Dr. Gizmo column dated August 24, 2012

 "Dr. Gizmo"

By Phil Arendt
 

Parts Replacement Not The Cure

Question 1
My 2006 Volkswagen GTI lacks power and the check engine light is on.  The car has a 2.0-liter engine.  I had the same problem a few years back when the car was covered by the factory warranty.  The warranty has since expired. 

I took the car to an auto supply store to have the engine tested.  The man at the store found three codes all related to the fuel pressure regulator and some codes for misfiring spark plugs.  He did not want to sell me a bunch of parts because he did not know what caused all of the codes.  He suggested that I take the car to a repair shop.

The car acts the same way it did when it was repaired a few years ago.  I found the receipt from the previous repair so I can purchase the same part.  The codes the man at the auto parts store found are, P2294, P2293, P0087, PO300, PO303 and PO304.

If I replace the part that previously failed, do you think it will repair the car?  M.R., email

Answer 1
Take the advice of the auto supply store employee.  Some of the codes are related to fuel system issues.  Other codes are for engine misfire issues that could be caused by a troubled fuel system.  The fuel system is highly pressurized.  If you do not follow suggested safety procedures you could be injured, cause a fire or worse.

Now that I have warned you, the trouble might be due to a failed fuel pump.  There are two pumps in your vehicle.  One is a delivery pump which is in the fuel tank and the other is a high pressure pump on the engine.  Additionally, there is a fuel pressure regulator and sensor.  Faults in any one of these parts could cause the trouble you are encountering.

You could purchase the part listed on your receipt and install it, but this may not cure the trouble.  Since it is highly probable your purchase is an electrical part you will not be able to return it for a refund or exchange as the general policy at auto supply stores or dealership parts departments is no refund or exchange of electrical parts.
Consider leaving this task to a pro.

Dealership Not An Option 

Question 2
My 2002 Honda Civic failed to start.  When I turned the key the engine cranked but would not start.  The car was towed to a repair shop where a mechanic determined that the green light for the security system is not illuminating.  He asked me to bring all the keys to his shop.  I brought all of them, but none started the car.

Next he contacted a locksmith.  The locksmith checked over the car, but could not determine the trouble. 

Next, the mechanic replaced the powertrain module but that didn’t fix the trouble.  Then he replaced a module for the security system.  Now the green light works but the car still does not start.  My mechanic reinstalled the old powertrain module and still the engine does not start. 

Now my mechanic wants to tow the car to a dealer to have them check over the car.  I don’t want my car taken to a dealer.  They charge too much.  Do you have any suggestions?  D.T., email

Answer 2

It appears that your technician has pinpointed the trouble.  The module for the Immobilizer theft deterrent system failed.  Additionally, it appears that the powertrain control module needs reprogramming.  It appears that your technician does not have the tool to reprogram it.  Since this might be the case, he wants to have a local dealership do the reprogramming work. 

Certainly you can tell him not to take the car to a dealership for this procedure.  Ask him if he has a relationship with another independent repair shop that has the equipment to do the work.  If so, the other shop can reprogram the module.  If not perhaps, you can find a shop to do the work or have the car taken to a dealership.

A/C Quits When Going Up Hills

Question 3
On a recent trip in my 2003 Ford Focus the air conditioner would cut out when going up a hill.  Once I returned home I discovered that occasionally the a/c cuts out during normal driving.  It might shut off for ten minutes and then start up again.  When the a/c quits, the fan works fine and the vents respond to my preferences on the controls but cold air doesn’t blow from the vents.  I checked the electrical connection on the compressor and cleaned it but this has not made any difference.

I took the car to a repair shop but tests found everything was working normally at the shop.  The shop manager says I should wait until the trouble becomes worse or bring it in when it’s not working.

What do you suggest?  K.P., email

 

Answer 3

Some system designs allow for the air conditioner compressor to shut off when the engine is under heavy loads such as driving up a hill.  This may be normal but since it quits during normal driving there likely is a problem.

There is a lot more to the air conditioning system than meets the eye.  There are relays, a high pressure switch, a low pressure switch, an engine control module, controls in the dash, the throttle position switch, temperature sensors and more.  Since the system worked normally during tests it is next to impossible for a technician to determine the cause of the trouble.  Be this as it may the trouble might be due to a poor electrical connection.

Suspicion points to a poor connection at the high pressure switch.  For some reason when designing the car the switch was placed in front of the right front tire where it can be exposed to water and dirt.  If you are so inclined check the plug and terminals.  If you are not an avid do-it-yourselfer, ask a technician to do the work.  Cleaning the connections and protecting them with dielectric grease may cure this condition at least until the next time they become dirty.

