuel. Does it contain Ethenol? If so, in what percentage. As the percent ethanol goes up, the stoichiometric AFR changes enough, and the O2 concentration in the exhasut changes enough to where that might be what's wacking things out.

I didnt know all of that could affect it.

neto1978 · April 27, 2009

my truck is flexfuel ,so there's no problem with ethanol...

I USE 15% pure gasoline,78% ethanol ,7% water.

I only use the hypertech maxenergy to raise the speed limit and transmission firmness ,all the rest is stock!

the truck stayed 6 months parked in the port ,maybe the injectors got clogged at that point...

what do you think?

tks

Just a shot in the dark.... are you running an aftermarket tune?

Do you have a "trick"/aftermarket MAF sensor?

Did you modify the intake? You running long-tube headers? Anything like that?

You're in Brazil.... whats the altitude where you are? If you are at high altitude, it is possible that the look-up table for AFR may be biased due to the alitiude, and a 30+% bias may be understandable.

Maybe an O2 sensor, or two, is/are on the fritz.

An LTFT as high as 30+% means that your ECM is trying to hit a target Air-Fuel Ratio, and it is requiring a 30+% "adjustment" on fuel flow to get there.

The cause of such an occurence can be plentiful, both due to a problem with the vehicle, OR the result of mods that specifically effect the air flow capacity (either in, or out of the engine).

EDIT: Oh yeah... one other thought. Brazilian Fuel. Does it contain Ethenol? If so, in what percentage. As the percent ethanol goes up, the stoichiometric AFR changes enough, and the O2 concentration in the exhasut changes enough to where that might be what's wacking things out.

jrrod2004 · April 27, 2009

my truck is flexfuel ,so there's no problem with ethanol...
I USE 15% pure gasoline,78% ethanol ,7% water.

I only use the hypertech maxenergy to raise the speed limit and transmission firmness ,all the rest is stock!

the truck stayed 6 months parked in the port ,maybe the injectors got clogged at that point...

what do you think?

tks

Just a shot in the dark.... are you running an aftermarket tune?

Do you have a "trick"/aftermarket MAF sensor?

Did you modify the intake? You running long-tube headers? Anything like that?

You're in Brazil.... whats the altitude where you are? If you are at high altitude, it is possible that the look-up table for AFR may be biased due to the alitiude, and a 30+% bias may be understandable.

Maybe an O2 sensor, or two, is/are on the fritz.

An LTFT as high as 30+% means that your ECM is trying to hit a target Air-Fuel Ratio, and it is requiring a 30+% "adjustment" on fuel flow to get there.

The cause of such an occurence can be plentiful, both due to a problem with the vehicle, OR the result of mods that specifically effect the air flow capacity (either in, or out of the engine).

EDIT: Oh yeah... one other thought. Brazilian Fuel. Does it contain Ethenol? If so, in what percentage. As the percent ethanol goes up, the stoichiometric AFR changes enough, and the O2 concentration in the exhasut changes enough to where that might be what's wacking things out.

yeah, I would never leave that ethanol in the tank for that long (not talking down on you or ragging you) but if I was to store a vehicle for 6 months, I would drain all fluids out of the vehicle and put them in the bed in their own separate containers. Depending on the method of storage, that stuff may just be old and you probably would have to burn it off. I would say that your truck is in for good cleaning, perhaps run it for several weeks with cleaning agents running through it. I think the injectors were fine until you ran it with that 6 month old stuff that was in the tank.

neto1978 · April 27, 2009

well ,the fuel in the tank was gasoline from USA ,I put myself in Miami,fl when I took it to the freight forwarder...

maybe even good gasoline over the time can clog the injectors...

tks cueva!

my truck is flexfuel ,so there's no problem with ethanol...
I USE 15% pure gasoline,78% ethanol ,7% water.

I only use the hypertech maxenergy to raise the speed limit and transmission firmness ,all the rest is stock!

the truck stayed 6 months parked in the port ,maybe the injectors got clogged at that point...

what do you think?

tks

Just a shot in the dark.... are you running an aftermarket tune?

Do you have a "trick"/aftermarket MAF sensor?

Did you modify the intake? You running long-tube headers? Anything like that?

You're in Brazil.... whats the altitude where you are? If you are at high altitude, it is possible that the look-up table for AFR may be biased due to the alitiude, and a 30+% bias may be understandable.

Maybe an O2 sensor, or two, is/are on the fritz.

An LTFT as high as 30+% means that your ECM is trying to hit a target Air-Fuel Ratio, and it is requiring a 30+% "adjustment" on fuel flow to get there.

The cause of such an occurence can be plentiful, both due to a problem with the vehicle, OR the result of mods that specifically effect the air flow capacity (either in, or out of the engine).

EDIT: Oh yeah... one other thought. Brazilian Fuel. Does it contain Ethenol? If so, in what percentage. As the percent ethanol goes up, the stoichiometric AFR changes enough, and the O2 concentration in the exhasut changes enough to where that might be what's wacking things out.

yeah, I would never leave that ethanol in the tank for that long (not talking down on you or ragging you) but if I was to store a vehicle for 6 months, I would drain all fluids out of the vehicle and put them in the bed in their own separate containers. Depending on the method of storage, that stuff may just be old and you probably would have to burn it off. I would say that your truck is in for good cleaning, perhaps run it for several weeks with cleaning agents running through it. I think the injectors were fine until you ran it with that 6 month old stuff that was in the tank.