Ask Dr. Gizmo
By Phil Arendt
Engine should have zip when accelerating
Q: My 1991 Mercury Capri with 15,000 miles is in perfect condition but the engine hesitates. When the transmission is in neutral, the engine revs up without any problem. Once it is in gear, the engine hesitates and will not accelerate. It does not backfire. It just will not accelerate. I replaced the spark plugs, distributor, distributor cap, air filter, and rotary button all is vain. What is your advice? --J.G., E-mail.
A: The engine should have some zip when punching the gas pedal. Since it lacks acceleration, it is possible the engine thermostat is not functioning normally. This keeps the coolant temperature lower than specifications and the computer does not receive proper information. Consider flushing the engine coolant system if it has been a long time since it was flushed. Also, replace the thermostat. Once this is accomplished, according to a factory technical service bulletin, engine performance should return to normal.
Q: While I was driving my 2000 Lincoln LS in a recent heavy snowstorm, the rear wheels were spinning and the car would not move unless I kept the engine speed up around 3,000 rpm. After a few times of doing this, the check engine light turned on and the engine had no power. Could the spark plugs be giving up? L.Y., E-mail.
A: Yes, the spark plugs may be failing. To find out for sure what is causing the condition, ask a technician to run diagnostic tests. He will check the engine computer for diagnostic trouble codes that may verify that the spark plugs are failing. If this turns out to be true, replacing the plugs will cure the trouble.
It is also possible the ignition coils are failing or a mechanical problem is causing the cylinders to misfire. Let us hope new spark plugs cure the condition.
Q: There is a tapping sound coming from the glove compartment in my 2004 Jeep Cherokee Limited with 43,000 miles. I hear the sound for about 30 seconds after turning off the engine. My dealer shop mechanic diagnosed the trouble as a faulty valve door on the air conditioner. They want $1,300 to fix it. Does this sound right?- - D.L.B., Naples, Fla.
A: It is likely a diverter door assembly is knocking in the HVAC system. The door directs air to the dash, floor and defroster vents. Unfortunately, the door is operated by an impaired servo. The parts are not serviceable separately. It is part of a subassembly. Chrysler issued a technical service bulletin that states that when something fails, replace the entire subassembly.
This takes several hours of labor and the subassembly is not cheap. If you can live with the condition do not have it repaired, but $1,300
sounds about right.
Q: I have a 2001 Jeep Cherokee with a 6-cylinder engine in excellent condition despite having 138,000 miles on the odometer. It has had excellent care. Unfortunately, the gas mileage is terrible. My Jeep only gets 11 miles per gallon. What can I do to get better gas mileage? -- M.S., Plainfield, Pa.
A: Consider replacing the thermostat. The engine relies upon heat to burn fuel efficiently. If the engine’s cooling system thermostat is not up to par, fuel economy suffers. Installation of a new thermostat could increase heat in the engine and fuel economy.
In addition to replacing the thermostat, make sure cold tire inflation pressure is according to manufacturer recommendations. If there is wear on the outside edges of the tires, the tires are suffering from under-inflation wear. Under-inflated and overinflated tires reduce fuel economy.
Also, make sure the engine is tuned, the engine oil is fresh and clean. Replace the air filter if it is dirty, curtail short errand runs by combining several errands and avoid aggressive driving.
Q: Recently the CD player in my radio quit working in my 2002 GMC Envoy. Rather than purchase a new radio from a dealer I bought the exact radio from a party at an internet auction. When I installed the radio, it was locked. I learned from the online auction that I need to input a code into the radio for it to work. I received some codes I found on the internet but I have no way to input them. What do you suggest? -- LT., E-mail.
A: The trouble you are encountering is a security feature that helps prevent radio theft. Once a radio is removed from a vehicle, it will not work in another vehicle until it is programmed with a code. Consider taking the vehicle and radio to a GMC dealership. A technician will connect a computer to the radio via your vehicle. He will program a code into the system so the radio will once again deliver sweet music.
Phil Arendt is a columnist, consultant and A.S.E. certified master technician. Readers may send questions to Dr. Gizmo at P.O. Box 548, Cary, IL., 60013 or his e-mail box drgizmo@drgizmo.ws
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