Folks,

I did an advanced search here to see what others think on the topic, but most of what I read are related to specific issues or or outcomes of traditional troubleshooting activities. Over the last several weeks, I've been doing a fuel efficiency study to see how my 2.5L Ranger is performing now that she is into her 12th year. As far as I can tell, the truck is still giving me the same mpg that I observed when I bought the truck new, albeit that back then, my fuel observations were more arbitrary. I'm presently at 94.5K, so I'm closing in on 100K and perhaps the associated PM activities that need to be performed then. I've always assumed that I would change out the plugs and wires at that interval, but given the sustained performance, I'm wondering whether the PM activity is warranted. This being the case, I wanted to reach out to the FTE community to see what folks have done, other considerations you have, and recommendations on when an owner should intervene (and not necessarily wait for something to breakdown catastrophically, e.g. dead coilpack or toasted wires).

I'm an advocate of using things up, but not necessarily until its worn out completely or beyond its indicated performance and usefulness. Many here appear to be similar advocates given the many posts where members/guests here pragmatically approach problems without throwing money immediately at new/replacement parts without some relative certainty that something needed replacing. For example, while I see some browning around the boots on the plug wires (coilpack end), I don't appear to be experiencing any adverse consequences; not itching to replace as a result. Yet, if members here have experience and comprehensive understanding that I don't have (I'm a weekend mechanic in my own garage), I'm all ears to the input. Optimizing personal spending while not compromising safety and performance. Anyway, I'll open it to the group here to see what I can learn.

Thanks in advance!

Kevin

 

I would go ahead and do plugs and wires. When I changed the plugs I did notice the gap was definitely out of spec even though the truck was not suffering from it. Something else to think about is a fuel filter and replacing your rear diff fluid.

I'm like you though, I never noticed degrading performance from my truck. My gas mileage has in fact gone up since I bought it 7 years ago.

Do you have the stock filter? and do you change it or clean it?

 

Granny,

Good points to remember. I have many original parts in the truck now. I've change air filters over the years, but the fuel filter is still the original one. Same on the differential fluid, but I've done the reading on changing that out. Tranny fluid too. I could be on borrowed time with some of these items. I've refreshed the power steering fluid in an attempt to eliminate the power steering pump whine. Most of the other perishable parts are still original too (PCV, brakes, etc.).

I had an 85 Escort; gave me over 40 mpg on the highway. I changed the plugs and wires anxious to see if I'd do even better; got worse. This lends to some of my search for knowledge here. I've wondered why I had the loss, with OEM wires and properly gapped plugs. So, I'd hate to do the tune-up with the Ranger to experience a loss. Folks here have posted that the platinum plugs they took out at 100K for change showed very little wear. If the wires and plug configuration that's in there are working and no experienced loss in power or economy, then is the change warranted? I'm leaning toward the change given my earlier data is foggier, but I'm hoping for the responses here to give me data one way or the other.

Thanks for the input...and reminders!

Kevin

 

Have you pulled your plugs to check the gaps? That would be a good thing to check before buying new ones

 

Granny,

I haven't yet, but it was going to be my first step. I posted here in a separate thread a few weeks back regarding accessing the obstructed plugs, but of course I'll make it simple on myself and access the easiest ones.

Speaking separately at work, my fellow associates recommended that I wait until I see signs (e.g. loss of mpg, loss of power, etc.). Perhaps, but maybe not.

Kevin

 

The orig PP plugs on my 2000 were replaced by me at 100,000. The exhaust side plugs were more chewed up than the intake side. I installed autolite PP plugs becuase ford for what ever reason stopped making PP plugs for the 2.5. I also installed motorcraft plug wires. I plan on doing the same thing at the next 100,000 mile turnup. At 160,000 miles, i get the same gas mileage as I did when i bought the truck new in 2000.

 

biggest piece of crap on the plant earth, next to the pinto and gremlin
I had an 84 and 88 and all those years sucked ear wax...
Rubber timing belts breaking between 60,000 to 80,000 miles and leaving me stranded more than once. Water pumps that run off the timing belts that go bad and strip the timing belt fun fun fun
Ford's most retarded TFI ever used went on these fords. Suckers would over heat and shutdown the engine then leave me stranded again. Ford refused to fix their TFI module issues and left people stranded all over the place.
These are a few of the reasons I refuse to buy ford cars anymore. I buy ford trucks and Toyota cars.

 

Thanks gp. Sorry your Escorts were a source of frustration. I had the opposite experience with my 85 and 90 GT. Great mileage and reliability. My 90 quite on me once because of a bad module (literally fell apart), but my 1.6 was with a carb and the 1.9 fuel injected. That said, I currently have Honda cars and Toyota van. But I would consider another Ford car, the recent designs have appeal, but I haven't investigated their quality yet (I'm a Quality professional, so I tend to be skeptical until I have objective evidence that confirms claims).

I thought about which plugs would wear fastest; maybe the exhaust as you've observed. Were you experiencing any power/economy losses before the change? Did you notice a pick up for one or the other, or both, after you changed the plugs?

