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Thread: dustin's duster injector flow test :(

  1. #1
    Owner AutoMods's Avatar
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    Thumbs up dustin's duster injector flow test :(

    Tested Dustin's 4g63 truck injectors today. He's been having some tuning issues. Found that injector 4 flowed about 20% more than the others in a lot of the tests. Not good. Sometimes debris can not allow the injector to fully close but I cleaned/flushed them and installed new filters and it did not fix the problem. The cleaning did fix injector 3 from leaking.

    Even though I couldn't fix the one, its still nice to find problems so you can replace it and move on vs trying to tune something that is broken.

    Here is a picture of the dynamic test with varying pulse widths and rpm's result. Injector 3 is a bit high but probably acceptable for a lot of people, injector 4 is just too much. Flowing 24% more than injector 2 in this test.
    dustin_720cc_injectors.jpg
    Last edited by AutoMods; 09-26-2012 at 08:17 PM.
    9.875@150mph
    2012 Iowa Manual Shootout Champion, on low boost setting. -Flying Ryan
    "The bitterness of poor quality remains long after the sweetness of low price is forgotten." - Ben Franklin

  2. #2
    Senior Member 85XR7Project's Avatar
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    That pretty cool! Now I can see why you wanted that.
    Brett
    '08 Dodge Caliber SRT4--Diablosport tune, MPx muffler, K&N drop in, Custom downpipe, Custom torque bars, Bwoody check valve, TurboXS 50 mm RFL Type H BOV. Running 19 psi.
    '67 Checker Marathon A-12E--283 V8, Powerglide (Classy ass cruiser)

  3. #3
    Senior Member oVa-Boost's Avatar
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    thats pretty cool all them years of 32psi n race gas killed them lol jk sucks there no good
    01' Trans am 3.8l v6
    02' red ws6
    08' trailblazer SS awd stock 13.9
    11' buick la crosse

  4. #4
    IAF Team Member
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    Lots of issues just kept pointing back with something related to fuel. I'm glad he got them over to you to test! Narrows down a lot of things.

  5. #5
    Owner AutoMods's Avatar
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    Definitely not ideal, but if all else was perfect with his truck, I wouldn't be surprised if it still ran "OK", maybe not but I wouldn't be surprised . The wideband will show rich but not extremely rich because the value is an average of 4 cylinders.

    For simplicity sake, lets say all injectors matched perfectly in the test above except injector 4 flowing 20% over the others. And our goal was to get an average of 100ml on all 4 injectors.

    1. 100ml 2. 100ml 3. 100ml 4. 120ml = an average of 105ml
    Since the wideband is after the merger of all 4 cylinders, we only know the average 105ml # . The wideband would show 5% richer than our goal.

    So to get down the 105ml to an average of 100ml you would pull fuel back 5% accross the board.

    That would leave our test at
    1. 95ml 2. 95ml 3. 95ml 4. 114ml

    So cylinders 1,2,3 would only be 5% leaner than our goal and bank #4 would be at 14% richer. And at that point the tuner would stop and give himself a pat on the back for doing a good job not knowing 3 cylinders are 5% lean and 4 is 14% rich

    I'm just thinking out loud and obviously we would be working with afr's not ml but hopefully that makes sense. Reading spark plugs or a wideband on each cylinder would also reveal the problem.
    Last edited by AutoMods; 09-27-2012 at 01:32 PM.
    9.875@150mph
    2012 Iowa Manual Shootout Champion, on low boost setting. -Flying Ryan
    "The bitterness of poor quality remains long after the sweetness of low price is forgotten." - Ben Franklin

  6. #6
    Moderator DustinsDuster's Avatar
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    yeah; kindof a shitty deal, but its the risk you take buying used stuff. im sure it didnt help they sat dry for two years as well.

    at the moment the plan is to throw Trevor's old stock Evo injectors in and see if i can get it running decently. anyone want to buy four 720cc injectors cheap? three of them match pretty decent!
    Tango 'til they're sore

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