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Ford Taurus 99 engine stalls halfway on the road

I have this weird problem that the car suddenly stops running while on the road. It has happened 3 times in the past 14 months. Every time it happened, my speed was less than 10 mph in slow traffic. And it was after I had driven over 15 minutes on the highway without any signs of trouble. The check engine light and low engine oil light would come on while the stall happened. After the stall, the car would not start. But after 20 minutes or so, the car would start normally, and it would run without any problem for months.

I have brought the car to a mechanic to diagnose the problem. I was told that it might have been caused by a faulty exhaust valve. The valve was replaced 5 months ago, but the stall happened again earlier this week. About a month ago the starter died and I went to a different shop to replace it. I was told that the cover gasket was leaky but it should not cause noticeable problem. After the starter replacement, I also started to notice that the car would occasionally vibrate abnormally for about 30 seconds after starting. I am not sure whether this is related to the stalling problem.

I cannot tell whether it is an engine problem or an electrical problem that is causing the engine to stall. I would greatly appreciate it if you can point out what tests I should run to pinpoint the problem.


“Faulty exhaust valve?”

Really? Just one?

Replacement of an exhaust valve would require disassembling part of the engine, and would cost a LOT of money. It’s hard to believe that one of the exhaust valves was actually replaced.

Perhaps you misunderstood the description of whatever the mechanic did, or perhaps they told you some BS and replaced something else. Hard to tell from here.

You don’t have a regular mechanic, to which you’ve taken the car in the past, do you?

Too bad. Maybe now is a good time to start a business relationship with a good independent mechanic. Then you’ll know where to take the car when a problem arises.

I’d like to hear an explanation of the exhaust valve thing. One faulty valve will not cause the car to quit but it will run rough.

It sounds to me like there is a lot of misinterpretation going on as to what was wrong and what was done.

Based on the scant info and if it’s assumed there are no codes present I’d say the fuel pump is dying. That can be an intermittent problem with the symptoms you describe and could also be behind the vibration after starting. (That would be due to lack of residual fuel pressure and the pump is trying to burp the air out of the fuel lines.)

A large number of car issues are the result of simply ignoring basic maintenance. How old are your plugs & wires? Fuel & air filters? Is the engine light on? Do you tend to ignore such things. How many miles are on this engine?

I would probably do 2 things. One is, as ok4450 implied, to get a fuel pressure gauge on it & make sure the pressure is tested under load. Although I’d not suspect that to show up only at slower speeds it is a very simple & very basic thing to do. The second thing is to have the spark plugs inspected and while they are being inspected have a compression test run. I don’t know if that would be among my first thoughts normally, but there is this exhaust valve mystery.

Thanks a lot guys. Apparently I am very car challenged. I’ve found my receipt and what they replaced were a canister solenoid valve and an oil pressure switch. The engine light has been on and off for almost 3 years. The code was always small leak. It almost always went away by itself, and I was told that it might be caused by a loosen gas cap. The light was on when the stall happened in March. They tried to fix it by changing the valve and the switch. But the light came back on again later. I was so tired of it so I bought a code reader to clear the code by myself.

Any new thoughts? I feel embarrassed for being so ignorant. But I hope you guys don’t mind enlighten me a little bit. Thanks a bunch!

The problem might be with a heat sensitive crankshaft position sensor. This sensor sends a signal to the computer if the crankshaft is rotating or not. If the sensor fails where the computer no longer see’s crankshaft rotation the computer shuts down the ignition and fuel system and the engine stalls. Once the sensor cools back down the computer recieves the signal again and the engine runs.

Most of these crankshaft position sensors are made from plastic, so over time heat distorts the plastic causing problems with internal circuit of the sensor. One way to test these sensors is unplug the connector and take a resistance reading while applying heat to the sensor with a heat gun.