I apologize for posting a car question in a truck forum, But I couldn't
find a Chevy forum here to ask my question.
I have a 2001 auto-trans Impala that normally shifts as smooth as silk.
Occasionally though after driving awhile it will begin to shift really
hard and rough through all of the gears.
After it sits overnight or for awhile it will go back to shifting smooth
again as if there is no problem at all.
The problem isn't too frequent.. but I was hoping that somebody could
steer me in the right direction what might be wrong so I will know what
I am up against here.
Thanks for any help.. It is much appreciated!
On Fri, 16 Nov 2007 01:39:45 -0500, email@example.com (Toad
First thing to do is have it scanned for codes. Some codes will cause
the tranny to raise the line pressure to max when they set. This
increase in pressure will often be felt as hard shifts.
Old Crow "Yol Bolson!"
'82 FLTC-P "Miss Pearl"
'95 YJ Rio Grande
BS#133, SENS, TOMKAT, MAMBM
Posted via a free Usenet account from http://www.teranews.com
On Nov 15, 11:39 pm, firstname.lastname@example.org (Toad Monster) wrote:
Though I can't specifically answer about your car, I can tell you that
Chevy's 4L60E trans has this same problem due to a design flaw with
the valve body. Transgo makes a rebuild/shift kit that fixes this
problem, if it is caught in time. One of the check ball seats gets
worn to the point it becomes slightly larger then the ball, allowing
it to sit in the hole and not come out. The kit replaces this with a
larger ball and addresses other issues.
Depending on the tranny in your Imp, you may have a similar problem.
Hope this helps a little bit.
This is probably related to the Pressure Control valve. Either its
sticking or the computer is detecting slippage. Sometimes cold weather
causes these valves to stick if they sit a little while.
Here's a possible related TSB:
Slips, Harsh Upshift or Garage Shifts, Launch Shudders, Flares, Erratic
Shifts and Intermittent Concerns, DTC P1811 or P0748 Set (Replace
Pressure Control Solenoid Valve Assembly) #00-07-30-002B - (07/19/2002)
2000-2002 Chevrolet Impala
The above condition may be due to any one of the following which may
affect line pressure output:
* Sediment inside the pressure control (PC) solenoid valve, causing the
PC solenoid valve to mechanically bind.
* Sediment in the valve body, causing the torque signal regulator valve
* Incorrect transaxle oil level.
(Now watch out for Snoman. If he see's your thread he might confuse your
4l65e with a Powerglide.)
I'm sure it will:
The updates are electrical, and the two issues in the valve body. But, the
4L65E fits the LS series small blocks, I don't know if they have the same
bolt pattern, or a dual bolt pattern.
I've yet to rebuild a 4L65E, but the valve bodies are visually different.
I don't know if the electronics are the same impedance either, but that can
be worked out any way.
Hmm, maybe I should ask the tranny expert of 1870, Snofraud and see
what he has to say about this? LOL
Thanks for the info though, I'll keep that in mind if I keep the Silvy
much longer then I plan too. Right now, it hard shifts a little, but
I know the transgo kit will correct the problem and that is something
that I can install myself.
I highly recommend the Trans-Go kit,
I especially recommend you install it yourself also. You'll take the time to
look at the filings and see if there is more clutch than steel, iron and
brass than any tranny shop would.
I was going to post on the pressure control solenoid:
Just to add on your post, these solenoid valves have the tendency for the
coil to break down: (wear and short internally) under the higher
temperatures that are generated by the slippage.
So I would use a scanner and look at the rpm and output shaft speed in third
gear. This is how the leakage and non operation is found.
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