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I have a 2003 chevy impala. When I hit the gas (whether it be a light tap or hit it pretty hard), my car kind of waits a second, jerks and then takes off (revs go kinda high when it's waiting). To me it kind of feels like the first gear is waiting to catch and then it catches and it jerks. This only happens when going from being stopped (ie at a stop light). Does anyone have any idea what this could be?

It's been doing this for a long while now. Been meaning to have it looked at, just haven't had time or money.

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  • How smoothly are you pressing on the gas pedal after taking off? Tapping or hitting it hard doesn't sound like a "smooth" application of the throttle. That may simply be the reason why the car is hesitating.
    – Dude318is
    Jun 1, 2011 at 17:18
  • smooth. by tap i mean barely touching the gas to get it to go. no matter how smooth i push the gas it'll jerk
    – DForck42
    Jun 1, 2011 at 17:56
  • Hmmm, maybe tranny is slipping. How many miles on the car? Maybe a tranny fluid flush will cure the problem.
    – Dude318is
    Jun 1, 2011 at 20:33
  • @Dude318is, ~130k.
    – DForck42
    Jun 1, 2011 at 21:00
  • Sounds like about the right time for a tranny flush.
    – Iszi
    Jun 4, 2011 at 17:00

5 Answers 5

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The Chevy Impala's 4T65E transmission was said to feature an updated Pressure Control Solenoid starting in 2003. This was a major issue in the 2000-2002 model years. But, there are still many people with the 2003MY vehicles that are experiencing the same issue as you. The vehicle may or may not already have illuminated a Check Engine Light due to the issue. Even if not, it most likely still has stored a fault that could verify that the Pressure Control Solenoid is faulty. The trouble code for this would be P1811 (max adapt, long shift).

The component is located behind the side cover of the transmission and should take ~5 hours for a quality mechanic to complete. It is a rather big job and involves lowing the front cradle to gain access. If you're not 100% comfortable with a job of this magnitude this then get the vehicle to a well known transmission shop.

Below: Pressure Switch Assembly (It is possible that the you can get the switch separate from the entire assembly. That's something you or your mechanic can look into)

enter image description here

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This problem sounds like one I saw in BMW 7 series. There was a rubber disc that sat between the transmission and the drive shaft(assuming RWD), and when the bolt holes became damaged the cars would do this. It was basically the thing would spin, and then catch up and hit. Once the disc was replaced, problem went away. Look at the drive train connection first, and see if the problem is simple.

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  • it's front wheel drive
    – DForck42
    Oct 4, 2011 at 21:21
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    For future reference the rubber disc is called a Flex Disc.
    – cinelli
    Mar 29, 2013 at 4:25
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Had same problem on 2008 impala. No MIL lights, transmission fluid clean with new filter. After coming to a stop transmission hesitated then jumped into gear. Problem ended up being Throttle Position Sensor on the throttle body (not pedal).

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The 4T65E transmission features a "forward" clutch that is engaged in 1st gear forward only. Once it shifts into 2nd, this clutch is released. It is only applied in 1st. The inner piston seal gets worn or the piston area gets worn where the seal rides. What is happening is once you slow down and stop, the line pressure which is at minimum because the throttle isn't touched, fails to pressurize the clutch piston completely to engage the forward clutch plates. When you "tip in" or hit the throttle to take off, the line pressure jumps and builds enough pressure to apply the piston, thereby engaging the forward clutch. This is why the transmission hesitates or bumps into 1st gear on takeoff when hot. The complete remedy is to pull the transmission and do a total overhaul, replacing the parts that are worn in the forward clutch housing and a new improved inner piston seal. The other remedy is to manually downshift into 1st gear by using the transmission selector lever when coming to a stop. When you select low range with the shifter lever, the line pressure is raised from about 100psi to about 175psi which helps engage the forward clutch piston and overcomes the pressure leak on the inner piston seal.

Note that it also is possible that the EPC or (PCS) solenoid before mentioned can also cause this problem as the EPC solenoid sticks and doesn't regulate the line pressure to about 100psi when idling in drive. This can be verified by using a transmission pressure gauge and driving down the road while watching line pressure. If the line pressure is accurate, then the inner piston seal is the problem and not the EPC (electronic pressure control) solenoid.

Note that this forward clutch in the 4T65E is the same exact clutch that is used in the 440T4 transmission that was used for years without this problem. However with the 440T4 transmission, the forward clutch remained engaged in all "forward" ranges so this never developed into a problem.

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  • Good answer, BTW. Very well written information as to the issue and what needs to be fixed.
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Apr 4, 2015 at 21:50
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It is the valave body, there is a valve that wears out and does not seal properly all the time, causeing low pressure which causes the slip, then the valve seals causing it to take off. It is a known propblem in the impala transmissions, but GM wont do a recall

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    It would be good to paste a link to a resource used explaining the common issue. Or a photo of assembly showing the location of the component / part kit if available.
    – cinelli
    Mar 28, 2013 at 22:26

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