2000 Explorer XLT 4.0 V6 SOHC Tune-Up Ideas

[puzzaa]

Hey guys I'm kinda new here so I'm trying to get some advice.

I've been the owner of this explorer since day one and its taken some crap. As of right now, it runs okay. it gets me from point A-B. the reason im making this thread is because right now its getting about 10 MPG, more if its a good day. it has close to 230,000 miles on it so i understand things are getting old and ive decided to give it a tune up. At 200000 miles i replaced the ignition system (spark plugs, wires, the pack the wires plug into), fuel filter, air filter, ball joints, u joints, and flushed out the coolant with new coolant. i just did a oil change at 225k miles. now im here on rockauto.com searching the parts catalog for things i should replace. as of right now im getting shocks (they are still the originals yikes), intake gaskets (upper+lower), and maybe thermostat (car doesnt over heat, it stays between cold and midway so im deciding to replace unless you guys advice against it).

fuel. im not sure if maybe its something to do with the fuel system? i replaced the fuel filter but i can do it again, they arent that expensive. but maybe clogged injectors, failing fuel pump, ...? im also noticing the engine will not turn over when its warm. it cranks but will not turn on unless i turn the car completely off and back on. then it starts almost immediately! i thought maybe it was a dirty IAC valve so i took it apart and cleaned it up as well as the throttle body. it seemed to fix it so it doesnt happen every time but it does still happen.

Sensors. based of the internet all of the sensors have something to do with fuel economy. should i replace them all? they will get expensive and im not sure if i need all of them. ive replaced the MAF sensor a while ago but i think it was a cheap one so it could be going bad. i get a occasional check engine light (before it was the MAF sensor so i replaced it ) but it goes away before i have a chance to take it to get the code read. any thoughts on this would be helpful.

vacuum leaks. i thought i heard hear a exhaust leak whenever i gave it throttle but when i went underneath i couldnt see anything obvious. but i did notice in the engine bay when i gave it throttle it sounds like the car is sucking up some air when its climbing RPMs (around 2-3k rpms) . im not sure if its supposed to do that or there is a vacuum leak. it was near the IAC on the top of the engine but there are so many places it could be leaking.

thanks for your help. any ideas on what items/fluids i should replace to help my engine would be great. just a little sidenote i havent replaced any of the fluids in my car besides oil and coolant. should i replace diff oil, brake fluid, power steering, etc. (i know im a bad person) im not completly sure but i think the guys at the transmission shop replaced my trans oil when they were fixing the problem with the O/D but ill check when i get home. thanks!

 

[XLTrunner]

First off, I'd scan the engine for codes. Just because the CEL light comes and goes doesn't necessarily mean there aren't trouble codes stored on the computer. Might save you a bunch of cash over replacing sensors needlessly. Secondly, by all means replace the fluids in the front diff, transfer case, rear diff, brakes and power steering. Never hurts to change fluids.

You mention poor gas mileage. 10 mpg is pretty low for a SOHC engine. My '98 gets around 21 on open hwy driving. And, probably in the neighborhood of 16 in combined city/hwy driving. Specifically, how is the truck running? The only clue you gave is that it's sometimes hard to start when with warm engine. If you can give some details, perhaps we can help suggest some things to check. I will say that, with 230K miles, the fuel pump could be giving you some warning that it's on it's last legs. But, that usually will show up with hard starts (cold or warm engine) and stumbling upon acceleration.

Why do you suspect vacuum leaks? Upper and lower intake gaskets are notorious for leaking...but, doubtful you'd hear them leak. They usually show themselves on cold startups...causing a rough idle. Then, as the engine warms and the gaskets expand, the idle smooths out. Also, vacuum decreases as you hit the throttle...so, the sound of rushing air you're hearing around the IAC when you manually open the throttle is probably just the normal in-rush through the throttle body.

 

[Jake100146]

Hi everyone,

Wasn't sure where to post this though I installed a led light bar 6 months ago using a relay hooked up to high beam and seperate switch near the steering wheel to turn on or off when I have hibeam on as well.

Though I washed my car today and came back to the garage to notice that the light bar was half on half off (flickering) and the car wasn't even on let alone the high beam.