Kevin

 

I didn't notice any power loss before replacing the plugs. After replacing I may have got about 1 mile more per gallon. I did not notice any power gains after replacing plugs and wires. Instead of using PP plugs I may use thin wire Iridium plugs since that is what Ford recommends now.
I plan on keeping this truck forever and hopefully it will make it to 300,000

 

gp,

I'll look into the plug issue. Funny that Ford doesn't have the OE replacement anymore, but my 2000 is out of luck on many levels to that regard. It looks like I'll be moving more and more to aftermarket solutions as the Ford OE replacement parts become extinct! Not my desire, but the case nonetheless. Thanks for the additional data.

Kevin

 

One thing about replacing spark plugs and O2 sensors before they show signs of wear has to do with cost and ease or replacement, and the consequences of what happens when they fail. Allow me to explain.

Spark plugs and O2 sensors have something in common. They thread in, and the threads have to deal with a lot of stress. If they are allowed to remain in the system for longer than the recommended replacement interval, they can begin to seize into their ports. Then this happens, it makes removing and replacing them when they do eventually fail much more difficult, in the case of O2 sensors, sometimes even impossible. Both items should be replaced, or at least inspected before 100,000 miles. When they are installed, anti-seize should be used.

Problem number two is that with either item, as they wear they will have an effect on the way combustion takes place. Also as they wear, they can affect each other. If a spark plug gap starts to get larger, it may still fire, but the coil has to build more charge before it fires, essentially retarding the timing slightly. This may have little or no apparent effect, but the slightly later timing results in the formation of carbon deposits, which over time do have an effect. If these carbon deposits form on the O2 sensor, they can alter its readings, typically telling the computer that the mixture is leaner than it actually is. The computer responds by slightly increasing the injector pulse width. The results in increased fuel consumption, but also results in increased carbon deposit formation. There you see, the visious cycle has begun. The rich mixture can also start to foul the spark plugs, though that would be a fairly extreme case.

The third problem is all of these effect a system that is dependent on those working properly, and that is the emission system. Catalytic converters are expensive to replace, but will continue to work properly on the condition that the engine is kept properly tuned. Carbon deposits from rich reaction interfere with the reaction sites on the catalysts surface and make the converter less effective, and over time eventually become the dreaded P0420 or P0430 code which indicated the converter is no longer functioning correctly. The EGR system doesn't like carbon deposits. The P0400 series codes are often the result of the amount of carbon the engine has been producing.

This is why it is recommended to replace, or at least inspect those components before you start noticing problem with them. If your fuel economy is good, thats fine, but you want to keep it that way, once you wait till it starts to decrease, the cycle has already started, leaving your only real solution as replacing all the parts that affect each other. And if you wait till smog components start to fail, now you are talking about serious expense.

 

Khan,
Nice job creating potential scenarios of what could happen! In the Quality world (where I spend my days) this is a great example of Optimization vs. Maximization (gaining maximum life out of a part while compromising the System). Maximization can be, and often is, a dirty word.
All,
My take so far (and thank you to everyone who have contributed so far):

• Very important to keep manufacturer’s recommendations in mind when making decisions – although they may be guidelines, specifications are established by folks with greater expertise and knowledge than the average Joe
• Inspect before replacing; optimize your expense but do not maximize part life. Inspecting also has other hidden benefits as you point out (e.g. keeps parts from seizing mechanically, allows adjustment in some cases, etc.)
• Consider downstream/upstream effects when making a decision - System optimization is the aim; not seeing how long a component can go before failure (and may maximize overall expense in the longrun)
• Stay away from 84 Escorts w/TFI unless you suffer from earwax build-up (otherwise doctor greenpus endorses its use)

Thanks folks! Back to the group….
Kevin

 

Hello Granny,

Yep, you were right. I took the plugs out and replaced them. The gaps were much larger than spec by about .010-.020. The tips of the electrode still looked good but the side electrodes were worn away (eroded and malformed). The wires were difficult to get off and broke in a few instances. I saw some oxidation and carbonization on the terminals and some tiny white ***** of contamination. Haynes suggests that owners don't wait until the scheduled 100K (mine had 95,700) as they will show wear. That said, I wasn't seeing a loss in mileage or power. On a quick ride around the block, truck feels exactly like it was before the change. I'll take it to work tomorrow and see if I notice anything, but I'm not expecting too.

Kevin

 

An added dimension to spark plug replacement: I don't know if the original plugs were copper core. If they were and you upgrade to double platinum plugs, you may notce a slight gain in performance and fuel economy. That was my experience on my '91.

 

Hey there Michigan,

I went with the OEM replacements as it seems that most here at FTE seem to point that way. My experience as well when it comes to some of the gimmickie plugs (splitfires, etc.). Paid the price but never noticed any improvement and mainly found I had to replace them sooner. Wires too. So, staying stock for the moment.

You were probably right (other thread) regarding the installation process. I spent a good deal of time on #3 and #4 plug and wires (mainly the wires).

Kevin