Question about 2005 Chevrolet Impala
My 2005 Impala (3.8L V-6, automatic) exhibits a strange noise when slowing down toward a stop. This always occurs around 17-16-15 mph as the car decelerates through this range, and sounds like a "scape." It is totally independent of the brake pedal being applied; no difference with brakes on or off. The noise doesn't occur until after the car has warmed up thoroughly, usually after it's been running for at least 5 minutes and has been driven several miles. The noise becomes more pronounced with time as the car warms up. It seems to be coming from under the hood, more-or-less on the driver's side but I can't be completely positive of this. It's almost certainly on the engine-compartment side of the firewall. If the car is thoroughly warmed up and decelerated to about 17 mph and kept at that speed, the noise resembles a piece of metal being used to scratch across asphalt. Once the speed goes above or below about 17 mph, the noise ceases. The noise is independent of whether the car is in "drive" or has been shifted to a lower gear. The car has been put into gear, brakes on, and the engine revved up past the RPM it would normally show at around 17 mph, then the accelerator released; the noise does not appear as the RPM decreases. There is no trace of noise as the car accelerates through the 15-16-17 mph range. The transmission shifts smoothly. At first I was afraid this might be a transmission issue; however, a technician has observed this condition and has expressed the opinion that it might possibly be caused by a defective or improperly calibrated wheel sensor in the ABS brake system, which tries to activate the ABS momentarily. However, I have seen no "ABS" light on the dash -- not even a flicker, and I have checked for this in the dark. I also feel no hint of any automatic braking action when this noise occurs. I should add, this car is a police-package vehicle. It was excellently maintained and I have the complete service record which is practically flawless -- this car was not used in enforcement work. The mileage was 96,000 when I purchased it and I've driven it about 400 miles. The car looks, drives and rides like new. No matter what's causing it, this is an ugly noise and should not be there. Any ideas? Thank! Mike in Raleigh NC
Speed sensitive issue could more likely be a loose heat shield on the exhaust system. this would change with speed and heat. check hangers and connecters on exhaust, I've come across a muffler clamp that set up quite a rattle as it vibrated around the ex. pipe. could be a bent dust shield on one of the disc brakes that is rubbing on the rotor but would likely change with steering direction. take off and check the belt pulleys and idlers for a loose bearing assembly.
Is there any "clunking" when going from f to reverse? drive train joints could be responsible, and they would be sensitive to power up or deceleration differences. usually more of a vibration and not a loud noise however.
Posted on Mar 06, 2015
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Posted on Jan 02, 2017
It sounds like the TPS throttle position sensor isn't working correctly. You need to find out what your fuel pressure is. If it's below specs., a new fuel pump will be needed.
Posted on Jun 20, 2008
Check for exhaust leaks. Esp Leaks toward the front of the car. Hold your hand over the tail pipe using a rag and see where the loud hissing noise comes from. Repair the leaks and I bet the backfiring goes away
Posted on Feb 09, 2009
Best advice.....take it to AAMCO....they do a check on the transmission system for FREE. They will let you know probable cause of your problem.
Posted on Mar 11, 2009
Clutch would show different ugly symptoms - it is definately a warped/warn rotor and/or brake pads from high speed deceleration or "riding the brakes".
Fairly easy to fix, probably 2-3 hours of work for each corner
Posted on Apr 03, 2009
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