Mercury Grand Marquis sudden acceleration problems

Filed Jan 20, 2023 · Acceleration, Electrical · CA · crash

I started Mercury with foot on break like normal. Shifted into reverse. Car accelerated backwards at full speed. Brakes did not stop car. Attempted to shift into neutral but went into drive instead. Car accelerated forward at full speed with my foot still on break. Car hit metal post and tree knocking them down and dragging the tree 50 to 60 feet before stopping with my foot still on the break. Car had stopped accelerating. I turned off the ignition. This unintended acceleration had happened before. Two different dealers attempted to fix the problem. Both of them thought they had been successful but it happened again. Previously, applying the brakes stopped the car, but not this time. Someone could have been injured severely or killed.

Filed Mar 29, 2022 · Engine · 100,000 miles · GA

The contact owns a 2007 Mercury Grand Marquis. The contact stated that while the vehicle was idling, the RPM’s revved up and the vehicle lunged forward. The contact depressed the brake pedal and the RPM’s decreased. There were no warning lights illuminated. The vehicle was not diagnosed or repaired. The manufacturer was not notified of the failure. The failure mileage was approximately 100,000.

Filed Mar 9, 2021 · Acceleration · 78,013 miles · IL

I was driving in town and several times when I slowed down to stop at a stop sign or corner, after braking my car accelerated by itself. The engine revved up and made the car jump forward. I had to slightly release the brake snd brake harder to stop and avoid going into the intersection.

Filed Jan 30, 2018 · Acceleration, Engine · 39,000 miles · NJ

Tl* the contact owns a 2005 mercury grand marquis. While driving approximately 5 MPH and then depressing the brake pedal to slow the vehicle down, the vehicle accelerated without warning. To avoid crashing into the preceding vehicle, the contact was able to veer to the right and continue driving. There was no warning indicator illuminated. The failure recurred three times. The vehicle was taken to porter ford (600 ogletown rd, newark, de 19711) where it was diagnosed that the throttle body motor assembly was sticking and needed to be replaced. The vehicle was repaired. The manufacturer was not contacted. The approximate failure mileage was 39,000.

Filed Aug 2, 2017 · Acceleration · 88,000 miles · OH

Tl* the contact owns a 2001 mercury grand marquis. The contact stated that while driving at 65 MPH, the vehicle accelerated rapidly without warning. The contact tried to depress the brake pedal and disengaged the cruise control but neither attempts to slow the vehicle were successful. The contact was able to slow the vehicle down only by depressing the accelerator pedal again after a period of unintended acceleration. The dealer was not contacted about the failure. The manufacturer was made aware of the issue and referred the contact to the dealer. The failure mileage was 88,000. Updated 10/24/17

Filed Mar 2, 2017 · Brakes · 130,000 miles · VA · crash

Vehicle would not stop when foot brake was applied. When brake was applied vehicle lunged forward. Driving on a main road, passing through a school zone and approaching a stop light. This was the second time vehicle would not stop in the past two months. I hit the rear of another vehicle damage occured.

Filed Nov 28, 2016 · Acceleration · 50,000 miles · OH

Tl* the contact owns a 2001 mercury grand marquis. The contact stated that the vehicle accelerated without warning. The dealer was unable to diagnose the failure. The vehicle was not repaired. The failure mileage was 50,000.

Filed Apr 27, 2016 · Engine, Fuel system · 75,000 miles · WA

The vehicle recently experienced two sudden acceleration events in two days 15 miles apart while decelerating and using the brake in what could only be related to an intermittent failure of the electronic throttle control. While on vacation during a 75 deg evening with the car at operating temperature I was navigating some s turns high on a bluff at 30mph. While coming into a corner with my foot on the brake and slowing to around 20mph the car suddenly accelerated. I hit the brakes hard, turned away from the corner to avoid going over the cliff and turned off the key. All this happened in less then 5 seconds. The next day mid afternoon after driving 20 miles I was leaving a park and traveling on a level straight road at around 25mph. Coming up to a stop sign I let off the gas and started applying the brake (like the day before) at about 15mph the car violently accelerated. I hit the brakes hard again, the rear tire started spinning and it pushed the car through the crosswalk past the stop sign and into oncoming traffic by about 4ft before I got the engine shut off. Once again this all happened in a matter of seconds. After a restart everything was normal again. I drove around 250 mi to get home without any further incident. Two weeks prior to these events I had the car at the dealer to program a new transponder key, reset the keyless entry and test the throttle to see if the initial deadband could be adjusted (no adjustment was done). After the incident I returned to the dealer and they said they have never heard of this problem, there are no recalls or tsbs, and the ECM would not datalog anything since there was no trouble light. They said there was nothing they could do. I consider this unsatisfactory, deem it a major safety defect and ford should be required to correct this immediately. A quick search reveals I am not the only one who has experience this.

Filed Nov 17, 2015 · Acceleration · 218,000 miles · GA

Tl* the contact owns a 2001 mercury grand marquis. While the vehicle was stopped, the vehicle accelerated without warning. The contact was able to pull over to the side of the road. The vehicle was taken to an independent mechanic where it was diagnosed, but the technician could not determine the cause of the failure. The vehicle was not repaired. The manufacturer was not notified of the failure. The failure mileage was 218,000. The VIN was not available.

Filed Aug 24, 2015 · Acceleration · 58,300 miles · WI

Tl* the contact owns a 2006 mercury grand marquis. The contact stated that while driving at 10 MPH attempting to engage the brakes, the vehicle suddenly accelerated without warning. The failure recurred three times. The vehicle was taken to a dealer but was not diagnosed or repaired. The manufacturer was made aware of the failure. The failure mileage was 58,300.