Transmission Has Seen Better Days
Question 4
I have a 2000 Chevrolet Suburban with a 5.7-liter engine and 139,000 miles.  I decided to have the transmission fluid changed.  A shop drained the fluid, replaced the filter and cleaned the pan.  The mechanic said he found a lot of black material in the pan.  Since the service, the transmission shifts fine when I first start out in the morning but after driving a few miles when the transmission shifts from second to third gear it does not shift smoothly into third gear.  There is a pause before it fully grabs and engages. 

I spoke with the manager at the shop that serviced the transmission.  His shop does not repair transmissions but after a short test drive he thinks the transmission needs an overhaul or replacement.  He suggested that I take the vehicle to another shop for repair.

Do you think the transmission needs an overhaul or is there something else causing the trouble?  F.T., email

Answer 4

There are vehicles that travel well over 200,000 miles without transmission trouble and then there are some that need a transmission two or three times during their service life. 

Tests should discover the cause of the trouble.  Since a technician found excessive debris in the pan it is more likely than not the transmission has come to the end of its service life.  An overhaul or replacement is the next step.

Weigh your options carefully when selecting a course of repair.  An overhaul may only be covered by a one year warranty.  A replacement transmission warranty may be much longer.  Also, consider price and what your future plans are for the vehicle.

Time To Visit Another Shop
Question 5
I drove home from work and parked my 2006 Volkswagen Jetta with a diesel engine.  The next morning I started the engine, backed down my driveway and the engine stalled.  I attempted to start it but it just cranked but would not start. 

I had the car towed to a shop that has been servicing it for the last few years.  Once it arrived at the shop a technician jumped it and started the car.  He was able to drive it into the shop but it stalled as he was pulling into his work area.  He did some tests but his equipment will not communicate with the engine computer.  The shop manager says it is likely the engine computer has failed but he does not want to install one because he is not sure this is the trouble.  He suggested that I have the car towed to a dealership.  He says that the equipment at his shop can’t program a new module.

Have you ever heard of anything like this before?  D.A., email

Answer 5

Without a doubt I have run into troubles such as yours.

It’s not common for an engine control module to need replacement but it does happen.  Additionally, not all repair shops have the specialized equipment to program this module.  Most independent shops use generic equipment that can do a great deal of testing on many different year, make, and model vehicles but there are limitations with generic equipment.  When it comes to programming engine computers many times manufacturer specific equipment is needed.  Most independent shops purchase equipment for specific brands that commonly visit their shop due to technician expertise and specialization in a certain brand of vehicles.  Some shops may specialize in Dodge repairs and the one next door may specialize in Toyotas. 

Since your present shop suggests towing the vehicle to a dealership there is no doubt a dealer shop will have the tools to cure the trouble but there may be a nearby independent shop that specializes in VW repair.  If so, you might consider towing the vehicle there for it is likely that shop invested in the tools to communicate and program the engine control module.

Two Heads Are Better Than One

Question 6

My 1998 Mazda 626 runs fine when driving but when I stop for a light or in traffic the 2.0-liter engine runs rough and stalls.  I have owned this car since it was new.  It’s in great condition.  I have followed the suggested service schedule in the owner’s manual.  It has 103,000 miles.

I took it to a local repair shop that has been servicing the car for many years.  The mechanic did not find any trouble codes in the computer, but during a test drive the engine stalled.  They tuned the engine and replaced an airflow sensor.  When this did not cure the trouble they used smoke to look for leaks and did some tests on the EGR and throttle sensor but could not find the cause of the trouble.  He checked the engine module and wiring but says everything tests fine.

Now the mechanic is at a loss.  The shop owner wants to take the car to a dealer for tests.  I trust their judgment, but I would rather not have them take the car to a dealer.  What do you think is wrong?  L.S., email

Answer 6

It’s not time for the technician to give up.  Perhaps the shop owner has another technician who can brainstorm with the assigned servicing technician.  Usually technicians working together can determine faults. 

Since there are no trouble codes in the engine computer it is time to go over all test results and perhaps redo some tests.

Since stalling can be caused by faults in the exhaust gas recirculation valve or leaks at the intake manifold the technicians might consider retesting these parts.  Since smoke tests were performed for leaks at the intake manifold they may consider smoke again or other methods to retest for manifold leaks. 

If the shop owner is adamant about taking the car to a dealership shop he must have a good reason for this decision.  Consider trusting his judgment for he knows the limitations of his equipment and level of technician expertise.  If he believes repairs exceed limitations and has a good relationship with a dealership this option is another path to a quick and lasting repair.   

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.  08/24/2012 ® DR. GIZMO © 1989-2012