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Thread: Geartrain noise in 4L60E second gear causing "knock" retard

  1. #1
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    Geartrain noise in 4L60E second gear causing "knock" retard

    I am about to pull my hair out with this one. Have any of you seen a transmission cause false knock only in 2nd gear??? I can hear a whine in the transmission at about 4,000+ in second gear. At 4,400 I start seeing knock retard that quickly peaks 8. I can slightly reduce the "knock by retarding the timing to rediculous values but not eliminate it. I made a run from a standing start to better than 90 mph and practically no knock in 1st or 3rd gear but massive amounts in 2nd that vanishes quickly after a WOT 2-3 shift, despite the engine being under more load, with more timing and less rpm.

    Prior to the 0411 swap I ran a LT4 knock module and rarely ever saw knock retard even with 26-28 total advance.

    Edit---This was meant for the OBD2 board...Darn phone.
    Last edited by Fast355; 04-12-2013 at 07:12 PM.

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    maybe talk to Dana at Probilt and find out what could cause the racket in 2nd gear?





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    EFI GearHead ! EagleMark's Avatar
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    Moved your thread for you. Wish I had an anwer but never dealt with this before.

    Can you actually here some noise in second gear?

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
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    Quote Originally Posted by EagleMark View Post
    Moved your thread for you. Wish I had an anwer but never dealt with this before.

    Can you actually here some noise in second gear?
    I appreciate you relocating this for me. Posting from my phone gets me sometimes.

    Yes I can, sounds almost like a quiet gear drive the way it whines.

    I messed around with it today and it responded very well to a Ramjet timing map. 30-31* total advance, 11.8:1 PE air/fuel ratio and 93 octane gasoline turned it into a rocket compared to how it was running. On another note....I am out of fuel at WOT now. Guess that TPI is going on sooner than later

    The weirdest part of it all is sometimes it will retard the timing and other times it won't. I am seeing the same amount of retard at 18* timing as I am at 30-31*. I attached a few screen shots of 1st and 2nd gear runs and a WOT 1-2 shift.
    Attached Images Attached Images
    Last edited by Fast355; 04-13-2013 at 01:46 PM.

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    This is the stock spark map creating 8* of retard in 2nd gear! With this much knock on the stock tune, I do not feel this knock is actually knock, it has to be false knock.
    Attached Images Attached Images
    Last edited by Fast355; 04-13-2013 at 02:08 PM.

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    EFI GearHead ! EagleMark's Avatar
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    The weirdest part of it all is sometimes it will retard the timing and other times it won't.
    Sure it's not Cat protection?

    That log picture 3 looks like it may be trans torque reduction for shift?

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    Quote Originally Posted by EagleMark View Post
    Sure it's not Cat protection?

    That log picture 3 looks like it may be trans torque reduction for shift?

    Cat Protection is Disabled along with EGR.

    Torque management on 1-2 and 2-3 are both set more than stock at 40%. I had it at 50% reduction from stock, but with over 400 ft/lbs of torque in front of it the weak 4L60E was slipping between gears even with elevated line pressure, a transgo HD2 shift kit, and Corvette Servo. I put it back stock and I still didn't like the feel. I then put in more torque management and it really cleaned up the shift.

    Look at the KR though in the 3rd picture it is 5.1*. Picture 1 was a 2nd gear pull running the Ramjet spark map and it peaked less than 1* at 4,800 rpm. Picture 2 has me less than 1* retard as well. The 4th picture is showing the stock timing map setting of 21* creating more than 8* knock retard! I am not even sure how that is possible at 11.8:1 air/fuel ratio.
    Last edited by Fast355; 04-13-2013 at 02:28 PM.

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    EFI GearHead ! EagleMark's Avatar
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    Correct me if I'm wrong but torque management shows up as spark retard? Have no idea how you get more retard from less timing?

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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    Quote Originally Posted by EagleMark View Post
    Correct me if I'm wrong but torque management shows up as spark retard? Have no idea how you get more retard from less timing?
    Torque management shows up as spark retard, but it does not show up as Knock retard. Notice the sharp dip on the upshift back to around TDC.

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    So I remembered something that I ran across years back on a different swap. The 96-02 L30 305 Vortec and OBDII LT1, LT4 and L99 engines all use the same knock sensor and it is different than the 96-02 L31. At this point I am thinking of swapping to the L30 knock sensor or properly torquing it to 14 ft/lbs. I seem to remember an overtightened knock sensor becoming too sensitive.

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    EFI GearHead ! EagleMark's Avatar
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    Over tightening will do it and ruin the knock sensor.

    Strange how OBDI knock sensors match engine displacement? Can you compare a 305 cal/bin/tun and a 350 cal/bin/tun? In EFI Live there's a ton of Knock sensor settings.

    What's a HP Tuner file extension?

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    I believe they are .BIN files. That being said I have a EFI Live .TUN file for both the 305 and 350 Express vans.

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    HPTuners uses .HPT.

    also, having a sensor too loose will also pick up false knock, or at least it does on 60V6 applications.
    1995 Chevrolet Monte Carlo LS 3100 + 4T60E


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    I don't suppose you ever get to 4400rpm in 4th... 2nd and 4th gear in the 4L60Es run the rear planetary gearset, and it's possible that this particular trans may have some needle bearings starting to wear. How many miles on it? Also, does it make any gear noise in reverse?

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    Quote Originally Posted by sherlock9c1 View Post
    I don't suppose you ever get to 4400rpm in 4th... 2nd and 4th gear in the 4L60Es run the rear planetary gearset, and it's possible that this particular trans may have some needle bearings starting to wear. How many miles on it? Also, does it make any gear noise in reverse?

    Never have heard any noise in reverse. This trans is the original from 97 and has 80,005 miles as of this morning. Transmission has been JUNK since 38,000 miles. Just keeping it until I find the time to track down a 4L80E, rebuild it and swap it in.

    Considering 3,100 rpm in 4th is 101 mph, 4,400 rpm is not going to happen with the current gearing and tire size.
    Last edited by Fast355; 04-14-2013 at 09:30 PM.

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