Results 1 to 7 of 7

Thread: fuel trims problem

  1. #1
    Join Date
    May 2011
    Posts
    13

    fuel trims problem

    Dear friends hello.Sorry about my English, im from Greece and i can't whrite perfect!
    Somebody knows about fuel trims?Because i have some problem and i can't understand whats going on in my car!
    I have an hho system and works perfect with 1,5lpm at 1400cc engine
    I install an EFIE electronic with 2 o2 sensors and maf.
    I install it correct and a have lean out all sensors in maximum position as the manual say.
    I check all sensors with voltmeter and works good and in close loop condition
    After all i take a scantool and check all parameters from ecu on obd2 port.
    And the long fuel trim was +10!! The ecu reads lean and increase more fuel???
    We calibrate the o2 to read rich no lean!What's going on there!
    After all instalation take for a ride to test the gains and result.
    My car accelerate more powerfull,a lot of torque increase,and fuel economy was great! 30% economy than before!
    I have make a lot of changes in efie with different configurations and the Fuel trims always goes to + condition!Never see - at all.What's going on.Somebody knows about trims or ecu tuning?
    Thanks a lot!
    HYDROGEN POWER

  2. #2
    Join Date
    May 2011
    Posts
    13
    I have to inform you with some results.
    First i calibrate the 02 sensor 200mv up and the second 200mv up and map sensor in stock mode.
    My long fuel trim was 11 at medium speed and 9 at idle.
    After reset the trims(battery out) and test my car in stock mode without hho and efie.
    The results are long fuel trim 7 at all(idle-medium speed)
    After reset the trims again and install the efie again and the hho system.
    I calibrate the efie, first 02sensor at 250mv the second 200mv and maf down 30mv.
    When i start the engine the short fuel trim was +10-12 and the long 0 because i have reset it.
    After few minuits i put the maf at 10mv down and the first o2 at 300mv(this is the higher point,after that point the sensor stop function and stay at steady volts).
    The sort fuel trims after that drops to 0 and goes -1and+1 and the long fuel trims stay at 0.
    After that take the car for road test.
    My car power has the same power of acceleration,ignition time is good,temperatures are good,at 60mph and 3500rpm my long fuel trim goes to 3 and when i stop goes again to 0.
    Somebody knows whats going on with my fuel system?I think after so sensors enrichment(+300mv) the long fuel trims must be in - mode at all.
    I can't understand the result of economy.For this condition i must be have bad fuel economy and i have verry good economy.+30% economy of fuel!I'm going crazy!
    My car is opel corsa 1,4 16v 2003 mod with maf sensor. delphi ecu.
    Thanks
    HYDROGEN POWER

  3. #3
    Join Date
    May 2011
    Posts
    13
    I think the problem maybe is dirty fuel injectors!
    Or some problem in fuel system delivery.
    What do you think?
    HYDROGEN POWER

  4. #4
    Join Date
    May 2011
    Posts
    13
    Hey guys where are you?
    Some answere?
    You don't have some idea?
    HYDROGEN POWER

  5. #5
    Join Date
    May 2011
    Posts
    13
    ! hey guys hello!!
    HYDROGEN POWER

  6. #6
    Join Date
    Nov 2009
    Posts
    1,418
    Hellooooooooooooo. Your problem is taking some time to research and consider. So be patient. If this was a normal problem that many have experienced before the answer would be there in a minute. This is not the case so some research is in order. That takes time which some of us do not have a lot of.

    One thing is that with the use of the EFIE what you read from the OBD port might be distorted because of the EFIE. I know this to be a fact in some cases. I am not sure if it effects the long and short term trims and do not think it does. Research is needed to be sure. When one of the vehicles with an EFIE visits me I will check it but this will take time because I have no vehicles with EFIE's in California where they are illegal. One will have to come from another state which happens only every so often.
    "Democracy is two wolves and a lamb deciding what to have for dinner. Liberty is a well-armed lamb."

    ONE Liter per minute per 10 amps which just isn't possible Ha Ha .

  7. #7
    Join Date
    Feb 2012
    Location
    Fairview Heights, Illinois
    Posts
    12




    (two examples)

    This shows a table or map of your load cells, or otherwise known as fuel-trim cells.
    Down the side you see engine speed -RPM.
    Across the top you see the calculated load variable - Load.

    The load is determined primarily using the output of the MAF and/or MAP sensors, and then adjusted from there according to a few other sensor outputs and status conditions.

    As you go from idle to increased RPM or increased load as you drive, your PCM moves through the different cells of this table. That's why you see different LTFT values as your RPM or load changes. Each load/RPM cell has its own value that has been determined by the PCM via the adaptive fueling routine, that uses input from your main (Pre-CAT) O2 sensor.
    Don't confuse the movement through different load/RPM cells with your fuel trims changing. You have to compare a given cell for before and after values, so you either have to know the cell number you are in (they are assigned a number position value in the PCM), or reproduce the conditions (RPM & load) in order to display that cell on your scan-tool or scangauge. For instance the idle cell is easy to reproduce. It just takes a few minutes for the LTFT to update to a new value.
    Some scan-tools will allow you to clear the fuel trims by pushing a button, thus speeding up the LTFT update.

    Your EFIE would be altering the output of this O2 sensor if it were working properly, and over a short period of time ( a few miles of driving ) the PCM would re-calculate new values to store in these load/RPM cells, and you would see different fuel trims.

    Increasing the O2 voltage level will result in lower fuel trim values.
    If you do not see this, then either your EFIE isn't installed or working properly, or your scan-tool is not reporting your fuel trims properly.
    Your EFIE does need to be compatible with your O2 sensor type in order to function properly.
    If you feel your EFIE is working as it should based on feel, then I suggest using a different scan-tool to verify your fuel trim values.

    I hope this was helpful.

    I am also Greek by the way, and I do not know Greek language. How about that? I am good at English though.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •