Hamilton Journal-News

Q: My 1999 Chrysler 300M with 126,000 miles quit running. A mechanic diagnosed the trouble as failed cam and crankshaft sensors. Is this caused by old age? What would cause both sensors to fail? Is the mechanic pulling my leg? B.H., e-mail

A:The failure is likely due to time and mileage. It is unusual for both sensors to fail at the same time, but I’ve been in this business a long time, and anything is possible. Individual tests of the sensors would verify if both or one of the sensors failed. Once testing is completed, you will know if the mechanic is giving you the runaround.

It is possible that both sensors share a wire harness. As a result, both sensors might need replacement at the same time — even if only one has failed. It’s also possible that there is a fault in the wire harness to the sensors. There might be a loose connection, corrosion or a loose pin in a plug. If the sensors do not have a fault, probing the circuit related to the sensors is in order.

Vehicle storage stirs debate

Q:I have a Corvette that I store every winter. I have received two different opinions as to the proper way to store the car. One opinion is to add a fuel stabilizer to the gas tank, then drain it as low as possible and remove the battery to minimize the risk of a fire. The other opinion is to fill the gas tank, add a fuel stabilizer and place a trickle charger on the battery. What do you suggest? B.D., Woodbury , Minn.

A:This will give you more to consider. You might know the old saying, “If you don’t use it, you lose it.” Fill the gas tank, make sure there is a fresh supply of oil in the engine, disconnect the battery cables and place a trickle charger on it. About once a month, on a nice dry winter day, make sure the tires have proper inflation, connect the battery and take the car for a drive. A 10-mile drive should bring the engine to full operating temperature to remove moisture and other contamination in the drivetrain.

The seals in the drivetrain will remain lubricated to help prevent future leaks, and the brakes won’t suffer from corrosion damage. On top of all of this, the likelihood of the engine suffering from fuel system ailments will be greatly reduced.

Smoke can find a leak

Q:The check engine light is on in my 1998 Ford Ranger with 47,000 miles. I checked for trouble codes and found codes PO171 and PO174. These codes indicate a lean running condition. I erase the codes, but it isn’t long before the check engine light turns on again. I checked the air filter, fuel filter, fuel pressure regulator, fuel injectors and fuel pump. They check out fine.

Also, the mass airflow sensor appears to be very clean and unobstructed. All sensor connections are clean and sound. All hoses and tubing are firmly connected and sound. I’ve narrowed down the cause to a vacuum leak or air leak.

What is the best way to search for a vacuum leak? Should I probe using Freon or propane? Will the computer mask these methods? Or, should I use a stethoscope? D.F., Hampshire, Ill.

A:You are on track to replacing the plenum gaskets and seals. Also, the exhaust manifolds could have a leak. Let’s apply the brakes before you do unnecessary work. You could use throttle body cleaner to check for leaks, but the best method is smoke. Technicians often use a smoke machine to detect vacuum and air leaks at the exhaust manifolds, intake plenum, vacuum lines and fuel evaporative system. Since it’s likely you don’t own a diagnostic smoke machine, you may find a leak using throttle body cleaner. However, your description of the trouble appears to be derived by a malfunctioning mass airflow sensor. You might consider cleaning the unit even though it appears clean. If the symptoms don’t cease further testing of the unit should verify a malfunction. If so, replacement should be the cure.

Also, it’s possible carbon deposits in the engine are causing conditions that appear to trigger the computer to run the engine lean. Consider adding a carbon cleaner additive to the fuel tank. This might resolve the condition.

Lack Of Fuel Impairs Engine Starts

Q:Three years ago I purchased my 1995 GMC. It now has 164,000 miles on it. It has a 4.3 liter V-6 engine that is not the factory original. It has been running great until recently. For the past 30 days the engine is difficult to start. The battery is good and the starter cranks without trouble. The trouble is the engine just won’t start.

To start the engine I give it a shot of starting fluid. One squirt is all it takes. Once the engine is running I can shut it off and it will start fine the remainder of the day.

