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Thread: 7427 upgrade tuning help understanding

  1. #31
    Fuel Injected! PlayingWithTBI's Avatar
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    Quote Originally Posted by typhoonss92 View Post
    copcar injectors are 83lb @ 15psi. I have mine set at 22 when it is cooler our and goes down to almost 20 when hot, I live in Fl.
    So with all the different places/excel sheets to calculate I should be 96-100lb per injector. I think I need to go a touch higher because I am maxing out the VE table in a few places but the problem for me is the red spring I have for the fpr maxes out at 22 and I would like to be able to got to 23 or 24 but can't find a spring, may just go external fpr unless anyone knows where to get a spring that has a range of lets say 20-26ish psi.

    I got this spring from ebay, and running @ 28PSI with the adjuster barely turned in. I think it's from a 95-96 7.4L, so this may not help unless you go higher than you mentioned.
    https://www.ebay.com/itm/GM-TBI-28ps...97.m4902.l9144
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    Last edited by PlayingWithTBI; 4 Weeks Ago at 01:41 PM.

  2. #32
    Super Moderator dave w's Avatar
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    Attached are more spreadsheet screen shots from the same combined data logs previously posted.

    Injector Duty Cycle should increase with engine load / engine rpm.

    BLM's and WBO2 data are not aligned. Closed Loop WBO2 tuning will have better overall performance!

    For a daily driver 16197427, I like tuning with stock injectors, stock spring, with stock injector parameters. Perhaps, using higher flowing 16197427 7.4 liter injectors, stock spring, with 7.4 liter injector parameters is an option to think about?

    Spark Advance is challenging, perhaps an experiment with minimum temperature for Knock Retard set to 151 Celsius will provide valuable data?

    dave w
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  3. #33
    Super Moderator dave w's Avatar
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    Quote Originally Posted by dave w View Post
    Attached are more spreadsheet screen shots from the same combined data logs previously posted.

    Injector Duty Cycle should increase with engine load / engine rpm.

    BLM's and WBO2 data are not aligned. Closed Loop WBO2 tuning will have better overall performance!

    For a daily driver 16197427, I like tuning with stock injectors, stock spring, with stock injector parameters. Perhaps, using higher flowing 16197427 7.4 liter injectors, stock spring, with 7.4 liter injector parameters is an option to think about?

    Spark Advance is challenging, perhaps an experiment with minimum temperature for Knock Retard set to 151 Celsius will provide valuable data?

    dave w
    I tune a daily driver 16197427 with two Oxygen Sensors, the factory O2 sensor and the WBO2. I do not use simulated NBO2 data.

    I tune a daily driver 16197427 with factory default AFR fuel ratios.

    dave w

  4. #34
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    Quote Originally Posted by dave w View Post
    Attached are more spreadsheet screen shots from the same combined data logs previously posted.

    Injector Duty Cycle should increase with engine load / engine rpm.

    BLM's and WBO2 data are not aligned. Closed Loop WBO2 tuning will have better overall performance!

    For a daily driver 16197427, I like tuning with stock injectors, stock spring, with stock injector parameters. Perhaps, using higher flowing 16197427 7.4 liter injectors, stock spring, with 7.4 liter injector parameters is an option to think about?

    Spark Advance is challenging, perhaps an experiment with minimum temperature for Knock Retard set to 151 Celsius will provide valuable data?

    dave w
    Anything with a 7.4 and the 7427 used a 46 lb/hr injector @ 28 psi. Barely enough fuel to support a stock 5.7 Vortec much less anything making any power at all.

    I use 14.1 stoich on our E10 here. The fuel trims always seem to fall into line more easily as do the WOT air/fuel. 12:1 around peak torque and lean out to about 12.6:1 at higher rpm.

