4l60e rebuild gone wrong
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On The Tree
Joined: Sep 2018
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From: New Zealand
4l60e rebuild gone wrong '97 camaro z28 (LT1) with single piece 4l60e.
no trouble codes,
After starting out, it shifts into second fine, but it never shifts into third, just stays in second. Reverse works fine.
Any idea where to begin troubleshooting? (only tried running it on jack stands so far)
Used a scan tool and can see the computer commanding third, but it just stays in second forever.Shifts back to first fine when coming to a stop.
no trouble codes,
After starting out, it shifts into second fine, but it never shifts into third, just stays in second. Reverse works fine.
Any idea where to begin troubleshooting? (only tried running it on jack stands so far)
Used a scan tool and can see the computer commanding third, but it just stays in second forever.Shifts back to first fine when coming to a stop.
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On The Tree
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TECH Junkie
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Thread Starter
On The Tree
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Thread Starter
On The Tree
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hmm ok, if its not the sprag then if its mechanical all it could be is the 3-4 assembly? Although if that was wrong I would have expected it to 'run away' in third, wheras i'm just not getting the shift at all. It air checked on the pump fine prior to installation 
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On The Tree
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Ok ok disregard all that, this is whats actually happening (took it for a drive)
All gears shift smoothly and fine, did some WOTs, etc, all looking good.
The TCC definitely locks, but it seems to unlock with not much throttle. Any slight hill and it appears to unlock.
I took it for a drive with tech2 - The TCC duty cycle increases where it should, but only up to 90%. Even when i command TCC lockup, the duty cycle will only go up to 90% (I have retained PWM functionality). When its locked, the TCC slip speed varies from -30ish to +150ish. I also see P1870 intermittantly, but no check engine light.
I have installed the Sonnax oversized TCC regulator valve. The P1870 is new since rebuild, so I assume I have done something wrong. ANy suggestions appreciated.
All gears shift smoothly and fine, did some WOTs, etc, all looking good.
The TCC definitely locks, but it seems to unlock with not much throttle. Any slight hill and it appears to unlock.
I took it for a drive with tech2 - The TCC duty cycle increases where it should, but only up to 90%. Even when i command TCC lockup, the duty cycle will only go up to 90% (I have retained PWM functionality). When its locked, the TCC slip speed varies from -30ish to +150ish. I also see P1870 intermittantly, but no check engine light.
I have installed the Sonnax oversized TCC regulator valve. The P1870 is new since rebuild, so I assume I have done something wrong. ANy suggestions appreciated.
Thread Starter
On The Tree
Joined: Sep 2018
Posts: 161
Likes: 4
From: New Zealand
Thread Starter
On The Tree
Joined: Sep 2018
Posts: 161
Likes: 4
From: New Zealand
Am i likely to risk torque converter damage having it running at 90% duty cycle? The computer commands TCC lockup correctly, but i assume its only running at 90% duty cycle, because thats what the reading says, and because of the P1870 code.
Some run at 98% at certain times stock.
Ok ok disregard all that, this is whats actually happening (took it for a drive)
All gears shift smoothly and fine, did some WOTs, etc, all looking good.
The TCC definitely locks, but it seems to unlock with not much throttle. Any slight hill and it appears to unlock.
I took it for a drive with tech2 - The TCC duty cycle increases where it should, but only up to 90%. Even when i command TCC lockup, the duty cycle will only go up to 90% (I have retained PWM functionality). When its locked, the TCC slip speed varies from -30ish to +150ish. I also see P1870 intermittantly, but no check engine light.
I have installed the Sonnax oversized TCC regulator valve. The P1870 is new since rebuild, so I assume I have done something wrong. ANy suggestions appreciated.
All gears shift smoothly and fine, did some WOTs, etc, all looking good.
The TCC definitely locks, but it seems to unlock with not much throttle. Any slight hill and it appears to unlock.
I took it for a drive with tech2 - The TCC duty cycle increases where it should, but only up to 90%. Even when i command TCC lockup, the duty cycle will only go up to 90% (I have retained PWM functionality). When its locked, the TCC slip speed varies from -30ish to +150ish. I also see P1870 intermittantly, but no check engine light.
I have installed the Sonnax oversized TCC regulator valve. The P1870 is new since rebuild, so I assume I have done something wrong. ANy suggestions appreciated.
What did you use for assembly lube?
Did you presoak the clutch plates?
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On The Tree
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I'm glad your saying 90% is fine, but the reason I assume(d) its not enough, is because of the p1870 code. - though its not tripping the check engine light, and seems to be intermittant.
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On The Tree
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when it hits 4th gear, TCC lockup gets commanded 'on', and the TCC lockup goes 25%, 50%, 75%, 89% (or sometimes 90%). Never goes up to 100%. Then sometimes p1870 will trip in history.
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On The Tree
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I understand theres two methods to solve the issue:
1. Installing a larger spring which essentially bypasses the PWM functionality.
2. Installing an oversized valve from Sonnax to retain the PWM fuctionality.
I went with option 2. Reamed the boar out and wet air tested it prior to installing the valve body - All was perfect.
So I can safely eliminate the TCC regulator valve as the cause. I think that leaves me with the Actuator feed valve, or a leak on the input shaft. I wet air tested the actuator feed valve and it passed (prior to install), so the only thing i can think of is a leak from the input shaft. I'm sure I installed the o ring correctly, but there was some where on the input shaft spline - do you know if wear on the input shaft spline could cause a leak in the TCC circuit?
I am more than willing to tear the transmission back down, but i'm not confident enough in my troubleshooting steps to do so. I'm not really inclined to pull the trans out, replace the input shaft and seal, and re-install the transmission without having a more valid troubleshooting analysis, which is why i think i'm way over my head at this point.
I've done extensive research into the PWM circuit, and a leak at the input shaft is about the only thing I can think of.
1. Installing a larger spring which essentially bypasses the PWM functionality.
2. Installing an oversized valve from Sonnax to retain the PWM fuctionality.
I went with option 2. Reamed the boar out and wet air tested it prior to installing the valve body - All was perfect.
So I can safely eliminate the TCC regulator valve as the cause. I think that leaves me with the Actuator feed valve, or a leak on the input shaft. I wet air tested the actuator feed valve and it passed (prior to install), so the only thing i can think of is a leak from the input shaft. I'm sure I installed the o ring correctly, but there was some where on the input shaft spline - do you know if wear on the input shaft spline could cause a leak in the TCC circuit?
I am more than willing to tear the transmission back down, but i'm not confident enough in my troubleshooting steps to do so. I'm not really inclined to pull the trans out, replace the input shaft and seal, and re-install the transmission without having a more valid troubleshooting analysis, which is why i think i'm way over my head at this point.
I've done extensive research into the PWM circuit, and a leak at the input shaft is about the only thing I can think of.