Since the engine is not the original I can’t follow self-diagnostic test procedures. As I’m a do-it-yourselfer I tested individual sensors according to repair manual procedures. They all check fine. I also replaced the fuel filter and spark plugs, but this didn’t solve the trouble.

It appears that there isn’t any fuel to the injectors. Could this be a powertrain control module problem? D.M., Virginia Beach, Va.

A:You have been thorough in your quest to find the trouble and repair it. Don’t give up you will find the cause of the condition. You are on the right track. A lack of fuel is likely.

Check the fuel pressure. The 4.3-liter engine fuel pressure regulator and hoses have a tendency to develop leaks. Sometimes leaks become so prevalent that fuel contaminates the engine oil.

Sniff the engine oil. Your nose might detect gasoline. If so check for fuel pressure regulator leaks. You’ll find test procedures in your repair manual. If this is the cause replacing the regulator is the cure. Also, change the engine oil and filter so engine bearings aren’t damaged due to gasoline contaminated oil.

Technician Follows Diagnostic Equipment Prompts

Q:There is a nagging starting problem in my 2000 Oldsmobile Intrigue with 56,000 miles. For the past three years occasionally the engine is difficult to start. When this occurs I turn the ignition key, the engine cranks and wants to start, but it doesn’t. Then I shut off the key and try again. Usually on the second try it starts right up but there have been times when I have to go through the routine 15 times before the engine starts. By then there is a strong gasoline odor. When the engine does start it runs fine. This trouble occurs once or twice a week. Other than this issue the car is fine and drives as it did when it was new.

Given that this is an intermittent problem I fear that if I take the car to a mechanic I will end up paying for his education. However, I don’t like being stranded either. What’s your advice? G.N., Dayton, Ohio.

A:Trade it in. Of course I’m just kidding. Your car can be fixed. This might simply be caused by a dirty mass airflow sensor or throttle body. A thorough cleaning might do the trick.

Take the car to an experienced A.S.E.-certified technician. He will scan the computer for trouble codes. This likely will lead him to the source of the trouble.

The self-diagnostic capabilities of your car are very sophisticated. The test equipment used by an experienced technician also is very sophisticated. The diagnostic tool basically communicates with the car’s computer, performs a series of tests that checks sensors and the computer for variances from factory specifications. The equipment prompts a technician through the procedure and tells him where to look for the cause of the trouble.

Sensors such as the mass air flow sensor measure air temperature, barometric pressure, air volume and more. Dirt impairs proper function. If tests find the airflow sensor is not up to par cleaning might revive the part.

It’s also possible that this is caused by a faulty throttle position sensor, crankshaft sensor, camshaft sensor or oxygen sensor. If this is true, tests will verify a fault. Replacement will end your woes.

Broken Clock Spring Disables Air Bags

Q:It’s a pleasure to read your section in the newspaper. The horn and cruise control don’t work in my 1997 Town and Country van. Also, the air bag light is on. I tried to fix the trouble by replacing the fuses, but this didn’t cure the problem.

A friend told me that the cause of the problem is inside the steering wheel. Can you help? M.M., Austin, Minn.

A:It’s my pleasure to help you. From your description of the trouble there may be more than one problem. There is a part named a clock spring in the steering column that might be broken. This will disable the air bags and horn. The repair involves replacement of the part. This requires disassembly of the steering wheel, but there is good news. Many vehicles with this problem were recalled. Contact a dealer. Your vehicle may qualify for this repair under the recall. If so you won’t have to pay for this repair.

As for the cruise control, the multifunction switch should be tested for faults. It’s possible it needs replacement. There also other parts in the cruise control that might have failed but the multifunction switch is the number one suspect. Testing might verify failure. If so the steering column covers need removal to replace the part. You might as well have this cured when the clock spring is replaced.

Leak In Evaporative Vapor System

Q:I purchased my 1998 Acura Integra when it was new. It now has 157,000 miles and has never given me trouble except for the last four years the check engine light has been on. Four times technicians have checked out the problem. Twice after paying a diagnostic fee a technician said that he didn’t know what is wrong. One said that it was a problem with a purge solenoid which he replaced to no avail. After several follow up visits I quit going to the shop as I was frustrated.