  5. #35
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    Thanks for all the info, guess there is no spring for the 20-26 range, there used to be a gold one that would do 16-26 from what I read but have not seen one. So I guess my options are the big block injector that is 80-85# with a stock spring at about 15-16psi from the excel spread sheets calculations or get an external vfpr. I have the blockoff for the fpr and the special adaptors for the tbi so I can use 6-an fittings. If I go the route of external I have heard multiple different setups, keep your fpr but add the external in the return line, not sure how this allows more fpr if it has to go thru the stock one first. Second was blockoff then external, but I have also read that there is issues with not regulating the fuel correctly something to do with the little hangy thing in the diaphram not being there. Anyone have an external and how they set it up.

    I looked thru the perameters on the injectors and really only see the volume, the 2 injector flow rates. there is bpw sync and async. The rest seems to do with the o2 which I think I may need to make changes to because I have mid tube headers and the o2 is about 12-14 in downstream of where the stock one was. It is 3 wire and heated.

    One other thought is I have a 50mm bored sb tbi. I have also read there may be tuning needed for this because of the extra air but nothing on what is needed to be changed, should I just look at a bigblock bin and see what is different for flow characteristics, there are probably only a few that need changed if anyone knows what they are that would be awesome. gonna get a bin now and see.

    I was thinking this motor was aproxx 350hp & 400-415 tq but after reading a few setups with dyno results of very similar basically all the same but cam and cam is maybe .01 to .04 higher lift I am seeing 380-420hp. again none were the same and just est of what I think I have. So with what they place I bought the injectors says the injector flow is possibly being off and possibly having a little more power than I thought this could be why I still do not have enough fuel pressure and why the VE table is going beyond 100 in the spreadsheet.

  6. #36
    Super Moderator dave w's Avatar
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    Quote Originally Posted by Fast355 View Post
    Anything with a 7.4 and the 7427 used a 46 lb/hr injector @ 28 psi. Barely enough fuel to support a stock 5.7 Vortec much less anything making any power at all.

    I use 14.1 stoich on our E10 here. The fuel trims always seem to fall into line more easily as do the WOT air/fuel. 12:1 around peak torque and lean out to about 12.6:1 at higher rpm.
    The link to gearhead-efi TBI injector flow rates: http://www.gearhead-efi.com/Fuel-Inj...d-part-numbers

    17104288 - Pink / Purple - 46pph @13psi - 7.4L / 454 - 94-95 *NOTE: Came with 30 PSI regulator used @ 26-32psi for 67-72pph

    17084304 - Black / Blue - 74pph - 7.4L / 454 - 91-93

    Daily Driver ... hmmm what does that really mean???

    dave w

  7. #37
    Super Moderator dave w's Avatar
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    Quote Originally Posted by typhoonss92 View Post
    Thanks for all the info, guess there is no spring for the 20-26 range, there used to be a gold one that would do 16-26 from what I read but have not seen one. So I guess my options are the big block injector that is 80-85# with a stock spring at about 15-16psi from the excel spread sheets calculations or get an external vfpr. I have the blockoff for the fpr and the special adaptors for the tbi so I can use 6-an fittings. If I go the route of external I have heard multiple different setups, keep your fpr but add the external in the return line, not sure how this allows more fpr if it has to go thru the stock one first. Second was blockoff then external, but I have also read that there is issues with not regulating the fuel correctly something to do with the little hangy thing in the diaphram not being there. Anyone have an external and how they set it up.

    I looked thru the perameters on the injectors and really only see the volume, the 2 injector flow rates. there is bpw sync and async. The rest seems to do with the o2 which I think I may need to make changes to because I have mid tube headers and the o2 is about 12-14 in downstream of where the stock one was. It is 3 wire and heated.

    One other thought is I have a 50mm bored sb tbi. I have also read there may be tuning needed for this because of the extra air but nothing on what is needed to be changed, should I just look at a bigblock bin and see what is different for flow characteristics, there are probably only a few that need changed if anyone knows what they are that would be awesome. gonna get a bin now and see.

