Q: I changed my TPS because of bad idle, now it stalls when I come to a stop after exceeding 50mph. What's the problem?

asked by on

I changed my TPS, because before it was idling really bad to the point of shutting off before I even put it in drive. Yet now that I have changed it, it stalls when I come to stop and the acceleration is struggling. I also cleaned the idle air control valve because it was dirty. To reset the computer I disconnected the negative on my batter and the Throttle position sensor for thirty minutes. Before I reattached the negative I reattached the TPS, yet it still doesn't seem to want to match up and work right. What seems to be the problem?

Hello, It sounds like you may have a faulty MAP sensor that may be creating an adverse signal to the change in engine load. 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]((https://www.yourmechanic.com/services/manifold-absolute-pressure-sensor-map-sensor-replacement), 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?

Need advice from certified mechanic? Get help now!

Over 1,000 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!
  1. Home
  2. Questions
  3. I changed my TPS because of bad idle, now it stalls when I come to a stop after exceeding 50mph. What's the problem?

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: Q: How do I turn on the heated mirrors?

The heated mirrors can help give you visibility out of your side mirrors by eliminating any rain, ice, or condensation. The heated mirrors will automatically turn on when the rear defroster is turned on.

Q: Q: Brake lights stay on

The most common cause for the lights to stay on is the brake light switch. I recommend that you have a mechanic, such as one from YourMechanic, come by and run an inspection to diagnose your brake light issue.

Q: Mustang started and then died

There can be a large variety of reasons as to why your Mustang is not starting. When you add to the equation that it has been sitting for a couple of years, it may mean your Mustang is facing multiple...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
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.