In order for my car to pass the state emission test I have the computer reset, but once I drive 40 miles the light turns back on. Is this a computer problem? B.P., e-mail

A:This likely is the result of a leak in the evaporative emissions system. Your vehicle processes gasoline vapors in a closed system so gasoline vapors don’t escape into the atmosphere. A leak in this system can cause the check engine light to illuminate. This can be caused by a faulty solenoid, loose gas cap, fueling the car when the engine is running or by a small leak somewhere in the system as a result of a failed seal or hose.

Often leaks are difficult and time consuming to find. Because of this not all shops have the equipment to pinpoint a leak. You might find an independent shop has the equipment and manpower to determine the cause, but more than likely a dealer has the diagnostic equipment and a talented technician to tackle this problem.

Once a leak is found repair may take only a few minutes or it may entail removal of the gas tank which requires more time. The cost of diagnosis and repair for this type of problem can be expensive, but depending upon the environmental laws in your state you might have to have this problem repaired for the vehicle to comply with the law.

Parasitic Discharge Is Normal

Q:I believe that few weeks ago you addressed a parasite current drain on newer cars that results in a battery failure. If I’m right about this is there any way I can access the article on the internet? R.L., e-mail

A:It’s been a while since the question and answer you mention was in the newspaper. You can read past Dr. Gizmo columns on the internet on the Dr. Gizmo website at www.drgizmo.ws. There is a calendar feature that posts columns on Mondays. Current columns that appear in the newspaper do not appear on the web site for a couple of months. If you want the latest columns read the newspaper or visit newspaper web sites to access the column.

As for parasitic discharge, the computers in modern vehicles require small amounts of electrical power. Over a period of vehicle non-use or if the vehicle is driven short distances the power draw can drain the battery to the point the engine won’t start. The length of time before a battery discharges depends on ambient temperature, the complexity and equipment on the vehicle, the age of the battery and how the vehicle is used. There is no repair for this as this is a normal electrical load on the battery.

There are conditions that can be abnormal. If electrical equipment power draw exceeds factory specifications there is a fault in the system. This could be caused by a variety of factors but a technician can test the system to determine what is causing the excessive power draw and replace the part that is using too much power.

In many instances aftermarket equipment such as cell phones, mp3 players, DVD players, aftermarket radio equipment, radar detectors and other devices draw power from the battery so it’s important to disconnect devices such as these when the vehicle is not in use.

Since a parasitic discharge can also be the result of a dirty battery it’s important to keep it clean. To do this you can purchase cleaning chemicals available at most auto supply stores. Just follow the directions on the product. You can also use soap and water or a baking soda and water solution and a soft plastic brush to remove the acidic grime that often develops on the battery case.

Stuck In Overdrive

Q:The overdrive light in my 1999 Nissan Frontier with a 4-cylinder engine stays on but the overdrive in the transmission is engaged. I don’t mind driving the vehicle all the time when it is in overdrive but I fear this is harming the vehicle.

Is this something I should be concerned about? What would cause the light to constantly be on? W.S., West Chester, Ohio.

A:Operating overdrive full-time is not harmful to the vehicle. The transmission is designed to engage overdrive when cruising. However, if you drive with heavy loads such as pulling a trailer or driving on steep grades the overdrive feature should be turned off. This is to prevent the transmission from overheating and provide engine braking when driving in hilly terrain. Since you can’t disengage the feature by taping the button avoid these conditions.

The trouble might be the result of a sticky valve inside the transmission. A transmission flush might cure the trouble. It’s also possible there is a faulty connection in the circuit that controls the overdrive function. Testing by a certified technician should be able to determine the cause and suggest a lasting cure.

 

 

 

Phil Arendt is an automotive columnist, consultant and

ASE-certified master technician.

E-mail him on the Web at

http://www.drgizmo.ws.