Skip the auto shop - Our mechanics make house calls

Q: Car stalls at idle and fails to restart - 1993 Buick Century

asked by on

The car intermittently stalls at idle, and can fail to restart after this. Trying again after results in slow cranking, but nothing else. Sometimes it will start an hour later, sometimes not. It can stall upon placing in drive, and usually sputters so if I keep RPMs high, then ok. Check engine lights have never come on until recent. I'm getting a low voltage to the TPS code. I have replaced CKP sensor, ICM, and MAF. New battery, new fuel filter, the alternator and starter test fine. Replaced spark plugs and their wires. The car gets spark when it won't start. Throttle body and fuel injection cleaning as well. I've detached the Torque converter, but still stalled.

Could this be all from TPS or bad ECM ?

My car has 73000 miles.
My car has an automatic transmission.

A: Hello and thank you for contacting YourMech...

Hello and thank you for contacting YourMechanic. The TPS (Throttle Position Sensor) could be a large part of the issue you are having. If there is low voltage to the the TPS, check the harness with the key on and engine off for a 5 volt reference to the TPS harness. If there is 4.5 volts or less, then the ECM has a possible fault. Remove the harness from the ECM and turn on the key with the engine off and see if there is a 5 volt reference to the pin for the TPS harness. If there is a 5 volt reference, then the harness has resistance on that circuit and needs to be replaced. If the reference is 4.5 or less, then the ECM needs to be replaced. If you need assistance troubleshooting the TPS signal, a certified professional from YourMechanic can come to your car's location to assist with diagnosis and repair of the stalling problem.

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・Save up to 30%

Get a quote

What others are asking

Q: Sensor under intake manifold

Hi there, thanks for writing in about your 1993 Honda Civic del Sol. Your friend was probably referring to a failed MAP sensor. It does reside under the intake manifold and can cause mixture issues resulting in RPM surges. One...

Q: Power steering

Hello, the whining noise the old pump had is aeration usually from low fluid level that will damage the pump, that means there is a leak of fluid. This system is a closed type system no leaks allowed. First check...

Q: Grinding noise and overheating while driving.

It could be that the grinding noise you were hearing was the water pump bearings. Engine overheating can do extensive damage to your engine. I suggest you have a trained mechanic, such as one from YourMechanic, diagnose or repair your...

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...
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...
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...