Past Northwest Herald Dr. Gizmo Column June 15, 2012

06/15/2012

"Dr. Gizmo"
By Phil Arendt
 
Sensor Fault, Maybe Not

Question 1
The check engine light turned on in my 2002 Volkswagen Jetta.  It has a 5-speed manual transmission, 2.0-liter engine and 87,000 miles.  The engine ran fine despite the light but when the car did not pass an emissions test I took it to an auto parts store for testing.  The man at the store tested a computer and found a code that indicated a problem in the mass air sensor.  He said I should take the car to a repair shop to have it checked out.

Right now my finances are tight.  I need to have this fixed so the car passes the emission test.  Do you think replacing the air sensor will cure the problem?  C.N.A., email

Answer 1
It might.  There are about three different malfunction codes for your car that indicate trouble in the mass air flow sensor.  All three codes could mean that the sensor has an internal fault that requires replacement.  Be this as is it may, there may be a problem in the sensor circuit such as a faulty ground connection or even a fault in the power supply that causes the trouble.

Additionally, it is also possible there are issues in the engine intake system such as vacuum leaks, faulty intake flap or problems with other sensors that can cause trouble codes to appear.  While this is rare, even the engine control module might have an internal fault that triggers the check engine light and codes indicating a problem in the mass air flow sensor.

Before the sensor is replaced the intake system should be checked for leaks.  An examination of the intake ducts including the air filter housing may find a loose clamp or there could be a crack or hole in a duct.  Maybe the entire problem is caused by grime in the mass air flow sensor that cleaning may correct.  Just maybe a vacuum line is cracked or loose on a fitting.   Any of these conditions could cause codes indicating a fault in the sensor. 

Before replacing it, consider asking an experienced technician to take these suggestions into account for it may not be necessary to replace it.

E85 Fuel Causes Rough Idle

Question 2
I have a 2007 Dodge Ram 1500 that idles rough.  It has a 4.7-liter flex-fuel engine.  To save money I use E85 gasoline.  When the engine is running on E85 it runs rough especially in the morning when it is cold.  After a tank or two of regular E10 gasoline the engine runs smooth at all times. 

I took my truck to my local repair shop.  A technician ran several tests, but there were no codes in the computer.  He replaced the spark plugs, cleaned the fuel injectors, tested the fuel pressure and engine compression.  The engine checks out fine, but on E85 gas it still runs rough.

I want to use E85 gasoline to reduce fuel costs but since the engine runs rough I am forced to buy more expensive gasoline with 10 percent ethanol.  Do you have any suggestions that will cure the rough idle?  T.T., email

Answer 2
There are a couple of issues.  Burning E85 gasoline may not reduce fuel costs.  E85 does not produce as much energy as E10 gasoline and E10 gasoline does not produce as much energy as gasoline that is not mixed with alcohol.  Unfortunately you cannot purchase pure gasoline in this part of the country.  As a result of differences in energy produced, gasoline mixed with 10 percent alcohol produces more over gasoline that is 85 percent alcohol.  It is very likely your truck’s fuel economy will increase if you burn E10 gas.  In doing so you could save money with an increase in miles driven per gallon and cure the rough idle condition.

Compare the fuel economy between the two fuels to decide which fuel to burn.  If you are not sure how to perform a fuel economy test there is a great deal of information at the Environmental Protection Agency government web site http://www.fueleconomy.gov or do a rough calculation by dividing the number of miles traveled by the gallons of fuel consumed.  For example: 200 miles traveled divided by 10 gallons consumed equals 20 miles traveled per gallon or mpg.  

If you decide to continue to burn E85 fuel, engineers at Dodge have learned from dealership repair shops and motorist feedback of the rough idle concern.  They developed a repair that involves updating the software in the engine control module.  To have the work performed a technician with an up-to-date factory StarScan tool can do the repair according to technical service bulletin number 18-039-08.  Since this is not a free repair. Ask your favorite technician for an estimate before authorizing the work. 

