Engine Stall May Have Electronic Cause

Times Staff Writer

Question: I have a 1980 Lincoln Continental Mark VI that will cut off without any warning after about 25 minutes of driving. If I wait for about a half hour, it will start again and run for another 20 to 25 minutes. Then it stalls again. I have a variable Venturi carburetor. Is there any other carburetor that I can put on the car? I have had the carburetor rebuilt.--H.W.

Answer: It may not be the carburetor or the fuel system that is your problem. The behavior you describe also resembles an ignition or electronics problem. Your 302-cubic-inch engine has what is known as an EC3 electronic control, which operates the engine. The control box, for example, relies on a crankshaft position sensor to control such important things as the timing of the electrical impulses to the spark plugs and the idle speed.

The computer and its various sensors are quite sensitive to engine conditions. Under certain conditions, such as when the system detects an overheating situation, the computer will automatically shut down the engine, according to Ford technicians. The problem is complicated enough that you need a top-notch mechanic to diagnose and fix the problem.

Q: I have a 1988 Camry 4-door sedan that has a problem with creaking and groaning from the front end. A Toyota dealer recently lubricated the front suspension, but the mechanics warned me that the problem would recur the first time it rained. I took the car to another dealer, who said they could correct the problem by lubricating the sway bar bushings. Because I have conflicting statements, I am wondering if there is a definite problem with the model.--B.M.N.

A: In April, 1988, Toyota issued a service bulletin to dealers that addressed the problem you raised about your creaking front end. The bulletin advised that you could solve the problem by replacing a washer on the lower control arm.

A control arm is an assembly that connects the car's stationary frame to the wheel and allows the wheel to pivot up and down when there are irregularities in the road surface. The wheel is connected to the control arm at the ball joints, which allows the wheel to turn as well as pivot up and down.

The washer that needs to be replaced is called a "cushion retainer" and is treated with a molybdenum sulfide coating that is supposed to allow things to operate more smoothly.

The repair is covered under warranty, but if your warranty has expired you might bring the service bulletin to the attention of your dealer and negotiate for the repair to be covered at Toyota's expense.

Q: In the past year, you have on many occasions commented on the use of gasoline for older vehicles and the phase-out of lead in regular gasoline. My question has to do with premature wear of the valve seats on my 1971 Ford LTD. The 400-cubic-inch engine had a valve job about 60,000 miles ago. My question is whether the valve seats were replaced with the type made of hardened metal so that I can now safely use unleaded gasoline. So far, I have not detected any loss of compression.--C.L.T.

A: The hardened valve seats became original equipment in Ford vehicles when unleaded gasoline and catalytic converters were introduced to reduce engine pollutants. The converters need unleaded fuel to remain effective.

Ford did not start using catalytic converters until the 1975 model year, so your 1971 did not have a catalytic converter. That means it was almost certainly not equipped with the hardened valve seats needed to burn unleaded gas, according to Ford technical experts.

As a result, it is unlikely that the replacement seats were made of hardened metal, especially if they were original replacement parts from Ford. In any event, the use of leaded regular gas, even though its lead content is reduced, should not have a dramatic effect on your valve wear, according to fuel experts.

If you are still concerned, however, you may want to add a small amount of gasoline additive that simulates lead. These additives are widely available at auto parts stores.

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