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Hello, my friend took her 2002 Ford Ranger to Sears about two months ago to have the spark plugs and wires changed.  Long story short--they crossed up the five and six wires and two of the plugs recently broke and the others burned out.  Now the engine has low compression.  Does this sound like damaged valves, head gasket, etc?  I'm going to attempt to fix this for her. Thank's

PS, The engine is a V6 3.0  

first...

this is the coil for the 2002 ....



this is actually 3 separate coils all mounted to one base plate and wired together..

its a waste spark system.    the spark goes out one wire.. through a spark plug .. through the head block and other head.. across the other spark plug then up the wire back to the matching coil terminal to make a complete circuit...

i will have to look up how the spark plug wires are supposed to be.

i would like you to remove the coil .. turn it over and look to see if the bottom is cracked... why.. when they crack.. they leak high voltage out or in..


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next is a compression test...   compression testers cost just over 25 bucks... sometimes less.. but some stores have loan a tool sets behind the counter..  so cash out eventually is 0. if you bring it back.. these are back in the shelving. not in display packs..

list the compression on the individual cylinders..

pistons can be damaged..   carbon  build up can hold the valves open..  
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with a fresh set of spark plugs after the compression test..  and the wires hooked up properly..  how does it run???

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how old is the fuel filter???? could it be clogged???   that would decrease the fuel pressure and volume at the injectors causing the engine to run lean... while the computer tries to compensate for the low fuel pressure...



but . this is a returnless fuel system.. there is a pressure sensor on the fuel rail.. and a variable speed fuel pump... the fuel pump is controlled by a module somewhere in the truck...  

oh yea....  plug in an OBD2 scan tool or code reader.. some stores will come out and read them for you...

write them down..  not the description but the actual P0000 numbers.,..  

Sorry I left some info out in the first post.  She took the truck to Midas a couple of days ago when it started running rough.  They found the crossed wires, and did a compression test on all six cylinders.  I believe she told me the engine had 90pds in one cylinder 20pds in three cylinders and 0 pds in the last two.  They put new plugs in and said there was no guarantee how long that they would last since there was internal damage to the motor.  With the new plugs in the truck it still idles rough, but once it takes off it runs better.

PS. The truck has 90,000 miles on it. Her parents bought it new and it has been taken good care of.

Thank's for the reply..  

with that low a compression on several cylinders.. the truck would hardly run..

do another compression test...   your self...  or have a professional mechanic do it...

when you find a low cylinder...  you can squirt a single squirt of engine oil from a squirt type oil dispenser into the cylinder.. if the compression comes back up ... then the rings are probably bad...  stuck to the ring grooves by carbon ...


another question.. did the truck overheat prior to the current crop of problems..


get a second opinion.. in person..

there are if you have shop air available..   cylinder leak down testers.. that blow an adjustable calibrated amount of compressed air into the cylinder after presetting each piston with a remote starter switch..  

you could also have a clogged exhaust system ..  

No, the truck did not overheat.  I was wrong about the cylinder pressure.  The truck has 90pds in two cylinders, 40pds in one, 20pds in two, and 0pds in one.  My friend as a last resort called the District manager of Sears the other day, and he has been helpful---unlike the store manager.  She is getting set up with a third party mechanic and if he sais the internal damage was caused by the plug wires being crossed up then Sears is going to fix it for free.  I'll report back.  Thank's again for the info, good stuff to know.