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Thread: seeking help. I rebuilt a 04 5.7 hemi (NGC3)

  1. #1
    Tuner in Training
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    seeking help. I rebuilt a 04 5.7 hemi (NGC3)

    After completing the rebuild and upgrading the cam in my 5.7 hemi it ran terrible, talked the the guys at summit and they said get a tune on it, of course i had to learn to do it my self since the entire build i did in house. A few issues that i've had so far include poor idle, dying at stops, flashing lightning bolt on dash, cam position sensor MIL, O2 rear MIL, front O2 High voltage MIL.

    I have dug through the interwebs and hptuners forums to help solve some of the issues and some have helped but created new problems, such as i got it to idle and not die at stops but now it wont start if the motor is hot (150+). The flashing lightning bolt i feel is a by product of something i changed as well i just can seem to track down the gremlin responsible. Oh and another thing when i find a viable solution, due to the age, i dont have the same functions the user has such as the special features and controls in the scanner appears blank so i cant reset adaptives or anything.

    short list of changes; stage two turbo cam 547 550 lift @ 224 duration. 3" longtube headers. AEM UEGO 30-4411 wideband(serial components enroute)
    removed cats on both sides no boost yet replaced plugs (ignition coils soon) b
    thats pretty much it, it runs rich at idle but shortly after giving it ANY throttle leans way out, i know after i get the wideband hooked into my pc this will help.

    If you know anything that can help or can link a post with these questions that would be much appreciated.

    Files
    will get to you shortly

  2. #2
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    Quote Originally Posted by chadillac View Post
    After completing the rebuild and upgrading the cam in my 5.7 hemi it ran terrible, talked the the guys at summit and they said get a tune on it, of course i had to learn to do it my self since the entire build i did in house. A few issues that i've had so far include poor idle, dying at stops, flashing lightning bolt on dash, cam position sensor MIL, O2 rear MIL, front O2 High voltage MIL.

    I have dug through the interwebs and hptuners forums to help solve some of the issues and some have helped but created new problems, such as i got it to idle and not die at stops but now it wont start if the motor is hot (150+). The flashing lightning bolt i feel is a by product of something i changed as well i just can seem to track down the gremlin responsible. Oh and another thing when i find a viable solution, due to the age, i dont have the same functions the user has such as the special features and controls in the scanner appears blank so i cant reset adaptives or anything.

    short list of changes; stage two turbo cam 547 550 lift @ 224 duration. 3" longtube headers. AEM UEGO 30-4411 wideband(serial components enroute)
    removed cats on both sides no boost yet replaced plugs (ignition coils soon) b
    thats pretty much it, it runs rich at idle but shortly after giving it ANY throttle leans way out, i know after i get the wideband hooked into my pc this will help.

    If you know anything that can help or can link a post with these questions that would be much appreciated.

    Files
    will get to you shortly
    The flashing lightning bolt is a throttle body light. Could be an aftermarket throttle body issue or possibly something else.

    You likely are very rich at lower RPM, but without a wideband thats a educated guess at best. Ive encountered the warm start issue after cam swap several times. I usually pull some start up fuel or add some start up airflow in the warmer tables.

    With an aftermarket cam, you will likely need to raise idle a little vs stock, add some timing and airflow in the lower rpm/startup tables.

    You can try "repoll parameters" and see if you can get some of the scanner functions to work correct, unfortunately 2004 has very little support, but Ive had some scanner issues even on 2005 and 2006 as well so it may very well be a software issue.

    As you seem to realize with your last couple of lines, posting your tune file would be a great start for some help!

  3. #3
    Tuner in Training
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    Thank you white1, it?s the stock throttle body, with that being said I just found that I never reconnected the brake booster vacuum line after I dropped the motor in, maybe it?s related to the throttle issue. I did that before leaving for work (regional truck driver) will test again if I make back at a decent time.

    What you said about fuel makes sense unfortunately I did the polar opposite bc I read a GM thread saying to add fuel at high temps. Will correct the tables to reflect that.

    Side note, I installed a 180* thermostat during the build and set ring gap at 20 and 23 for future boost.

    I?ll try the scanner side to re-poll at my stop this afternoon. And get those files posted.

  4. #4
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    A hard start at operating temp is generally too much or not enough fuel. Its tricky to see which unless you have a wideband and an external power source for it. Most vehicles will drop power for a split second when you crank it. (my tuning wideband plugs into the cigarette lighter)
    If it starts easy with a little throttle input you can try raising the startup airflow, but if you go too high it can create other issues.

    The brake booster could certainly cause the lightning bolt. The PCM is seeing reduced vacuum and opening the throttle to try and stay running, but the the throttle feedback is not what is expected.

    WHAT I DO (not saying its 100% correct or wrong, different people do things different ways)
    Raise idle rpm 50-100
    Raise start up airflow by about 10%
    Cut about 10-15% out the VE table below 1500 or so RPM
    Raise startup spark to around 4-5*

    That SHOULD get you started up ok, and idling well enough to tune from there.

    Id personally try going back to the stock startup fuel tables since you found the vacuum hose off, and will be making several other changes at the same time

  5. #5
    Tuner in Training
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    sorry for the delay, i did evil things to this last tune attempt, notice the pw at 100+ are double or triple the original value. Also am i disabling the rear O2s correctly and why cant i use OL while i wait for my hardware for the wide band

    stock and final tunes attacctched.

    must connect to repoll...

    thank you for the posts btw really opening my eyes to possiblities
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