Wiring Diagram Not Available 
Question 3
Recently, I purchased a 2005 Smart ForTwo with a 3-cylinder engine.  It has 89,000 miles on the odometer.  I use it as a second car to drive to work about four miles from home.  The other day the car would not start.  The engine cranked and cranked but would not start.  It didn’t act as though it was getting any gas even though the tank was nearly full.

I had the car towed to a local independent repair shop where a mechanic determined that the fuel pump is not working.  He found that the pump is not getting electrical power even though the fuses are good.  The problem is that he does not have a wiring diagram.  He needs this to do a proper repair.  He said the resources available to him do not have a wiring diagram for this car.  He said he could make a temporary circuit to power the pump, but this is not a permanent and proper repair.  He suggests that I take the car to a dealership to have the problem repaired.

I had him install a temporary circuit so I can drive the car.  Can you tell me where I can get a wiring diagram for my technician?  Do I have to take the car to a dealer to have a proper repair?  F.D., email

Answer 3

A check of three repair manual resources did not find wiring schematics.  Also, the internet did not provide any useful wiring schematics from an anonymous donor.  While this may seem strange, sometimes auto manufactures do not release repair information to the automotive aftermarket.  This causes issues such as you have encountered.

To have the car repaired to the factory original configuration, consider taking the car to your favorite Smart franchise dealership where all the resources are available to repair your car including a factory trained technician.

Water Combined With Electricity Causes Major Problems

Question 4
Recently, my 2008 GMC Arcadia developed weird problems that cause concern.  My vehicle has 67,000 miles, a 3.6-liter engine, and automatic transmission.  One problem is that the air bag light turned on and now the engine cranks as if it wants to start after I turn off the ignition and remove the key.

I took the vehicle to a reliable repair shop.  The mechanic wanted to check the computer for trouble codes even though the check engine light was not on.  He said his computer diagnostic tool does not communicate with any of the several computer modules in the vehicle.  He thought that maybe the problem was with his tool so he borrowed one from another shop.  The same thing happened with the borrowed tool.

Now he thinks there is a problem in one of the computer modules but he said computer modules do not fail too often so he is not sure this is the trouble.  He suggests that I drive the vehicle until l have time to leave it for a few days so he can determine the cause of the problems.  Do you know what’s wrong?  L.W., email

Answer 4
Your car is possessed.  You better seek divine intervention.  All kidding aside, the problems may indeed be caused by a lack of communication between control modules. 

Your technician is correct.  Modules do fail, but not too often.  Often when a module fails due to faulty wiring or a fault within a module communications are severed to diagnostic equipment such as diagnostic scan tools. Technicians must use this tool plus other equipment such as lab scopes, also known in the good old days as oscilloscopes, to determine diagnostic trouble codes, perform circuit tests, test modules and accessories in circuits such as power windows, air bags and ignition circuits to the starter motor plus every electrical device in a vehicle.   

As for the trouble in your vehicle, the cause might be due to water leaking into the passenger compartment.  Check the carpeting to see if it is wet.  If so, perhaps there are water leaks from the sunroof.  I know you might say I’m crazy because you have never left the sunroof open in a rain storm but believe it or not sunroofs are designed to leak.

A sunroof assembly has drains positioned strategically at the corners that run down body pillars to drain water.  Water is channeled to the drains.  It then drains through tubes and body and out the bottom of the vehicle.  When the water does not drain, it soaks the interior.

As you know water mixed with electricity can cause all kinds of trouble including electrical shock and death.  While death from electrical shock from a non-hybrid vehicle is highly remote you still do not want water wreaking havoc on electrical devices. 

A check of the front carpeting is in order.  It may be a good idea to pull the carpet up to see if moisture is under the carpeting.  Many Arcadias, Buick Enclaves and Saturn Outlooks have developed water leaks due to problems in the drains and in some cases body seams.  The water drips on wiring and modules and causes symptoms such as you describe.

While demons are not causing unexplained symptoms, H2O may be the culprit.  Ask your technician to check technical service bulletins numbered 07-08-57-002E and 08-08-57-003A.  Also, since these problems may be due to faulty manufacturing or design, consider asking a dealer shop to check out the problems.  Sometimes the factory gives special dispensation in the form of free repairs in vehicles with these conditions, but there is no guarantee your car will be repaired for free.

