Dr. Gizmo Column

 Special Announcement: Big Brothers, Big Sisters

This week the column is shorter than usual because I’m doing something I haven’t done in probably 30 years. On February 24 I’m going bowling. This time it’s for something special and not to win a beer frame or bowl a perfect game. That would be a miracle! This time I’m helping Big Brothers Big Sisters of McHenry County on team “Master Bowlers”. None of us are Master Bowlers but we believe helping a child makes a big impact on him or her. Help can make a change that ripples through a family, school, and more importantly, throughout our community. I hope you'll join me in my efforts to give a child the resources he or she needs to be successful. Please open up your automotive hearts and put off that purchase of an upgraded stereo, racing wheels or GPS for one week. Your donation of whatever amount you feel is right can start a child on the path to academic achievement. Please type this link or click https://www.kintera.org/faf/donorReg/donorPledge.asp?ievent=1044474&supId=375133209 in your browser to visit my personal donation page. Thank you!

"Dr. Gizmo"

By Phil Arendt

Computer Reset Often Cures Trouble

Question 1
The 4.0-liter engine in my 2004 Jeep Grand Cherokee Laredo idles rough and the check engine light is on.  This has been going on for about a month.  I took the vehicle to a repair shop where a technician replaced an oxygen sensor.  When I picked up the vehicle the check engine light was off but the engine still idled rough.  I drove about three blocks and the light turned back on.  I returned to the shop where the technician replaced another oxygen sensor and turned off the light.  When I returned the light was off but the engine did not run any better.  The technician told me to drive for a week and the engine should start to run better.  It didn’t but and the light remained off. 

I went to another repair shop.  I explained what had happened at the first repair shop.  A technician found a code that indicates that the engine computer is faulty.  After doing several tests and checks he does not think this is the trouble.  He does not want to install a new computer unless he is absolutely sure this is the cause.  So far he has checked the spark plugs, coils, fuel mixture, road tests and did a number or visual exams of wiring connections plus more but the code for the engine computer keeps popping up. 

I don’t want him to replace the computer if he is not sure it is the cause of the trouble.  What are your suggestions? R.H., email

Answer 1

I’m flattered by your request.  Also, it appears your technician is convinced the engine control module is not the cause of the rough idle condition and is not in parts replacement mode.  Sometimes resetting values in the engine control module cures unusual symptoms.  Since it appears your technician has the tools to do the work ask him to step back, take a breath and consider this suggestion.  It might resolve the issue.

Upset Over Fuel Consumption

Question 2
Doctor, I have a friend who is very unhappy with the mileage he is getting on his 2013 Escape. It’s 21 miles per gallon with lots of rural driving.  This brought up a question.  Who is responsible for calculating the mpg numbers that the manufacturers advertise?  S.L., email

Answer 2

Manufacturers have laboratories that are certified and monitored by the Environmental Protection Agency.   Tests are conducted by technicians and engineers employed by the carmaker under the watchful eyes of an EPA engineer.  Evaporative emissions such as vapors from plastic, paint, gasoline, other fluids, glues, sealants and upholstery are monitored in an enclosure specifically designed for this purpose.  Engine exhaust emissions and fuel economy are measured in a specifically designed laboratory for these tests.  

The EPA sets standards and carmakers design vehicles to meet them.  The fuel economy in real world daily use on the road typically is under the estimated fuel economy by about 10 percent listed on the vehicle’s window sticker.  This is a marked improvement over testing methods used a few years ago.  To learn more there is a wealth of information on the Environmental Protection Agency’s web site at http://www.epa.gov/fueleconomy.

I don’t know what engine is in your friend’s Escape but according to the EPA the average estimated fuel economy is about 25 or 26 miles per gallon depending upon the size of the engine.  It seems your friend’s vehicle is pretty close to their fuel economy estimates.

Leaky Sensor No Big Deal Yet

Question 3

My 1998 Altima SE with 30,000 miles is said to be in showroom condition.  Since 2000 the car is driven less than 1000 miles a year.  It was purchased new at the dealership where I take it every year for service.  Recently, the supervisor reported a leak from the speed sensor at the manual transmission.  He said that since the car is seldom driven it is not critical that I have this replaced.  It would cost over $200 to fix.

What is your opinion?  Would the check engine indicator show if it were a problem?  K.W.S., email

Answer 3

At this time it is not a critical issue.  If the sensor fails the check engine light should illuminate.  Additionally, more than likely the speedometer will go bonkers.  Also, since there is a leak of gear oil from the transmission drips may appear on surfaces where the vehicle is parked.  If this occurs have the issue repaired as a loss of lubricant in the transmission could cause excessive wear resulting in major work on the unit.

Leery Over Future Of RAV4

Question 4
My 2005 Toyota RAV4 stalled.  I had it towed to my local garage where a mechanic found the coil failed.  He also found a failed engine temperature sensor and had to replace the radiator cap because it was leaking.  He needed to add nearly a gallon of antifreeze, too.

My RAV has 110,000 miles.  Up until now I haven’t had a bit of trouble with it.  I purchased it new with the idea of keeping it for 10 or 15 years.  Now I am afraid a lot more is going fail in the near future.  I don’t want to be stranded somewhere.  What else will go wrong?  Should I keep it or get rid of it?  M.G., email

Answer 4

I’m sorry your car is giving you trouble.  You have been blessed with 110,000 trouble free miles.  This is unusual.  I’m also sorry about the performance of my automotive diagnostic crystal ball.  It says that it is impossible to determine exactly what will fail in the future.  It does say your car is getting older and parts will fail.  It also says along its journey parts will fail more often as it ages.  Through its mystic powers it clearly says that if the engine and transmission have received regularly scheduled and frequent preventive maintenance these major parts will perform for many years to come without major repair.  However, it says parts such as sensors, ignition coils and gaskets might fail due to age and mileage.  It also says that parts in the suspension and steering will need replacement and eventually wear will take over the engine and transmission.  It does not say whether you should get rid of the vehicle or if you should hang on to it.  It leaves this decision up to you.

Thanks for all of your great questions.  Dr. Gizmo can’t wait to answer more.

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 e-mail address drgizmo@hotmail.com  02/11/2013 ® DR. GIZMO © 1989-Present