    I was thinking this motor was aproxx 350hp & 400-415 tq but after reading a few setups with dyno results of very similar basically all the same but cam and cam is maybe .01 to .04 higher lift I am seeing 380-420hp. again none were the same and just est of what I think I have. So with what they place I bought the injectors says the injector flow is possibly being off and possibly having a little more power than I thought this could be why I still do not have enough fuel pressure and why the VE table is going beyond 100 in the spreadsheet.
    Attached is the PE Active AFR's for a 16197427 Daily Driver.

    It would be awesome to compare AFR's screen shots from other tuner members. I think posts with data are the most helpful for everyone wanting to learn tuning.

    dave w
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  8. #38
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    daily driver in my case. Well my truck see's maybe 5-6000 miles a year. 90% is highway miles and the motor is 2yrs old. ultimately this will be a toy almost at that point maybe 1 more year. Then a saturday fun driver and the track. only see's 93 octane since I built this motor and usually see 13-15mpg depends if I go past 50% throttle.
    I am looking on the site and around the web is there a 7.4L bin for $0D so I can do a compare with my bin just for the throttle body air difference between the stock and the 50mm bored one I have. I have seen a few but $0E so can't use the compare function.
    Last edited by typhoonss92; 4 Weeks Ago at 11:43 PM.

  9. #39
    Super Moderator dave w's Avatar
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    Quote Originally Posted by typhoonss92 View Post
    daily driver in my case. Well my truck see's maybe 5-6000 miles a year. 90% is highway miles and the motor is 2yrs old. ultimately this will be a toy almost at that point maybe 1 more year. Then a saturday fun driver and the track. only see's 93 octane since I built this motor and usually see 13-15mpg depends if I go past 50% throttle.
    I am looking on the site and around the web is there a 7.4L bin for $0D so I can do a compare with my bin just for the throttle body air difference between the stock and the 50mm bored one I have. I have seen a few but $0E so can't use the compare function.
    $OD is for the 4L60E, $OE is for the 4L80E

    The factory did not use the 4L60E with the 7.4 liter.

    Using two instances of TunerPro (side by side) is required to compare a $OD .bin file vs. $OE .bin file. Parameters from a $OE .bin file can be copied / pasted into a $OD .bin file.

    dave w

  10. #40
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    so after reading about tbi injectors and their vast difference in flow rates for the same injector size and thinking about the 65# injectors I have. even though the place I bought them said the flow is 73 @ 12.5, I rethought this and tried 70@13psi with the bump up to 21psi is about 88. I put that in the injector flow in the chip and it makes a huge difference, I also now get 75dc% at max rpm over 60dc% I was getting. I still think I need a little more fuel pressure but debating on how I will go about that since there is no spring between 23-27psi range, bigger injectors or external vfpr. The only thing I see kinda odd is idle map at 50-60 maxes out the ve table, actually above but it wont go that high. The other thing I am working on now is dfco. It seems to surge off throttle in deaccell. Is there any advice on the closed throttle timing table or should it be the saame as the open throttle table.

  11. #41
    Fuel Injected! brian617's Avatar
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    Quote Originally Posted by typhoonss92 View Post
    I still think I need a little more fuel pressure but debating on how I will go about that since there is no spring between 23-27psi range, bigger injectors or external vfpr. .
    I'm running the 94-95 big block spring @ 22 psi with the matching pump in the tank.
    89 K1500 Scottsdale 5.7L 5spd 3:42

    Build specs: 97 4 bolt main block 350ci, Eagle rotating assembly with flat tops and 4 valve reliefs, Dart 165cc/67cc Iron Eagle heads, Manely SS valves and springs 110lbs seat @1.7, GM Ram Jet cam 196/206 @.50 .431/.451, stock intake and throttle body, heads and intake gasket matched, Delco EP377 fuel pump @ 22 psi, 427 PCM.

