Friday, June 6, 2014

Getting my hands dirty

Last November, my parents bought a new SUV, and rather than get next to nothing for their old one on the trade-in, they gave it to Michelle and me. 

That left us with three vehicles for two people, so we planned to sell our 2004 Ford Explorer.  The Explorer must have been listening, because a couple of days later, the Service Engine Soon light came on.  The friendly people at AutoZone checked the code for us, and the problem is something to do with the Exhaust Gas Recirculation Valve.

Before I get into the specifics of that repair, let me say, by the way, that the 2004 Ford Explorer XLT, with the 4.0L V6 engine, has been rated by several organizations that rate vehicles as one of the worst vehicles ever made.  The engineering of this particular vehicle is a model of incompetency--or, if your goal is to have the vehicle put into the shop for as much time as possible, for as much money as possible, then it was designed by a savant.

For example, the air conditioning system contains two separate features that (a) break easily and (b) require a minimum of 10 hours (if you are a professional, or two weeks if you are not) to replace.  One of those features is the door that opens or closes to let fresh air into the A/C system.  That door likes to break off and fall down, where it blocks the blower, rendering the entire system worthless.  You have to take the dash off to replace that door.

We jerry-rigged* a repair on that last summer, which took us about 4 hours total.  It's not a perfect repair, and we have full-time recirculation, but it works.

* - The term "jerry-rigged" is a Britishism, born during World War II, that referred to hastily repaired equipment that the Brits encountered as the Germans retreated.  ("Jerry" is a somewhat derisive term used by the British to refer to Germans.)  Some authorities believe that the term was a blend of "Jerry-built" (a similar term that referred to equipment that was poorly engineered to begin with) and "jury-rig," a sailing term that refers to the jury mast on a sailboat.  It is somewhat ironic that the Germans have developed a reputation today for solid engineering.

This latest problem, however, is an excellent example of good intentions gone bad.  Exhaust gas recirculation, which was first implemented in the 1960s, is supposed to aid in fuel economy and burn efficiency by circulating exhaust gases back through the combustion chamber.  The theory is that those gases contain unburned fuel, and recirculating the gases through the combustion gives the engine a second chance to burn that fuel.

On this vehicle, when the EGR valve goes bad, the entire powertrain system goes into "limp" mode.  That means that the engine loses significant power and the fuel economy gets cut by up to 50%.

In most vehicles, the EGR system includes an EGR valve and a sensor called a Differential Pressure Feedback EGR sensor, which monitors the content of the exhaust gases and adjusts the EGR for maximum efficiency.  When there is a problem with this system, sometimes it's the valve itself, but most of the time, it's the sensor that goes bad.  The reason for this is that valves are hardy components, while sensors contain sensitive electronics that go bad easily under tough conditions.  In most vehicles, the sensor costs about $30 and takes about 15 minutes to swap out, while the valve costs about $60 and takes about 30 minutes to swap out.

In the 2004 Ford Explorer XLT, however, some jackleg in the engineering department decided it would be a good idea to combine these parts into one part.  If one aspect of it fails, the whole thing has to be replaced.  This combined part costs $132 list (although you can get an OEM replacement for about $85).  The kicker, though, is that rather than putting it in an easily accessed location, it's hidden behind the throttle body (which has to be removed to access the EGR), and on top of that, the bolts that attach it to the intake manifold point toward the front of the engine compartment--in other words, you have to access them from behind the engine, near the firewall.

This turns a 15- or 30-minute repair into a 3-hour project (under the best of conditions).

Between the holidays, severe cold weather, my surgery, and my recent back troubles, we have not gotten around to fixing this problem--something we deemed necessary before we could sell the vehicle.  But this week, I decided to pick up the problem and try to get it solved.

After gathering the necessary tools, today I opened the hood and began disconnecting the throttle body.  Because it has never been removed, that was a challenge.  I did finally get it removed.  What I found inside was beyond disgusting--a solid 1/8-inch layer of carbon soot coating the engine side.  But I did get that cleaned up and set aside, and it looks brand new.

The next task was to remove the EGR valve.  I managed to get through the first two steps before a storm came.  I may get back to it this afternoon if the weather allows it.

When I tell people that I work on my own vehicles, they often ask me why.  After all, why not put that time to more profitable use by working on other projects, and leave the automotive work to the professionals?  I could do that, but there is just something about getting my hands dirty, about figuring out a problem and fixing it myself, that gives me a great deal of satisfaction. 

At least until I hit a snag.  I've got my fingers crossed.

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