Skip the auto shop - Our mechanics make house calls

Q: Runs fine with the map sensor vacuum line plugged off

asked by on

If I leave the map sensor connected the enine load up and stalls. I already replaced the tps,map sensor,injectors, distributer , fuel pump and filter, ecm.

My car has 180000 miles.
My car has an automatic transmission.

A: Hello, the map sensor is an input of engine...

Hello, the map sensor is an input of engine load. When the map sensor is disconnected it will set a fault code which is emission base and check engine will come on,this cause the system to go into a default mode. It uses engine vacuum as a measurement of that load. There is also an electronic aspect - the map sensor uses a five volt reference (0-5 volts). Zero volts would represent low engine load and 5 volts would be high load. You need the correct vacuum at the sensor to operate. Things that could affect this are having a vacuum line that’s plugged to the sensor or blocked at the intake manifold. There would be several steps to take in a diagnosis process. The overall health of the engine can create false input information to the computer (ECM). If you’d like, a certified technician from YourMechanic can come to your location to diagnose the issue.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

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: Leaking rubber fuel line

That is most likely the injection pump feed line that is leaking. This line, if leaking, will need to be replaced. The key must be off and out of the ignition to prevent accidental startup of the fuel feed...

Q: Air Filter Replacement

The air filter does not require grease on it. The filter oil should be enough. Grease can actually degrade the material of the filter and may shorten the lifetime of the part. If you want to have the air filter...

Q: Randomly shuts off no matter how much fuel is in vehicle, no acceleration/stalling when pushing pedal.

Hello and thank you for writing in! When was the last time you changed the fuel filter? The filter can have a huge effect on how much fuel is delivered to the engine. With the age of your vehicle, there...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
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...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.