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Thread: Mechanical Issues that prevent Good Tuning

  1. #1
    R.I.P Shawn, 1956-2011 WeathermanShawn's Avatar
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    Default Mechanical Issues that prevent Good Tuning

    In-Memory-of-Shawn-Sankey


    TUNERS CHECKLIST


    1. General Checklist
    On a cold start, just prior to starting, IAT and ECT should be very close, within a few degrees of each other
    MAP should read same as barometric pressure
    MAF should read zero airflow
    Battery should be fully charged and functional

    2. General Maintenance

    Replace air and fuel filters annually
    Check oil level and replace dirty oil
    Clean MAF with approved electrical cleaner
    Check PVC system
    Ensure spark plugs and wires are operating normally
    Check for manifold and exhaust leaks
    Replace Narrowband O2 sensors at least every 60,000 miles

    3. Injector Tuning

    Ensure your injector data is accurate
    Check fuel pressure and replace the fuel pump/wiring, if necessary
    Ensure you have the correct IFR slope (sloped vs. flat) and that it matches the FPR (un-reference vs. referenced)
    Check for fuel leaks anywhere, which this is a fire hazard
    Any bad grounds, insufficient wire sizing, and/or poor connections will lead to fueling problems

    4. Tuning/Mechanical Issues

    Ensure you do not have excessive heat-soak. For more accurate readings and consistent fueling, IAT Sensor should be located away from heat sources (like the radiator or the engine itself)
    Home-ported throttle body can be problematic
    Ensure catalytic converter(s) is(are) not blocked or plugged

    5. MAF & Other Sensors

    Good NBO2 in closed loop (i.e. trimming properly) will show these characteristics during steady part throttle:
    Swinging faster than two (2) complete cycles per second
    Swinging above 600 mV and below 300 mV
    Average voltage will be close to 450 mV
    If they switch slower than three (3) cycles per second, the trimming will lag a little behind
    If they switch without going above 600 mV or below 300 mV then a DTC will trigger
    If the average mV deviates significantly from 450 mV then the trimming will be to some unpredictable AFR
    MAF signal should not show jagged edges or rapid changes in airflow during cruise or WOT. Some oscillation is normal, but it should not exceed 5% per frame (1/10 sec)
    Wideband Location is crucial. Tailpipe locations should be avoided. Follow the wideband manufacturer’s guidance as to the location and installation. Sensors should be calibrated regularly, including heater calibrations if necessary.


    Example of normal operating Closed-loop Scan with Fresh O2 Sensors. (Long-Tube Header Location) Shows NB switching, steady MAF signal, and wideband oscillating normally around stoich AFR.




    Example of why you should NEVER use Stock NarrowBands for WOT Tuning
    Fresh NB O2's..AFR both 12.62.

    1. IAT 90F MV: 872-890



    2. IAT 64F MV: 929-942



    Attached Files Attached Files
    Last edited by joecar; July 18th, 2011 at 09:39 AM.
    2002 Black Camaro Z-28 M6 Hardtop 11.0:1CR 425HP/410TQ SAE (400TQ@3500RPM)
    200cc Heads, 228/232 110+2 Cam, 1 3/4" LT's w/catts, GMMG, Koni Shocks, Hotchkis Springs, 35/21 Sways, 17" ZR1's, 3.90 Gears Roadrunner PCM LM-2 Serial Wideband
    EFILive Closed-Loop MAF/SD Hybrid Tune..


  2. #2
    Lifetime Member 5.7ute's Avatar
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    Good idea for a thread Shawn.
    An issue I have come across a fair bit is due to insufficient fuel pressure at the rail, especially on older cars. It has become that common that I always log fuel pressure when dialling in a car these days.
    The Tremor at AIR

  3. #3
    R.I.P Shawn, 1956-2011 WeathermanShawn's Avatar
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    Thanks Mick.

    Good one. We will add it to our list.
    2002 Black Camaro Z-28 M6 Hardtop 11.0:1CR 425HP/410TQ SAE (400TQ@3500RPM)
    200cc Heads, 228/232 110+2 Cam, 1 3/4" LT's w/catts, GMMG, Koni Shocks, Hotchkis Springs, 35/21 Sways, 17" ZR1's, 3.90 Gears Roadrunner PCM LM-2 Serial Wideband
    EFILive Closed-Loop MAF/SD Hybrid Tune..


  4. #4
    Lifetime Member ChipsByAl's Avatar
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    Its not exactly a mechanical issue, but not having accurate injector information can be a problem also. The transmission\clutch needs to be in good condition before any WOT tuning. The vehicle being due for an oil change or even low on oil can abruptly stop the tuning process. Just some things that need to be checked before starting.
    Al
    "Trash that carb and get Injected!"

  5. #5
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    Good one Shawn,
    I have always had mid rage knock after playing with tining and fuel presure so on so forth, found its valve train noise.
    Jorge

  6. #6
    R.I.P Shawn, 1956-2011 WeathermanShawn's Avatar
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    Thanks Al and Jorge.

    All very good examples that we can use.
    Appreciate the ideas..
    2002 Black Camaro Z-28 M6 Hardtop 11.0:1CR 425HP/410TQ SAE (400TQ@3500RPM)
    200cc Heads, 228/232 110+2 Cam, 1 3/4" LT's w/catts, GMMG, Koni Shocks, Hotchkis Springs, 35/21 Sways, 17" ZR1's, 3.90 Gears Roadrunner PCM LM-2 Serial Wideband
    EFILive Closed-Loop MAF/SD Hybrid Tune..


  7. #7
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    I agree with Chips - having the correct size injectors is key. Also I found a big difference in my tune after I cleaned the K & N intake filter. I was shocked (and slightly embarrassed) how dirty it was and what a difference it made in VE tables and idle quality.

  8. #8
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    i am new to the tuning end of it but what i have found out working on cars is if the map shows bad or is giving trouble change the relay in its line first . 2 fuel pressure problems or running lean change the fuel filter
    donald

  9. #9
    Joe (Moderator) joecar's Avatar
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    Air and fuel filters are a periodic maintenance item, they should be changed/cleaned at least once a year.

    Many people ignore the fuel filter (out of sight, out of mind).

    Small things like dirty filters, dirty MAF, leaky PCV plumbing can really frustrate a tuner... when you see no convergence then you know something is up.

  10. #10
    Joe (Moderator) joecar's Avatar
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    Another problem is having the wrong IFR slope (sloped vs flat) that does not match the FPR (un-reference vs referenced).

    Also, fuel pressure should be checked, and the fuel pump diagnosed if necessary.

    And, there should be absolutely no fuel leaks anywhere, which this is a fire hazard.

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