Q: My 1999 Chevrolet Silverado
with a 5.3-liter engine and 146,000 miles starts fine in the morning, but when I accelerate, the engine loses power and backfires. As I continue to drive, all the kinks work out and it runs normally. I took the truck to a mechanic who didn’t find anything wrong, but speculated that the fuel pump was failing. A few months later the fuel pump did fail. He replaced the pump and fuel filter. He also cleaned the fuel injectors. Since the repair, the truck runs fine except in the morning. Any ideas? J., e-mail
A: The backfiring may be cured by having the engine computer reprogrammed. Ask your favorite technician to consider this procedure. It’s also possible that the throttle body unit and mass air flow sensors are dirty. If this is true, a thorough cleaning may cure the condition at least until the next time these parts are impaired by dirt, grime and deposits.
No taillights
Q:The taillights, including the third brake lamp in the rear window, quit working in my 1999 Chevrolet Cavalier. What do you think is wrong? G.C., e-mail
A: The first place to look is in the fuse panel. It’s likely the fuse to the rear lights has blown. If so, this could be an isolated incident of a fuse blowing for no apparent reason, or perhaps there is a short in the tail lamp circuit. Check the fuses. If indeed the fuse to the taillights has blown, replace it. Once a new fuse is installed, the lights may work fine. If they illuminate and then go out, check the fuse again. If it has blown, there is a short in the circuit. A short could be caused by a water entering a tail lamp assembly or frayed insulation of the wires going to the taillights. Perhaps corrosion is wreaking havoc to one or more light sockets in the circuit.
Check the computer
software
Q:About six months ago I purchased a 2001 BMW 540i with 33,000 miles. It now has 36,000 miles. In the past two weeks the engine has stalled twice. The stalling occurred when slowing to make a turn into a parking lot. When it stalled, it started right up. I brought the car to a BMW dealership where a technician connected diagnostic equipment, but no problems were found. He drove the car for four days, but the stalling never occurred. As a result, I brought the car home. This worries me as my wife is the primary driver. I don’t want the car to stall when she is driving. I drove the car for a week and it never stalled for me. Any ideas what’s wrong? K., e-mail
A: Normally when there is a problem, the engine computer illuminates the check engine light. This sort of a problem should store a trouble code in the computer for a technician to download with his diagnostic equipment. In your case, this didn’t happen. Since this is suspicious, it’s possible the computer needs to be reprogrammed. Perhaps there is a software glitch. It’s also possible the throttle body or the mass air flow sensor is impaired by deposits, grime or dirt. If so, cleaning may cure the trouble.
Normally, when turning a vehicle, the computer-controlled engine idle is bumped up a little to prevent stalling. There are sensors that monitor the steering system that tell the computer that the driver is turning. If a sensor fails, the check engine light illuminates. This doesn’t seem to be happing in your vehicle. The computer software might be the first place for a technician to look for corrosion on the electrical terminals, a loose pin connector or reprogramming.
Not-so-hot van
Q: The heater in my 1985 G20 conversion van is acting weird. When I place the controls to heat, vent or defrost the blower runs continuously but the heat turns on and off.The thermostat and antifreeze were replaced in 2004. What could be wrong? L.F., e-mail
A:Check the coolant level. There may be a leak in the engine cooling system. A lack of hot engine coolant to the heating system can cause the condition you describe. If the coolant level is low fill the radiator and coolant reservoir with a mixture of water and antifreeze that protects against freezing to about minus 35 degrees Fahrenheit. Also, check the system for leaks. Repair leaks as needed.
It’s also possible that there is a water flow valve connected to a heater hose that controls coolant flow to the heater. The valve may have a fault or the vacuum line that connects to the valve has a leak. If the valve has a fault, replace it. If a vacuum line is leaking replace it, too.In addition to all of this it’s possible the heater core in the ductwork is blocked. If this is the case, replacement is the cure.
Overdrive Engages With A Thump
Q: When driving my 2001 Ford Escape at highway speeds the automatic transmission constantly shifts in and out of overdrive. When overdrive engages it does so with a thump. Then it engages and disengages with the slightest change in acceleration.I took the vehicle to my transmission shop where no trouble codes were found in the computer. The technician doesn’t know what to do. This is a real pain to drive. Do you have any suggestions? G.F.N., e-mail
A: Junk it. I’m just kidding. The fact that the computer hasn’t stored any trouble codes makes it almost impossible for a technician to determine what is causing the condition. Also, the computer doesn’t think anything is operating out of programmed specifications. Any suggestion by a technician would be a guess.
The overdrive as you probably know is controlled by the computer. It monitors the load on the transmission and determines when overdrive should engage and disengage.
