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Tunning issue or bad 4l60e??

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Old 09-12-2013, 03:13 PM
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Exclamation Tunning issue or bad 4l60e??

i recently finished doing a small simple h/c/i in my 98 ls1 z28. 243 heads/ls6 cam all suporting bolt ons no stall.it is untuned.when the car was stock when i would floor it it would shift perfect.now that i did the h/c/i i took it to the track only to have my rev limiter bouncing.it shifts perfect under normal driving but when you floor it it does not shift..any ideas?

I know its h/c/i but its nothing big thats why i assume the tune is not that bad.

Any input is appriciated thanks in advance.
Old 09-12-2013, 03:53 PM
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Is it doing that in all gears or only certain ones?

Is the trans stock or modded? Do you race in Overdrive/4th or put it in D/3rd?



I have seen cars where MAF tuning caused the trans to slip at WOT. If you are racing in D/3rd and it's only flaring on the 2-3 shift, a Sonax HD 2-3 shift valve installed in the transmission valvebody will help (or at least it did on mine).

If it is hitting the limiter in all gears at WOT I would be inclined to look harder at the tune before assuming the transmission is bad.
Old 09-12-2013, 04:52 PM
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I usually race it from 1st then manually shift to 2nd then work my way up..4l60e is stock .
1st time it did it i was manual shifting .it did going to second.second run i left it in d (3) it shifted to 2nd but bounced off limmiter going to 3rd .
Old 09-12-2013, 06:21 PM
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Check your WOT TPS -voltage-. Over 4.75V will be a
short-term fault and short-shift you. But it would not
shift late, it would shift early.

"Bouncing off the limiter" like whup-whup-whup-shift
is just a matter of stretcing the RPM across the converter
and waiting for MPH to catch up - a simple tuning issue,
any more power or vehicle weight can make that happen.

Staying stuck in the limiter with no upshift ever, that's
something else. Ought not to happen just by hardware
swapping.

Which is it? Or did you lift too soon to know?
Old 09-12-2013, 06:35 PM
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Originally Posted by jimmyblue
Check your WOT TPS -voltage-. Over 4.75V will be a
short-term fault and short-shift you. But it would not
shift late, it would shift early.

"Bouncing off the limiter" like whup-whup-whup-shift
is just a matter of stretcing the RPM across the converter
and waiting for MPH to catch up - a simple tuning issue,
any more power or vehicle weight can make that happen.

Staying stuck in the limiter with no upshift ever, that's
something else. Ought not to happen just by hardware
swapping.

Which is it? Or did you lift too soon to know?
I wanna say i was lifting at the correct time
Old 09-12-2013, 06:47 PM
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It just needs to be tuned mist likely. I always recommend leaving it in D or OD, you'll never out shift the PCM.
Old 09-13-2013, 04:19 AM
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If the voltage was to high would you adjust it with the throttle body set screw and then do a relearn?
Old 09-13-2013, 05:18 AM
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Originally Posted by nj02z
If the voltage was to high would you adjust it with the throttle body set screw and then do a relearn?
Break off the locating tab and slot the mountings holes.
Old 09-13-2013, 09:17 AM
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Don't manually shift it. It can cause what you are describing on its own unless you shift way early. Like over 1500rpm early.

Also sometimes traction loss can cause mine to hit the limiter and sometimes you have to lift throttle to get it to shift.



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