I am an old guy (63) and you folks have helped me so much. I have a 1999 ranger XLT extended cab, 4 cyl "LIMA" according to all the responses I got. 5sp manual and it has been well maintained as I bought it new. Well, the paint is starting to flake off in several places but it is technically very sound. Front to back. But, I have a question, It has NEVER had new plugs or wires and has 123K miles on it. It has never gotten better than 20-22mpg on the highway, but it is now "losing power" UNDER ACCELERATION, and the mpg is going down rapidly, (15-17 mpg. From all I can tell it needs new plugs (they are factory as well as the wires, but from what I have read , they are good for 100K miles) Is that all I can do to "tune it up"? What should I replace other than the plugs and wires ? Should I do anything to the injectors, timing, and other things. I had a mechanic tell me the exhaust and intake manifolds must come off to just replace the plugs, not counting the wires. $450 plus to do the job. Does this sound right? I am on a fixed income and don't have a lot of extra money, so this is really a concern for me. Thank you in advance for any guidence, I can't afford a new truck and I need to keep this one running as long as possible, lol. Quite simply, what do I need to do to fix the problem as cost efficiently as possible. I have folks trying to sell me **** I know will not help. Your honesty and willingness to help is what I will depend on. Thanks again, SSSSSSSSSSS

 

No that does not sound right. It is just a pain in the @$$. Plugs are about $15 and wires are about $35 online. It probably needs a fuel filter and new EGR valve as well.

Here is a video of a guy changing out the plugs on a 99 Lima.

 

Man !
That is a PITA !
I would have removed the intake manifold.

Clean you MAF sensor too and of course change you air cleaner.
There is special cleaner for the MAF sensor, follow the instruction on the can, don't use Q-tips and touch the filaments on the sensor.
Any oxygen sensors should be replaced too.
Even though there is no CEL, they become less efficient when they get old and your fuel mileage goes down.

 

Thanks for all the response. I may be able to pull this off on my own, lol........ fuel filter is new, but I am not familiar with the other sensors mentioned (MAF sensor too, where and what does it do?) and of course change you air cleaner (air fuel, and cabin filters are new).. I have no readings showing a problem with any of them (oxygen sensors should be replaced too.
Even though there is no CEL, and EGR valve is new as well) . This truck has been maintained to factory specs for almost 20 yrs. If anyone has the part #'s for wires and plugs I would be grateful. I have been told I need to use ONLY "Bosch Platinum" plugs only, and I do not recall the brand of expensive wires I was told to buy. Tks....

 

I buy Motorcraft. I have had some issues with other brands of plugs.

 

Hey Steve (WALI)
MAF _ stand for "mass air flow" _ sensor
It's located right after the air cleaner element in the air tube _ some have 4 wires coming out, some have 5

It measures the flow of air into the engine given how much the throttle plate is opened.
It has 1 or 2 fine filaments that are heated.
The computer heats the filaments, so when air passes over them, the filaments cool off.

The more air that passes, the cooler the filaments.
This in turns lets the computer know how long to keep each injector open depending on how far the throttle plate is opened.

What happens over time is the MAF sensor gets dirty and relays false info into the computer.
Dirty filaments tell the computer that they are colder then they really are.
So the computer keeps the injectors open longer then they should be.

That's a maintenance thing, some clean the MAF every year, some 6 months or less.
It depends where the truck is being driven.
Being driven on a dirty dusty logging road would require that it be cleaned more often as apposed to highway driving.

About oxygen sensors, even though you may not get a CEL, the chemical in them that makes them work, gets used up.
They become less efficient _ the stay working well enough so you don't get a CEL, but ones fuel economy begins to suffer.

If you still have the original ones (don't know how many there are in a Lima engine), you should replace them.

Clean the MAF sensor first though, it's easy and inexpensive, see if things don't improve.

You said "the truck has been maintained for 20 years", have the oxygen sensors ever been replaced ?

EDIT:
You said you have a Lima, that would be a 2.5 liter ??? Only one listed over at Rock Auto for 1999.

When I check you personal info page, it says you have 4 liter (which is a V6) ????

We need to clear this up.

Can't give you any links for parts or part numbers until I/we find out what kind of engine you have.

EDIT:
Here's what you MAF sensor looks like for the 2.5 litre. (yours is a 4 wire, you will need a TORX head tamper proof bit to remove it)

http://www.rockauto.com/en/catalog/f...ow+sensor,5128

 

Here's a very informative post from Ron on how things work.
Read the whole thread.

https://www.ranger-forums.com/4-0l-o...3/#post2131104

 

Thanks Ron & Jeff ! You said "the truck has been maintained for 20 years", have the oxygen sensors ever been replaced ? ANSW~ NO shop said no indication of failure

EDIT:
You said you have a Lima, that would be a 2.5 liter ??? Sorry, I changed it. It is a 4 cyl 2.5 Lima from what I have been told.
CLEARED UP ! :-)



EDIT:
Here's what you MAF sensor looks like for the 2.5 litre. (yours is a 4 wire, you will need a TORX head tamper proof bit to remove it) TKS, I never knew it existed till now. I guess my mechanic didn't either, lol. It has 4 wires and the tamper-proof torx, the other side looks almost like a "blind rivet"? Should I buy the whole assembly or just the "black box"? More Information for WALKER PRODUCTS 2451039

 

Don't buy anything, just clean it.
Sensors don't really fail.