Vehicle speed and vehicle load play an important part in the computer’s logic when to lock overdrive and when to disengage. The faster you drive the more often the overdrive engages and disengages. After all the faster you drive the more air resistance there is on the vehicle. This increases the load on the transmission.
Since there doesn’t appear to be any major problem causing this annoyance there isn’t a repair, but you might consider these options. Sometimes changing the transmission fluid changes transmission shift characteristics. A transmission flush may soften overdrive engagement.
It’s also possible there is a software update for the computer that might reduce your concerns. Ask the transmission shop technician to check.
In the meantime there are a few things you might do. If you carry a load in your vehicle reduce it to only the essentials. Make sure the tires are properly inflated. If you are a speedster on the highway slow down. Also, try using the cruise control as much as possible when conditions are safe to do so.
Check Coolant Level Sensor
Q: During a recent oil change a technician advised that the coolant level in my 2002 Chevrolet Impala with 50,000 miles was low. I later added coolant to the proper mark and monitored the level. When the coolant level dropped again I replaced the radiator cap.
After three months the coolant level remains at the proper level but the low coolant indicator light periodically turns on. It usually turns off after a block or two of travel. The coolant level is perfectly fine and the engine temperature is normal. What’s up with the low coolant light? T.M., Roseville, Minn.
A: Your Impala is winking at you. This doesn’t appear to be anything serious. Check the coolant level in the morning before you take off for the day. It might be a little low. If needed add an antifreeze and water mix to protect against freezing to about 40 or 45 below zero for your area. This should turn off the light until the next time the level drops.
If the light continues to blink a sensor in the coolant recovery tank probably has deposits on it. If you are a do-it-yourselfer, remove the sensor and clean it with soap and water.
Deposits on the sensor is an indication that the coolant in the system is in need of a change. A thorough flush may be in order. Consider taking the car to a repair shop for this service as an improper flush may cause conditions within the engine that can be extremely corrosive to metal and gaskets within.
Brakes
Q: Recently I had the brakes replaced in my 2000 Chevrolet Silverado with 39,000 miles. I have been complaining to General Motors about having to use excessive force on the brake pedal to stop the truck. My son who has been working on race cars for many years replaced the rotors and brake pads. He found one rear inside brake pad was completely worn out. After his repair the brakes are excellent.I checked on the Internet and learned that Silverados have brake problems. I found a recall for the rotors. I called General Motors about this because I never received a recall notice. After hours on the phone I was told that because I didn’t have the work performed at a General Motors dealer that they wouldn’t offer any assistance. There isn’t a dealer in my area. Is this why there are more Toyotas on the road today? V.O., Grantsburg, Wis.
A: Perhaps Toyota’s perceived reputation has something to do with high sales of their products. Be this as it may, all companies even Toyota have policies that customers and employees must follow. If not an employee can be terminated and customers don’t always receive what they are seeking.
Incidentally, a quick check of recalls didn’t reveal a recall for brake rotors.
There might be recalls and technical service bulletins that do address brake problems specific to your truck but no recalls of brake rotors. One technical service bulletin does address excessive premature wear of rear inner brake pads that explains the installation of additional parts to help prevent the accumulation of road dirt and debris that can impair caliper and brake pad movement.
As for your phone conversation with a General Motors representative, it’s likely the person you spoke with on the phone was following company policy. You might consider gathering dealer repair invoices that show that at some time you went to a General Motors dealer to have the excessive force brake concern corrected.
Also, gather receipts for the recently installed rotors and other replacement parts. With copies of receipts and a nice letter to General Motors asking for assistance you might receive whatever it is you seek. If it’s a refund for the brake rotors or for all the newly installed parts make sure you explain what happened on the phone, explain the situation about the information you read on the Internet and that there isn’t a dealer in your area. Who knows you might receive something toward the brake repair.
Vibration And Speedometer Raise Suspicion
Q: My wife drives a 2001 Hyundai Elantra with 119,000 miles. There is a vibration in the front-end above 45 mph. The front-end was checked but no problems were found. A dealer parts department person suggested that the vibration might be caused by the tires.
Recently the car was in for an oil change. When the car went into the garage it had 115,000 miles on the odometer and when it came out it had 119,000 miles on it. It’s as if someone messed with the odometer. When I ask the dealer service manager about this he said that to correct the trouble would be an expensive repair.
In addition to all of this when it is cold outside the engine hesitates upon starting and when driving. I poured an additive into the fuel tank and this seems to help.Should I buy a new car? What should I buy? What do you suggest about these problems? R.M., e-mail
A: Never fear Dr. Gizmo is here. The vibration could indeed be caused by tires that are out of balance or have excessive run-out. If they are not out of round balancing should cure the trouble.
