When to Replace Spark Plugs and Wires

[Kowboy]

First a little history. I bought my truck about 5 years back and am the 2nd owner. Truck came w/ 116 K miles on the clock and now has about 157 K. The truck came w/ an extensive service history all written down in a oily / dirty garage book. Golden for the next owner / me. I saw where he religiously changed all the fluids: brake, motor, radiator, tranny and rear end. No part failures were recorded. Records were there for air filters and tires.
I did notice that the spark plugs were not recorded as replaced in this log book. I ignored this as he was so prompt at everything else. The little truck ran flawlessly and gave good gas mileage so the plugs must have been replaced by now. Today I go off and purchase a set of Motorcraft plugs and a Bosch wire set. A Motorcraft wire set was not available from my parts guy. Pulled the #1 plug and saw that the plug had a PG suffix / original plugs from the factory and gapping was .072, nearly gone. The #2 and #3 cylinders looked the same, clean firing but worn badly. Cylinders 4-6 were worn down to a gap of .107. I made a big mistake at assuming that the service had been done. Took it for a test run and I now have the power that I thought the truck should have. Lesson learned.

 

[97RangerXLT]

Well look at it this way, you now have another indicator that the records in that oil soaked book are accurate

AJ

 

[Kowboy]

Not the best way to find out though. I could of had a little action going on between the spark and the piston tops. OUCH!!!

 

[Bronco638]

I just changed the plugs on a new (to me) 2001 Edge with the 3.0 Vulcan. They were Bosch Platinum plugs with Bosch wires. All of the plug gaps were at least .070 but the plug tips were a nice tan-ish grey. So, the plugs had been changed at some point but no idea how long ago. The Ranger has about 126K on it now and I've put less than 500 miles on it. It does seem to have better power now. It's a time consuming job but not that hard. I don't know what the change interval is but I don't think I'd let it go for more than 50K miles (on the new Motorcraft plugs/wires).

 

[Kowboy]

I've got to say that this little 3.0 really loves the tune up recently done to it. I can now let out the clutch without putting my foot on the accelerator pedal. I can do this even when going up a small incline. I find more range in each gear and smoother acceleration. I now believe I could pull that boat and trailer that I've been wanting. This could get expensive.

 

[kimcrwbr1]

My rule of thumb is if you dont know how old they are change them that goes with all preventive maint parts, plugs, wires, PCV, filters, vacuum lines, belts, hoses. Especially with fuel prices now a days. Just pick away it dont take long to know where you stand.