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

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: What are the odds of all injectors(or however many it takes for truck not to start) get clogged up. Truck was running fine and now it won't start.

Hi there. Check the fuel injectors for power to the harness on each injector. Make sure that there is a voltage reference. If there is no voltage reference, then there may be an issue with the main harness from the...

Q: Water linking only into the passenger side soaking the carpet.

Hi, thanks for writing in. It sounds like you may have a clogged AC drain from debris. I recommend having the drain cleaned out from the engine compartment. If you would like help, consider having an expert automotive technician from...

Q: 1994 Chevy C1500 won't start even when jumped

Either your battery is discharged to the point it won't take a jump or your battery cables are loose/damaged/corroded. If the vehicle has no lights whatsoever and it won't crank, the problem definitely has to do with the battery. A...

Related articles

P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...
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.
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.