Blown Radiator Hose Causes Spark Plug Misfire
Question 5
Recently, a hose at the top of the radiator blew and leaked antifreeze all over the engine compartment.  I was able to replace it.  Also, I washed the entire engine compartment with a pressure washer of all antifreeze.  What a mess.  I never thought antifreeze was so slimy. 

The trouble now is that the engine runs fine at slower speeds, then it misfires at moderate speeds and then at higher speeds it runs fine again.  This did not happen until after the hose blew.  The engine did not overheat.  The cooling system does not have any other leaks that I can see and the coolant jar remains full. 

I checked all of the electrical plugs and connections in the engine compartment to see if they are wet with antifreeze.  I cleaned all of them inside and out with brake cleaner and electrical contact cleaner to make sure they are dry.  Some connections had grease in them so I purchased electrical grease from an auto supply store to treat the plugs.   Also, I removed ground connections on the engine and body to make sure they are clean and dry.

My car is a 2002 Ford Focus with a 2.0-liter duel overhead cam engine, automatic transmission and 122,000 miles.  I purchased it when it was new.  It’s in great condition.  Last fall the engine was tuned with new wires and plugs.  Up until now it has never given me any problems.  Do you have any suggestions?  R.B., email

Answer 5

Sure.  It’s time to purchase a new car.  I’m just kidding.  Since the engine did not overheat and the fact that the coolant level is not dropping, there likely are no internal leaks such as those associated with a failed cylinder headgasket.  A sigh of relief is in order, but if one hose sprung a leak it is a good idea as a preventive measure to replace all coolant hoses.

What you describe as a misfire should illuminate the check engine light but sometimes strange things happen that defy analytical diagnostic thought.  I learned a long time ago that anything is possible so it is possible the engine misfires while the engine control module is not illuminating the check engine light. 

Since your description leads me to believe the engine was soaked with antifreeze, and water from a pressure washer, it was deluged with both liquids.  Also, since you apparently have the busted knuckle do-it-yourselfer spirit, remove the spark plug wires from the spark plugs and examine the spark plug wells.  I suspect the spark plugs are drowning in water and antifreeze.  If so, blow compressed air in the wells, spark plugs and wires to make them dry as a desert and the engine likely will return to normal operation.

Instrument Cluster Displays A Different Language

Question 6
The instrument cluster in my 2005 Chevrolet Suburban quit working.  A friend suggested that I purchase a used cluster from a salvage yard.  He changed out the cluster and found that some of the lights were dim so he removed it and I returned to the salvage yard to exchange the part.  The man at the salvage yard agreed that there is a problem with the part and gave me another.  He also said to have the newest panel programmed at a dealer. 

My friend had a friend with a dealer scan tool who programmed the unit.  The trouble now is it displays an unfamiliar language.  My friend says I should return it.  The man at the salvage yard says nothing is wrong with it.  He says I should program it for the proper language.  I spoke with my friend’s friend.  He says the programming he did was proper.  Now I don’t know what to do.  Can you help?  H.B.R., email

Answer 6
I know a guy, who knows a guy, who knows another guy who has the answer to your dilemma.  And, if he doesn’t know, you are in a world of trouble.  All kidding aside, you can program the language.  It does not require specialized equipment except one digit from either hand.

The procedure is in your owner’s guide.  If you do not have a guide, purchase a brand spanking new one from your local dealership parts department or perhaps a used manual from your local salvage yard.  Also, an internet search might find someone has uploaded the entire manual.  You might be able to read and print the pages you need from a random internet donor at no cost except for office supplies and internet service charges.

To my knowledge the cluster communication options are English, French or Spanish.  If the option is any other language including Martian, changing the cluster display to your favorite language is rather simple using the “select” button protruding the face of the cluster. 

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@drgizmo.ws.  6/15/2012 ® DR. GIZMO © 1989-2012