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Transmission shifting rough

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Old 04-22-2018, 11:20 PM
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Default Transmission shifting rough

Hey guys, kinda new here. My wife just bought a 2005 Chevrolet Impala base 3.4l 4t65e (NOT the HD) with 165K. It was previously a fleet vehicle for a real estate company.

When we got it it shifted hard into 1st from a stop but 2, 3, And 4 weíre smooth. Replaced the torque converter, filter, and pan gasket and immediately got a code for the torque converter clutch circuit stuck open or malfunctioning.

Replaced the torque converter clutch solenoid with a new BWD unit from Napa, and now it is smooth in first, and will roast the tires if you punch it, but 2, 3, And 4 absolutely slam into gear EVERY SINGLE SHIFT. So bad that if youíre accelerating such as to get to freeway speed or are under load climbing a hill, you hear a short chirp like a tire slipping.

Any ideas? Iím not getting any codes now.

Getting real tired of having to repeatedly fix GM autos... our pontiac Grand Prix had just as many issues before we got rear ended and were forced to get a new car....
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Old 04-22-2018, 11:54 PM
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OK, have to ask, why did you replace the converter for a harsh shift from first?

If I bought a fleet vehicle with 165K, and I dropped the tranny, why just stop at converter?

What was the code before you replaced the converter?
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Old 04-23-2018, 12:21 AM
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All of the automatic cars weíve had, all shifting and/or slipping issues STARTED with the TC after 145-150K miles. This one started with slipping at highway and hard shift at stop.

Tc fixed hard shift at stop, and THEN gears 2 3 and 4 started hard shifting and code P0740 came up, which in the owners manual supplied with the car and my GM 97-11 repair manual show as being torque converter clutch control.

Replaced the solenoid and still having exactly the same the same issues with no DTC codes or CEL.
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Old 04-23-2018, 12:23 AM
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There were no codes BEFORE TC
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Old 04-26-2018, 01:25 AM
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A 3.4 really doesn't have the cajones for barking the tires during shifts, however, clutches engaging hard while the torque converter is locked would do it. I'm wondering if the converter clutch is locking when it isn't supposed to . . . ?

How are the downshifts when it is in this mood?
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Old 04-26-2018, 02:35 AM
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Downshifts are smooth as butter, even when you floor it. Maybe not in hard shift, but the 3.4 CAN burn rubber at least in 1st.

It just now threw a code P0742 today, and is still slamming gears on every upshift. The torque converter clutch solenoid is brand new. Could the pressure switch cause the computer to read an error on behalf of the TCC?

Just canít figure out why a converter and a TCC solenoid would cure hard shift/slip from stop and then cause all remaining gears to shift hard. SUPPOSEDLY the previous owner had had a filter and gasket done with a fluid flush, and the fact that the pan doesnít have a single speck of dirt on it supports that, so Iím disinclined to believe that ití* dirty fluid or clogged passage ways....
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Old 04-26-2018, 02:40 AM
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I did notice driving the hill home that driving uphill, if you donít dig into the pedal a little bit it will stutter slightly, similar to that of a misfire from bad plugs/coils. If you punch the gas just slightly from that stuttering point it downshifts smoothly and runs as if nothing can bother it
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Old 04-26-2018, 03:38 AM
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Originally Posted by HotrodRay View Post
Downshifts are smooth as butter, even when you floor it.
Probably has the overrun clutch disengaged, which makes sense for having overdrive selected.

Originally Posted by HotrodRay View Post
but the 3.4 CAN burn rubber at least in 1st
Definitely not beating up on the 3.4 , at least not in this way.

In this case, a shift that "barks" the tires is bad. Wheelspin from romping on it is a whole different deal.

Originally Posted by HotrodRay View Post
Just canít figure out why a converter and a TCC solenoid would cure hard shift/slip from stop and then cause all remaining gears to shift hard.
Yeah, it'* almost like the TCC is working in reverse.

Originally Posted by HotrodRay View Post
I did notice driving the hill home that driving uphill, if you donít dig into the pedal a little bit it will stutter slightly, similar to that of a misfire from bad plugs/coils. If you punch the gas just slightly from that stuttering point it downshifts smoothly and runs as if nothing can bother it
Sounds like it expects (in PCM mapping) that the converter clutch would be disengaged during the last struggle before shifting down. If the converter clutch did open at that time it would allow it to rev a little and stay nearer it'* power band.
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Old 06-30-2018, 10:15 PM
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can you command the tcc on and off. what is the tcc doing during the failure.could you have crossed the tcc pwm connector with the p/c solenoid connector.while you were in the
side cover did you replace the p/c solenoid if not I would recommend it as it has a high failure rate. Are you able to watch data. with most trans codes the default is high line psi which causes hard shifts. p0740 doesn't show as a fault code for this trans but the p0742 does.Watch the tcc release psi pid and verify if it is working.
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Old 06-30-2018, 10:23 PM
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The TCC and PC solenoid were replaced one at a time so that no plugs would be crossed. I don't have any means of tracking data. The code my reader is showing IS a P0740. Shifting is now getting worse.
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