I have a 2008 Chevrolet Silverado 2WD, 4.8L V8, 4A, LT1 w/ 4 dr extended cab, with 23K miles. I get an occasional harsh shift from 2nd to 3rd, usually when the engine is somewhat cold. Also when I slow down to a stop, it sometimes feels like someone slightly bumped from behind, and I get this feeling again on takeoff from a dead stop. Also, if I slow down for a turn (but don't stop), and then accelerate again, often there is a hesitation before it accelerates, even though I give a healthy push on the pedal. Then when it does accelerate, there is a ****/whiplash as it hooks up again. I also have a rough idle occasionally, but I cannot attribute this to any particular situation, as it sometimes happens when the engine is cold, and also happens when the engine has been warm for a while. I've looked up these problems and found TSB numbers for all, and I'm going to take it to the dealer anyways (since its still under warranty), but I wanted to see if anyone had any ideas so I don't get the runaround at the dealer and get a worthless fix and/or a lot shoulder shrugging.
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May 8, 2004 - 19 posts - 9 authors
Auto Trans not shifting correctly from 2nd to 3rd Under the Hood. ... Become an EliteExplorer. Lithuania. 1999 5.0. Join Date: Jun 2003. Posts: 107 ... When this happens, the transmission will skip to the next gear like you said.
Jan 13, 2013 - Uploaded by James Burns
... Doctor, explores the causes of harsh shifting in automatic transmissions. ... Early diagnosis is important to ...
1-2 shift is delayed and harsh, may not shift into OD: Check TPS for smooth and linear electrical response over the entire range of motion. If not, replace or EPC (Electronic Pressure Control) solenoid failed. Easy fix in pan. Fix as soon as possible or hard parts will eventually break. Start with the simple and check the transmission fluid level and condition.Secondly, put a line pressure gauge (or visit a local trans shop) on the pressure test port and go for a drive to verify proper line pressure. Base pressure at idle in P,N,OD should be around 70psi and around 140psi in R. Max line pressure should be at least 190psi at WOT in 1st or 2nd, 225psi is optimum. If base pressure is low, trans or pump is worn out. If max pressure is low, check EPC solenoid. If reverse is slow to engage, and line pressure does not come up to at least 130psi in reverse, replace the boost valve with a Transgo 0.500" boost valve (easy fix in pan). No 1st or 4th available; trans shifts 2nd to 3rd by itself in D or OD and locks the converter : ShiftA solenoid failed. Easy fix in the pan. Or a wiring problem from PCM to trans.. or PCM. Good luck and keep me posted.
What you may define as "second and third" may be TCC lockup
(torque convereter clutch). Your TCC is PWM (pulse widtrh modulated) and should be applied in increments. There is a TCC solenoid in the pump body, and a TCC control solenoid in the valve body.
Your TCC control solenoid MAY be the problem, but the screen on the solenoid may be dirty. Or the converter clutchor solenoid may be
Since 2nd is band applied and 3rd is clutch applied, only a force motor failure would let them both be harsh, and if that was the case
even going into neutral/drive or neutral/reverse would be harsh.
it can be the shift solenoid in the trans there is one for 1st and 2nd then there is one for 3rd and fourth easy to change drop pan they are right there.about 40 to 60 at dealer for solenoid and of course fluid and filter about 60.00