However with the 440T4 transmission, the forward clutch remained engaged in all "forward" ranges so this never developed into a problem. 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. If the line pressure is accurate, then the inner piston seal is the problem and not the EPC (electronic pressure control) solenoid. This can be verified by using a transmission pressure gauge and driving down the road while watching line pressure. 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. 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. The other remedy is to manually downshift into 1st gear by using the transmission selector lever when coming to a stop. 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. This is why the transmission hesitates or bumps into 1st gear on takeoff when hot. 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. 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. The inner piston seal gets worn or the piston area gets worn where the seal rides. Once it shifts into 2nd, this clutch is released. The 4T65E transmission features a "forward" clutch that is engaged in 1st gear forward only. That's something you or your mechanic can look into) If you're not 100% comfortable with a job of this magnitude this then get the vehicle to a well known transmission shop.īelow: Pressure Switch Assembly (It is possible that the you can get the switch separate from the entire assembly. It is a rather big job and involves lowing the front cradle to gain access. The component is located behind the side cover of the transmission and should take ~5 hours for a quality mechanic to complete. The trouble code for this would be P1811 (max adapt, long shift). Even if not, it most likely still has stored a fault that could verify that the Pressure Control Solenoid is faulty. The vehicle may or may not already have illuminated a Check Engine Light due to the issue. But, there are still many people with the 2003MY vehicles that are experiencing the same issue as you. This was a major issue in the 2000-2002 model years. Urgh.The Chevy Impala's 4T65E transmission was said to feature an updated Pressure Control Solenoid starting in 2003. However, to replace it the trans needs to be dropped and that's always. It also may feel like driving over rough pavement or rumble strips. (48-104 km/h) during steady state driving with the transmission not actively shifting gears. Also the consensus seems to be it is a pressure control solenoid that is causing the issue. My 2002 chevy impala shakes whem i accelerate the gas between 40-60 mph. Thankfully I know people who have had this problem for years in their Impala and their transmission never gave out. It's started happening again on occasion now that temperatures are dipping, but unlike before it's nowhere close to being as violent, and it happens much more rarely.ĭitto to the transmission fix being a band aid. I put in a bottle of Lucas Oil transmission fix (without taking fluid out), and it went away for about 9 months or so. ![]() Lowest price guarantee on accessories for your Chevrolet Impala and the fastest shipping available. Complete installation instructions and lifetime technical support on all Transmission Cooler purchases. It used to be really bad, and I'm talking knock-coffee-out-of-my-hand bad. Call 80 to get Expert Service ordering a Transmission Cooler for your 2002 Chevrolet Impala. If the ambient temperature is about between 40 and, say, 55, it might do it once out of every ten starts. For some reason, it doesn't seem to matter what the trans temp is. It's only occasional, and it only does it in cool weather. FWIW, mine does the shift-bang from stop as well.
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