As for the odometer problem, it’s highly unlikely that the odometer jumped 4,000 miles during the oil change.
However, to fix the trouble is expensive and at the very least would require replacement of the speedometer head and odometer. Wait a while and see if it jumps again.
As for the hesitation, a thorough cleaning of the throttle body or mass air flow sensor units might cure the condition until the next time deposits impair the parts.
As for the purchase of a new car, there are so many good vehicles consider doing a little research on the Internet at the various manufacture and consumer web sites to narrow the field to a few vehicles. Consider another Hyundai.
Once you have done this, test drive the cars on your list to determine which car meets your needs. Of course if you decide to purchase a used vehicle take it to a qualified technician at an independent repair shop or another dealer for an unbiased examination before you commit to a purchase.
Need Heat
Q: The heater in my 1996 Chrysler Cirrus doesn’t heat very well. When the temperature is near zero the windows defrost very slowly and my feet get cold.To fix the trouble I have had the radiator and heater core flushed. Also, the thermostat has been changed. I’m beginning to wonder if this car just doesn’t have good heater.Do you have any suggestions? B.T., e-mail
A: On a frigid day it may take 10 miles of travel before the engine reaches full operating temperature. Once it does the heater should produce plenty of heat.
Technicians normally take temperature readings at the center dash vent with the heater blower and temperature set on high. I’ve seen temperatures as high as 150 degrees. If you have a baking thermometer set the heater controls to high heat and high blower. Place the thermometer in the center vent. Once the engine warms to full operating temperature check the vent temperature. Drive the vehicle to make sure it heats to full operating temperature. You may be surprised at how hot the air blowing from the vent really is. However, if the temperature is not 110 degrees or higher there is work to be done. It’s possible that the thermostat is not functioning as designed. It might be opening too soon. Perhaps the water flow valve in the system isn’t opening all the way. This reduces the volume of hot engine coolant to the heater. Maybe the heater core has restrictions. Just maybe the diverter doors in the ducts aren’t functioning as designed. An experienced technician can verify any of these conditions. If so replacement of the faulty part should cure the trouble so you are as warm as toast.
Cruise Not Cruising
Q: The cruise control in my 1990 Buick LeSabre is not working. I replaced the switch but this did not cure the trouble.When I engage the cruise control the light on the dash illuminates but it doesn’t hold a steady speed. What else can I do? J.B., e-mail
A: If everything else in the car is working as designed it’s likely the cruise control servo unit has a fault. Tests can verify a fault.
Before you take the vehicle to a technician for testing you might be able to do some investigation at home. If you have a repair manual follow the procedures for adjusting the linkage. Also, you can check the diaphragm in the servo for vacuum leaks if you have a vacuum pump. Also, check the electrical connections for security and corrosion. Correct electrical connection impairments as needed.If the linkage is in proper adjustment, vacuum is steady and external electrical connections are fine it is more likely than not that the servo has an internal fault. If this is found to be true replacement is the cure.
Substandard Brake Repairs
Q: Recently I had the front brakes replaced on my 1996 Dodge Dakota SS Magnum. Since the repair when I apply the brakes even at low speeds the left front tire squeals. Is it braking before the brakes on the other wheels? Is this caused by a faulty caliper? G.R., San Angelo, Texas
A: This should not be occurring. Take the vehicle back to the shop that repaired the brakes. The trouble could be the result of shoddy work or perhaps a stuck caliper. It’s also possible that the tires are not properly inflated. In any case return to the repair shop.The technician who did the work should not have released the vehicle to you with this condition. If he test drove the vehicle after doing the work he would have discovered the trouble. If he did discover this problem before releasing the vehicle, he should have explained the trouble to you. He also should have told you what it would take to repair it.
If he did tell you and you didn’t authorize the work, shame on you. This problem causes unequal braking and could impair your ability to control the vehicle in an emergency. Have this corrected right away.Recheck
Repair Work
Q: Recently I replaced the water pump in my 1994 Nissan Maxima. Now there is a bad water leak that appears to be from the thermostat housing. Where do you think it is leaking? J.D.J., e-mail
A: On your vehicle there is a cover that hides the thermostat housing and water pump. The thermostat and water pump are in close proximity to each other with the thermostat housing located just above and to one side of the water pump. If the thermostat housing wasn’t leaking before the water pump replacement and it wasn’t removed during the water pump replacement operation then the leak is probably from the water pump. However, it is likely you removed the thermostat housing. If this is the case it’s possible the gaskets were not aligned during installation. As a result there is a profuse leak.
Recheck your work. Replace parts as needed.
Phil Arendt is an automotive
columnist, consultant and
ASE-certified master technician.
E-mail him on the Web at
www.drgizmo.ws.