  12. #42
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    besides the injector flow being changed when you up the psi or put in bigger injectors is there any other perameters or tables that need to be changed

  13. #43
    Super Moderator dave w's Avatar
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    The Injector Flow parameter is one of the most import parameters to determine in the tuning process.

    What an injector is rated to flow vs. what an injector is actually flowing vs. the injector flow parameter programmed in the chip are not always the same flow number.

    When a VE table correction is calculated to be greater than 100, one tuning option is to correct the injector flow parameter. The injector flow parameter is used by the computer to determine the injector Base Pulse Width (BPW). The larger the BPW value the more fuel the injector is spraying into the engine (for example a BPW of 6.3 milliseconds is spraying more fuel than a BPW of 4.4 milliseconds). When the VE table correction value needs to be greater than 100 the BPW needs to be larger so the injector will spay more fuel into the engine.

    The downside to changing the injector flow parameter when tuning, is ALL the previous "Tuning" is invalid and the "Tuning" process has to start ALL OVER again. Increasing the fuel pressure regulator spring has the same effect on the "Tuning" process as changing the injector flow parameter.

    The example below is a "Perfect Injector" that is rated to flow 72 lbs / hr, actual flow has been measured @ 72 lbs / hr with E10 fuel, and the .bin file is programmed for 72 lbs / hr. The perfect injector does not exist on any known make / model / year vehicle!!! The perfect injector is a MYTH!!

    A common "Tuning HACK" to correct for an IMPERFECT INJECTOR, is to trick the computer to increase the BPW by changing the injector flow programmed into the chip.
    Lowering the injector flow from 72 lbs / hr down to 70 lbs / hr will INCREASE BPW.

    The injector flow "HACK" has limits of about + / - 4 of the rated injector flow. For the example above the injector flow hack limit is between 68 lbs hr to 76 lbs hr. Injectors with lower rated flow will have a lower hack limit, example an injector rated to flow 22 lbs / hr will be about + / - 2 lbs / hr.

    dave w

  14. #44
    Fuel Injected! brian617's Avatar
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    Obviously you will have to fix your VE table, but generally you can get it close fast by lowering or increasing the whole table to counter the pressure difference. I my experience with using TBI injectors at higher than normal pressures, AE acceleration enrichment needs work.
    89 K1500 Scottsdale 5.7L 5spd 3:42

    Build specs: 97 4 bolt main block 350ci, Eagle rotating assembly with flat tops and 4 valve reliefs, Dart 165cc/67cc Iron Eagle heads, Manely SS valves and springs 110lbs seat @1.7, GM Ram Jet cam 196/206 @.50 .431/.451, stock intake and throttle body, heads and intake gasket matched, Delco EP377 fuel pump @ 22 psi, 427 PCM.

  15. #45
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    thanks Dave and Brian.
    Yes I have had to up the AE which made considerable difference and also PE a little. I have worked and reworked the VE tables as I make changes. I test, datalog run the log in history tables see what needs changed, then put csv into daves excel change the idle and off idle ve tables from the wbo2 sensor data, check for actual knock that has pulled timing, these knock sensors are very sensitive.
    I have the 65pph copcar injectors and the site I got them from sayd they flow at 73@12.5 which I think is bs. That is why I had my injector flow at 98 which calculated for the HP I am putting out would be correct, but I was only getting 65% injector duty cycle and 5200rpm 100kpa. which lead me to believe they do not flow that high. I changed my cacluations to 70@13psi with my fpr at 21 so I made the injector flow rate 90. this made a huge difference no skipping at high rpm just riped thru the rpm and dropped almost 2 sec off my 0-60 but injector duty cycle was only 75% which leads me to believe they really flow 65@13psi aproxx. I tried dropping down to 85 for the injector flow and it was so rich at idle it was trying to stall so I put the prior chip backin. The only place I am maxing out the VE table is at or right off idle 800-1000 rpm then everything else is fine. Not sure why it would want more fuel at idle than anywhere else. well guess I will tune and test and repeat.

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