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Thread: Injector Timing? Reference Periods? refereencing what?

  1. #601
    Senior Tuner kingtal0n's Avatar
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    Quote Originally Posted by anniversaryss View Post
    Ok so i went back and read about 17 pages.
    Looks likes we are changing our makeup table the same amount as we increase the normal.

    Also ive come to gather we are moving our injection timing to end as the exhaust valve close and not start?

    Assume it takes a little playing around but this is what ive come to understand.

    In an ecu where you can adjust the EOIT based on RPM its been said that injecting during peak piston velocity (intake stroke) is ideal for power situations (3k+ i guess)

    Whereas near idle speeds you do not want to spray into an open intake valve due to potential for cylinder washing.

    It depends on the fuel used, and temperature of the engine parts, i.e. high temperature engine parts + gasoline is going to vaporize very quickly (and not wash down the bore) But as the engine parts are colder or alternative fuels may be used (injecting far more alcohol which tends to cool parts as it evaporates) the late injections can become problematic not just with cylinder washing but with vaporization/atomization.

  2. #602
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    Quote Originally Posted by kingtal0n View Post
    In an ecu where you can adjust the EOIT based on RPM its been said that injecting during peak piston velocity (intake stroke) is ideal for power situations (3k+ i guess)

    Whereas near idle speeds you do not want to spray into an open intake valve due to potential for cylinder washing.

    It depends on the fuel used, and temperature of the engine parts, i.e. high temperature engine parts + gasoline is going to vaporize very quickly (and not wash down the bore) But as the engine parts are colder or alternative fuels may be used (injecting far more alcohol which tends to cool parts as it evaporates) the late injections can become problematic not just with cylinder washing but with vaporization/atomization.
    Thank you. Unfortunately i do not have the Rpm setting to go off of. Just the ECT setting.

    I actually understand what your saying. I really think i went to far with my injection timing. Trying to spray after the EVC and trying PPV has i get fuel smell in the oil. So maybe some cylinder wash i suppose. Could also be the cause of darker plugs no matter what i do.

    I will attempt to move my injection timing earlier based on my cam card to minic spraying on the IV at idle since i dont have the luxary of rpm based calculations. Might just have to settle for what works best overall.

    Also i didnt change my makeup values to reflect my ECT value. Would this have caused any driveability issues? I had some stumbling over 3k.
    Thanks again
    1997 30th SS. Torqhead 24x, TFS heads, 223/235 cam, 4l80e, S60 D1SC 14psi

  3. #603
    Senior Tuner kingtal0n's Avatar
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    Quote Originally Posted by anniversaryss View Post
    Thank you. Unfortunately i do not have the Rpm setting to go off of. Just the ECT setting.
    I think gen4 ecu does. I know many stand-alones do also.


    I actually understand what your saying. I really think i went to far with my injection timing. Trying to spray after the EVC and trying PPV has i get fuel smell in the oil. So maybe some cylinder wash i suppose. Could also be the cause of darker plugs no matter what i do.
    Keeping the plugs clean and white... is a product of running a/f ratio usually. Keep the a/f between 14.8 and 15.2:1 while driving/cruising normal.
    Also make sure you are using the right plug. I am using TR6's but switching to an iridium TR7 style so I can turn up the power.



    I will attempt to move my injection timing earlier based on my cam card to minic spraying on the IV at idle since i dont have the luxary of rpm based calculations. Might just have to settle for what works best overall.

    Also i didnt change my makeup values to reflect my ECT value. Would this have caused any driveability issues? I had some stumbling over 3k.
    Thanks again
    Gota watch the wideband and timing to really tell whats happening there. I've never heard of poor injector timing causing a drivability issue on a hot gasoline engine. Maybe with ethanol or cold engines.

    I stopped around 5.95 to 6.05 ranges in my gen3 application. It seems to offer the fuel savings (slight) while also avoiding spray into an open intake valve all together. The cam is small so there is very little overlap loss. Plus the engine has stock exhaust manifolds and a turbine so the exhaust gas pressure probably pushes exhaust back into the cylinder through overlap at low rpms, which would further reduce fuel washing out the valve (theory)

  4. #604
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    Quote Originally Posted by kingtal0n View Post
    I think gen4 ecu does. I know many stand-alones do also.




    Keeping the plugs clean and white... is a product of running a/f ratio usually. Keep the a/f between 14.8 and 15.2:1 while driving/cruising normal.
    Also make sure you are using the right plug. I am using TR6's but switching to an iridium TR7 style so I can turn up the power.





    Gota watch the wideband and timing to really tell whats happening there. I've never heard of poor injector timing causing a drivability issue on a hot gasoline engine. Maybe with ethanol or cold engines.

    I stopped around 5.95 to 6.05 ranges in my gen3 application. It seems to offer the fuel savings (slight) while also avoiding spray into an open intake valve all together. The cam is small so there is very little overlap loss. Plus the engine has stock exhaust manifolds and a turbine so the exhaust gas pressure probably pushes exhaust back into the cylinder through overlap at low rpms, which would further reduce fuel washing out the valve (theory)
    Thank you again for answering.
    I just need one clarification. The makeup table. Do i transfer the whole normal table to the makeup table or jist the 154 and up from the normal to the makeup like the pcm has stock. Stock is 5.55 from 154 up and the entire makeup table is 5.55.
    1997 30th SS. Torqhead 24x, TFS heads, 223/235 cam, 4l80e, S60 D1SC 14psi

  5. #605
    Senior Tuner kingtal0n's Avatar
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    judging by what I see in the stock makeup table it should be fine to move it wherever you moved the normal table.

    I'm not even sure makeup table does anything. And if it does it seems like a negligible amount of fuel since the factory is using 5.55

  6. #606
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    Quote Originally Posted by kingtal0n View Post
    judging by what I see in the stock makeup table it should be fine to move it wherever you moved the normal table.

    I'm not even sure makeup table does anything. And if it does it seems like a negligible amount of fuel since the factory is using 5.55
    Ok. I was just wonderig since i moved my normal into the mid 6s but left the makeup at 5.55 if that would have caused any issue. But guess not. Id go out and test. But cant right now
    1997 30th SS. Torqhead 24x, TFS heads, 223/235 cam, 4l80e, S60 D1SC 14psi

  7. #607
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    great info in this thread.

    it there a sticky, or how to for dummys?

  8. #608
    Quote Originally Posted by bk2life View Post
    great info in this thread.

    it there a sticky, or how to for dummys?
    I have an EOIT explained video, for Gen III... The actual amount you push it back is quite subjective, however seeing richer fuel numbers essentially indicates you and burning more efficiently. There are so many factors to this it is harder to go deeper than that, and if you would like to, read this thread from the start and it gets quite into a lot of theory and so on.

    Most do this just to clean up the raw fuel smell that comes with overlap and a catless exhaust. It won’t completely go away, but it will make your eyes water that much less lol.

    Link to videos is in my signature. It will show you which tables and how to calculate it.

  9. #609
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    Any of you guys adjusting EOIT and having fuel in your oil?