Get the proper MAF cleaner that comes in a can and follow its instruction.
It will say MAF cleaner on it, or something to that effect.

You may get a new sensor of you want, but try cleaning the original one first _ you will probably save some money.
If you do get a new one, just the black box, but the housing that the black box is screwed too will have to be cleaned.
Use the MAF cleaner for that too.

Wouldn't hurt to replace the oxygen sensors either, they've been in there for 20 years.
They're not that expensive, but they can be a bear to get out sometimes.

You only have two of them on yours _ upstream and down stream.
They are located on the upper exhaust nearest the manifold and usually just before the catalytic converter _ that's the tough one to get out.

I had to use oxy/acetylene tourch to get mine loose.
Maybe yours will come out a little easier.

 

WOW tks Jeff R 1....... great help and info. I wish you lived here in SW FL. LOL...... SSSSSSSS ps, the whole (MAF) assembly is cheaper than the sensor by itself by 20 + bucks, lol........

 

Ok all you great folks I am going to replace the plugs,wires and sensors I have been told replace. Would anyone be kind enough to list what i need to use to get it all correct? I am going to replace ALL the wires, plugs, O2 sensors, and the "Map" on the intake (or clean it properly) What I am looking for is all the correct stuff on a LIMA 4 cyl that has121K miles on it and has NEVER been changed. It has run perfectly and always gotten about 20 mpg +- but recently it has dropped power and is getting 15 +- MPG . If any of you genius know to tell me what to do, and what to use it would be greatly appreciated. I am an old bastard (64) and some of this is hard to do, but I still feel I can do it. I just need a LIST (PLEASE LIST ALL THE THINGS I NEED and the brand and parts # would be great as i am tired of being screwed", lol....) of what to buy and what will work best for my "99 Ranger. Thanks So much in advance....... SSSSSSSSSSSSSS

 

At that sort of mileage, while you have it apart, pull the egr off and clean the passage from the egr into the throttle body or you will eventually end up with a 401 code for insufficient egr flow.
When I pulled the plugs on my '99 model 2.5, it had 165,000 miles on it and ran pretty poorly. The electrodes were unbelievably worn out. I opted to use NGK iridium plugs. They were expensive, at around $9.00 each, but those will most likely be the last plugs unless I pull and rebuild the motor. I has 207,000 miles now and runs good. It still doesn't use a whole quart of oil between changes. Mine recently threw a "slow response time on front oxygen sensor" code. I replaced both sensors. That was a PITA from the sensors being rusted in place. Luckily I have all the tools. An angle grinder with cutoff wheel, torch, 6 point socket and impact wrench got the sensors out. Now it runs good again.

Fuel mileage isn't really great, and never has been. Around town, it is around 18. On the highway it will sometimes get 21. For parts, if It isn't urgent, I get my stuff from Rock Auto. Saves a TON over local supply houses. Love my Ranger, it is the best vehicle I have ever owned and I am 64 years old. Going to give it a new epoxy paint job and bed coat this year.

 

As fast says, Rock Auto is a good place, here are some links.
Oxygen Sensors for sure. (up stream and down stream, don't mix brands up, although it probably doesn't matter, don't but the "Economy ones")
Spark plugs
Wires
DPFE sensor (if you are still running the metal one, the lines coming from it need replacing too, check links for both)

Clean the MAF sensor after replacing the above. (if everything is fine, then leave the MAF sensor)
You can leave the coil pack for now and replace it if things don't improve.

1999 FORD RANGER 2.5L L4 Oxygen (O2) Sensor | RockAuto

1999 FORD RANGER 2.5L L4 EGR Pressure Feedback (DPFE) Sensor | RockAuto

1999 FORD RANGER 2.5L L4 EGR Pressure Feedback (DPFE) Hose / Pipe | RockAuto

1999 FORD RANGER 2.5L L4 Spark Plug | RockAuto

1999 FORD RANGER 2.5L L4 Spark Plug Wire Set | RockAuto

Here's some reading about oxygen sensors, so choose the "heated" type at Rock Auto.

http://www.autorepairinstructions.co...xygen-sensors/

About the DPFE/EGR system. The original ones were made from metal and what happened is that the corrosive exhaust gasses (and water in the exhaust) corroded the metal ones internally.
Once the corrosion reached the small circuit board inside the sensor, the board didn't last long.
This condition may not produce a check engine light, but will cause problems eventually, poor starting, stalling and or slight jerking going down the road at low speeds etc...

http://www.searchautoparts.com/motor...-ford-does-egr

The down stream oxygen sensor probably won't come out easy, it's been in there for 19 years.
I had to use an Oxygen/Acetylene tourch to get mine out. The exhaust pipe surrounding the sensor had to be heated to cherry red/orange before I could break it free.
You may want to take the truck to a muffler shop and have him do that.
Although, the shop will probably want to replace the sensor for you.

 

Well, I got all the parts with the exception of the "EGR", not sure where it goes, lol.......I may have to take it to mechanic to get the O2 sensors replaced, (old fat men don't get down on the ground very well, not to mention getting up, lol) but I feel like I can do the wires /plugs ect. And good lord, what is a (DPFE sensor (if you are still running the metal one, the lines coming from it need replacing too, check links for both) where is it at, and what does IT DO? I used to be a great mechanic up until the early 80's, when all the "lectrics" started showing up on everything. My wife has a 2015 Mazda 5 and I do not recognize a damn thing under the hood, lol....
Thanks for all the information !