Q: Replaced crankshaft position sensor, runs worse 2003 Chevrolet Tahoe

asked by on December 18, 2016

My vehicle has been running rough since last night (Saturday December 17). It would start up fine and run smooth, but after a mile or two it would suddenly lose power and rpm's dropped like a lead weight. After allowing it to sit for a minute or two, it'd start back up fine, then a couple miles later it would repeat the process. I tried changing the fuel pump, since it seemed like a fuel issue, with the way the engine acted like it was running out of gas. That didn't help. So I did some asking around and digging online, and found from other people's experience with the same issue, it was the crankshaft position sensor. So I picked up a new one and changed it out, without issue. But now when I turn on my truck it idles very rough and has very little power when pressing the gas pedal. It sounds like it's missing in the engine. And if you take your foot off the gas pedal the engine putters roughly for a second or two and shuts off. All electrical works good as well. So I don't know.

My car has 225000 miles.
My car has an automatic transmission.

Loss of power Inspection $94.99 - $114.99 Get a Quote

Hello - there are several possibilities for this kind of behavior. While it’s possible the crank position sensor could fail in this fashion, fuel supply (as you first thought) is also a real possibility. A failed fuel pump relay will act in this manner - run for a bit, get hot, stop passing current to the pump, stop pumping fuel - cool, repeat. In your defense, a failing fuel pump will act the same way! I would replace the fuel pump relay and fuel filter, then check fuel pressure while running (and losing power if this continues) to verify correct fuel pressure. Clogged or otherwise malfunctioning injectors can also act this way. I would recommend an engine inspection by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs.

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


Experienced Mechanic?

Earn up to $70/hr

What others are asking

My car won't detect my car key.
There is a technical bulletin 13-5-32 that covers this problem of no start with any key. The TSB says that the vehicle will need to have the anti-theft system radio transceiver module reprogrammed using the dealer IDS system with the...
Help? - 2003 Honda Civic
This may be related to several different things. It would be best to hook the car up to a scanner to diagnose using the trouble codes that would have registered in the car's computer (you should have a Check Engine...
Why is my steering wheel hard to turn and my EPS light on in my 2004 Mazda RX-8
Hi there. This is a common issue on your vehicle. Most of the time this is caused by a problem with the steering angle sensor. The sensor stops reading properly which causes the steering to act like this. There are...
Transmission won't go into reverse after clutch replacement
Hello. If your vehicle is no longer going into gear after a clutch service, it may be possible that an issue occurred while the service was being done. Perhaps a problem with the clutch fork, or hydraulic clutch mechanism that...
Making a clicking noise
What you are describing sounds like a failing CV joint (https://www.yourmechanic.com/services/axle-cv-shaft-assembly-replacement). A CV (Constant Velocity) joint is a shaft that connects the transmission to the wheels, essentially transferring the power from the drive train directly to the wheels. The CV...
Horn honks when the 10 minute run time times out.
Hello, thank you for writing in. This is security feature is designed to remind you the vehicle is still running to protect against thieves and high idle times. These idle times add to pollution, and are a main cause of...
1996 Jeep Grand Cherokee with 180,000 miles. As I'm driving it starts to sputter but still going the speed limit.
Sounds like the crankshaft position sensor is loosing connection when driving. Check the harness to the crankshaft position sensor and see if there is a loose wires or if the contacts can be loose when pushed against. The harness could...
2012 nissan Altima and it won't start but battery is good, Do you know which fuse I need to replace for the car to start again?
If the engine is cranking relatively rapidly, then the battery is probably OK, but strictly speaking the only way to tell if a battery is really "good" is to perform a load test (https://www.yourmechanic.com/services/battery-is-dead-inspection). There are many fuses (not to...
I'm replacing my gas cap with a regular black one though I drive an e85 flexfuel that's got a yellow cap, is that ok?
Gas caps are no longer mundane, low tech devices. The only replacement gas cap that a knowledgeable, professional mechanic will recommend is an OEM cap, supplied by the dealer, and matched to your vehicle VIN number. Any other cap, including...

Related articles

What Is Dry Gas?
Dry Dry gas is a very helpful fuel additive that is used to remove water from gasoline and prevent water-contaminated gasoline from freezing. While the solution itself is actually called dry gas, there is one brand of this fluid named...
The Best Used Cars to Buy If You’re a Wedding Planner
As As a wedding planner, the demands placed on your time are going to be significant, even if you’re only dealing with one or two couples. You need to be a master juggler when it comes to your time and...
Symptoms of a Bad or Failing Fuel Pump Shut Off Switch
The switch may have tripped and must be reset if your engine suddenly stops while driving, has issues starting up, or turns over without starting.