Q: 2001 Mercury Villager. The engine surges in Neutral and Park. Normal in drive. But noise and jerk during gear change.

asked by on

2001 Mercury Villager. The engine surges in Neutral and Park. Normal in drive and reverse. But noisy and jerky during gear change. Changed transmission fluid just 1000 miles ago.
My car has an automatic transmission.

This may be a sign of a faulty MAP sensor as the vehicle responds adversely to a load put on the motor (i.e. putting it in gear, making turns (which makes use of the power steering pressure switch) turning on AC or engaging the brakes). The Manifold Absolute Pressure (MAP) sensor senses engine load and generates a signal that is proportional to the amount of vacuum in the intake manifold. The engine computer then uses this information to adjust ignition timing and fuel enrichment. When the engine is working hard, intake vacuum drops as the throttle opens wide. The engine takes in more air, which requires more fuel to keep the air/fuel ratio in balance. When the computer reads a heavy load signal from the MAP sensor, it adjusts the fuel mixture to slightly more rich than normal so the engine can produce more power. The computer will then retard (back off) ignition timing slightly to prevent detonation that can damage the engine and decrease performance. This may also be caused by other closely related components such as a dirty or failing mass air-flow sensor, a faulty throttle position sensor or potentially a vacuum leak. I would recommend having an expert from YourMechanic come to your location to diagnose and inspect your vehicle.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. 2001 Mercury Villager. The engine surges in Neutral and Park. Normal in drive. But noise and jerk during gear change.

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Car idles at high RPMs

Idling too fast can be caused by several things. But bottom line is that too much air is getting into the intake manifold. Manifold vacuum leaks are a common cause. Do a visual inspection to check for any vacuum hoses...

Q: My van is misfiring. Can I drive 400 miles before changing them? I'm traveling home now

Hi and thanks for contacting YourMechanic. If the Check Engine Light says that your vehicle has a misfire, then you will need to check the spark plugs and wires. I suggest replacing the spark plugs if they have hot spots,...

Q: Cleaned air mass flow light was red . now unplugged or plugged in . started noticing car was dying at red lights and stumbled high

It should be safe to drive a short distance to purchase a Mass Air sensor. As long as the engine is not stalling or overheating and take it easy driving you should be fine.

Related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...