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Thread: Problem at 6300rpm !!!

  1. #1

    Question Problem at 6300rpm !!!

    I have a 2003 Tahoe with built 6.0 and turbo kit im having a problem where the car pulls until it reaches 6300 rpm it feels like its misfiring with no pops or bang or its hitting a rev limiter but in the tune its been raised till 6700rpm and the problem still occurs so the car wont reach the shift point which has been set 6500rpm it will stay in the 6300rpm range and do the misfiring shit.

    please if someone can chime in and help.tune00.hptproblem.hpl
    2003 Tahoe 5.3L turbo PTE 7675 604rwhp on 14.7 psi
    2011 Silverado 416ci turbo 9 psi 629rwhp
    2006 Cadillac cts-v lingenfelter 427ci 630hp package
    2010 Silverado LSx 427 with maggy 650 awhp

  2. #2
    Tuning Addict 5FDP's Avatar
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    You do have abuse mode set to 6,000rpm for whatever reason. Set that to 8,000rpm. You have other weird settings in there for some stuff but try that first.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

  3. #3
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    I have a C4 Corvette I tune that has this issue too. 0411 ecu swap on the LT1 and almost like clockwork it will act like it hits a rev limiter at 6100-6300 rpm. Rev limit was set to 7500 (forged pistons, forged crank, and H-beam rods). I never figured the issue out so hopefully someone has some input here.

  4. #4
    Quote Originally Posted by 5FDP View Post
    You do have abuse mode set to 6,000rpm for whatever reason. Set that to 8,000rpm. You have other weird settings in there for some stuff but try that first.
    I will change it and try to see if it will solve the problem ill keep you updated
    2003 Tahoe 5.3L turbo PTE 7675 604rwhp on 14.7 psi
    2011 Silverado 416ci turbo 9 psi 629rwhp
    2006 Cadillac cts-v lingenfelter 427ci 630hp package
    2010 Silverado LSx 427 with maggy 650 awhp

  5. #5
    Potential Tuner
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    Is this happening when in the boost at 6500rpm but not when out of boost? If it's happening in boost but not out of boost I have the following thoughts. If it happening not in boost...then ignore the following.

    Not sure if you have swapped injectors or not, but keep in mind, at higher RPMs there is less time the injector can pulse to inject fuel. While it might be able to keep up and lower RPMs, those higher rpms leave very little time for injection. Perhaps a larger injector is needed? Take a look at your injector pulse time (INJ B1 or INJ B2) in your scanner. Take 6500 rev/min multiply by 1min/60s and then invert it to get sec/rev => 0.009sec/rev. Then multiply that by 2 because the came spins half the speed of the crank. So that's only 18ms for the injector to be able to inject all it needs to at that rpm. At lower rpms (let's say 3250rpm) you have 36ms for injection and most stock injectors can probably handle that. If your INJ B1 or INJ B2 are trying to inject longer than the valve it open, then your injector is not large enough. I ran into this when I turbo'd my little ecotec motor. Injectors were maxing out before I got above 5k with boost. Went from 45# to 60# injectors and it solved the issue. Just a thought.....

  6. #6
    Quote Originally Posted by four_by_nut View Post
    Is this happening when in the boost at 6500rpm but not when out of boost? If it's happening in boost but not out of boost I have the following thoughts. If it happening not in boost...then ignore the following.

    Not sure if you have swapped injectors or not, but keep in mind, at higher RPMs there is less time the injector can pulse to inject fuel. While it might be able to keep up and lower RPMs, those higher rpms leave very little time for injection. Perhaps a larger injector is needed? Take a look at your injector pulse time (INJ B1 or INJ B2) in your scanner. Take 6500 rev/min multiply by 1min/60s and then invert it to get sec/rev => 0.009sec/rev. Then multiply that by 2 because the came spins half the speed of the crank. So that's only 18ms for the injector to be able to inject all it needs to at that rpm. At lower rpms (let's say 3250rpm) you have 36ms for injection and most stock injectors can probably handle that. If your INJ B1 or INJ B2 are trying to inject longer than the valve it open, then your injector is not large enough. I ran into this when I turbo'd my little ecotec motor. Injectors were maxing out before I got above 5k with boost. Went from 45# to 60# injectors and it solved the issue. Just a thought.....

    The car has a set of ID 1050x injectors so theres plenty of room left and fuel pressure is good.
    2003 Tahoe 5.3L turbo PTE 7675 604rwhp on 14.7 psi
    2011 Silverado 416ci turbo 9 psi 629rwhp
    2006 Cadillac cts-v lingenfelter 427ci 630hp package
    2010 Silverado LSx 427 with maggy 650 awhp

  7. #7
    Quote Originally Posted by 5FDP View Post
    You do have abuse mode set to 6,000rpm for whatever reason. Set that to 8,000rpm. You have other weird settings in there for some stuff but try that first.
    I have set the abuse mode to 8,000rpm with no difference still the same?
    2003 Tahoe 5.3L turbo PTE 7675 604rwhp on 14.7 psi
    2011 Silverado 416ci turbo 9 psi 629rwhp
    2006 Cadillac cts-v lingenfelter 427ci 630hp package
    2010 Silverado LSx 427 with maggy 650 awhp

  8. #8
    Tuning Addict 5FDP's Avatar
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    Did you pull the plugs?

    What plugs are they and what gap are you running?
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

  9. #9
    Advanced Tuner
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    thinking in spark plug gap too, how much boost running?

  10. #10
    Quote Originally Posted by 5FDP View Post
    Did you pull the plugs?

    What plugs are they and what gap are you running?
    The plugs which im using is NGK tr7 gaped to .22 .
    This problem happens even when its on low boost like 7 psi
    2003 Tahoe 5.3L turbo PTE 7675 604rwhp on 14.7 psi
    2011 Silverado 416ci turbo 9 psi 629rwhp
    2006 Cadillac cts-v lingenfelter 427ci 630hp package
    2010 Silverado LSx 427 with maggy 650 awhp

  11. #11
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    code?

    trans abuse?

    2101 code?

  12. #12
    Quote Originally Posted by lukearmstrong1990 View Post
    code?

    trans abuse?

    2101 code?
    No codes or REP it feels like its rev limiting at 6300rpm so i checked everything with no luck.
    Trans abuse is disables as you can see in the tune ^^
    2003 Tahoe 5.3L turbo PTE 7675 604rwhp on 14.7 psi
    2011 Silverado 416ci turbo 9 psi 629rwhp
    2006 Cadillac cts-v lingenfelter 427ci 630hp package
    2010 Silverado LSx 427 with maggy 650 awhp

  13. #13
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    Minor input. Your shift RPM's are very close to your shift MPH's. It will only shift full throttle when both are met. I would shift based on rpm, so lower your WOT shift MPH so they don't both go true at the same time.
    Phil K.
    02 Camaro SS 5.7L LS1
    01 Silverado 1500HD 6.0L LQ4

  14. #14
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    Also, I noticed that your INJ B2 really falls while INJ B1 stays and levels off. At some points they differ by 25%, that is a lot. Not sure why.
    Phil K.
    02 Camaro SS 5.7L LS1
    01 Silverado 1500HD 6.0L LQ4

  15. #15
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    I just had a Silverado SS that did the same thing. It was almost like a rev limiter at 6200-6300. We changed valve springs and injectors and plugs and plug wires and coils. Long story short, we replaced the crank sensor and that fixed it. It never had a DTC at all.

  16. #16
    Quote Originally Posted by pknowles View Post
    Minor input. Your shift RPM's are very close to your shift MPH's. It will only shift full throttle when both are met. I would shift based on rpm, so lower your WOT shift MPH so they don't both go true at the same time.
    Tried that with no luck
    2003 Tahoe 5.3L turbo PTE 7675 604rwhp on 14.7 psi
    2011 Silverado 416ci turbo 9 psi 629rwhp
    2006 Cadillac cts-v lingenfelter 427ci 630hp package
    2010 Silverado LSx 427 with maggy 650 awhp

  17. #17
    Quote Originally Posted by kevin87turbot View Post
    I just had a Silverado SS that did the same thing. It was almost like a rev limiter at 6200-6300. We changed valve springs and injectors and plugs and plug wires and coils. Long story short, we replaced the crank sensor and that fixed it. It never had a DTC at all.
    Crank sensor has been changed with no difference I'm doubting the reluctor wheel where the crankshaft had 58x and been changed to 24x.
    2003 Tahoe 5.3L turbo PTE 7675 604rwhp on 14.7 psi
    2011 Silverado 416ci turbo 9 psi 629rwhp
    2006 Cadillac cts-v lingenfelter 427ci 630hp package
    2010 Silverado LSx 427 with maggy 650 awhp

  18. #18
    Exact same thing here. 2001 Corvette. Mostly stock with headers. 6300 rpm pops like a rev limiter. Only full throttle because of normal delay in shift but can reproduce every single time by just putting shifter in any gear and light throttle up to 6K to 6,300. Anyone find a cure yet? I was going to lowering WOT shift speeds down to get the trans to shift a little earlier so it does not hit 6K so hard.

  19. #19
    I found the issue the car was valve floating baaad i changed valve spring and the car is mint

  20. #20
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    Quote Originally Posted by tahoels1 View Post
    I found the issue the car was valve floating baaad i changed valve spring and the car is mint
    I was just going to say, sounds like a valve float issue.