It generally was only 4-6 diodes in the light bar that were on and flickering though the light bar still works when I properly turn it on.

It just has 6 diodes that flicker and try's to turn on the whole light bar when my car is just sitting in the garage without the ignition on or high beam..?

Does anyone think a little bit of water went somewhere it shouldn't have?

Thanks everyone

Jake

 

[koda2000]

O2 sensors can adversely effect fuel economy when they get too old, because they control fuel trims (and they don't always set the CEL). If you still have your original O2 sensors your at least 30,000 miles overdue for new ones. The ones after the Cats have no effect on fuel trims.

You seem to maintain your vehicle pretty well. From your description of recent maintenance I would not just start replacing parts willy-nilly, it's a waste of money.

If you want to check your fuel trims, a good ODBII tester will display this info, but heated O2 sensors are only good for around 200,000 miles.

 

[puzzaa]

yeah ill go get the codes pulled as soon as i have time to take it to my mechanic ( i dont own a scanner). And yeah fluids need to be done soon, as they are all original.

I'm not sure what the problem is with the fuel usage. the truck does just fine. besides the starting problem when its warm, it does fine. im not sure if its supposed to do this but on cold starts it idles at 1500 rpms then dips to 500 then back up and repeats until its warm. after a while itll get to about 750 which i think is normal idle rpm. the engine does fine, no odd noises or power drops when accelerating, very smooth. its sounds fine but i feel like its not putting down full power like what it used to do. maybe because its good days are behind it. i feel acceleration is a little slower im not really sure. engine does sound very odd after going past 65-70 mph (but i dont do that so i ignore it) the engine gets a lot louder and sounds like its maxing out. thats why i dont push this car too hard.

Also sounds like a wheel bearing is going bad because there is a noise when im rolling at 40mph (no throttle) but its only at that speed not when im going faster. but after noticing a squeaking noise when rolling (goes away when braking) i think my bad fuel maybe due to my braking system. i noticed my rear left brake rotor had rusted spots (like it wasnt making contact) while the rest of the rotors where shiny.

I pulled it off and noticed the back pad was all worn out and the front pad was in ok condition. i tested out the caliper and it looks like it wasnt squeezing like its supposed to ( it squeezes but doesnt go back open, takes a VERY long time ). i thought maybe it was the caliper pins so i replaced but still the same thing. so either i need a new caliper or brake fluid isnt getting to it? im not sure if that caliper could be holding me back while accelerating?? since it looks like its been worn out for a while i suspect another brake pad is making contact and causing the squeaking (unless its a bad wheel bearing causing it).

Hopefully its just these damn brakes and nothing serious (cant wait for the timing chains to break!). right now im riding around and i do feel like i slow down quicker then in my car but i just thought it was because these explorers werent designed to be aerodynamic and it weighs a lot more then my car. im not expecting your mpg numbers XLTrunner because of how low mine are. also when i changed the tires at 190k i think, i put on firestone transforce commercial truck tires. the guy did say it would reduce fuel economy a little bit but im not sure he meant 10mpg. but i do love these tires, very deep treads (more then my old Michelins) and a lot more grip in the snow and occational dirt/muddy roads. i will most likely be doing the intake gaskets because they are not as expensive and they are easy to get too (so many screws though!).

I suspect vacuum leaks because they are very popular contributors to bad mpg. there are so many hoses on this engine its hard to tell where to look. i read online somewhere that Fords are very popular for having hoses crack or start leaking but i didnt see any obvious cracks in the hoses. are there any popular spots where air could be getting in? i just want to cover everything to make sure its not something minor!

And yeah Koda I really dont want to put too much money into it because the good days of this truck are wayyy behind it. i just dont want to be wasting money in gas! i believe there are 2 o2 sensors before the cat converter or is it just one? i read up on o2 sensors and MAF sensors and how they affect fuel but theres a lot of other ones that could be doing it. any more advice would be helpful!

I know this is a lot of information, im sorry! but thanks for all your help!

 

[XLTrunner]

The erratic idle does seem to point to a vacuum leak. For comparison, mine will idle at around 1100 rpm at cold startup. Will settle down to around 550-600 within a minute...and, stay there. Upper/lower intake gaskets would certainly be suspect. While you have the intakes off, check your PCV valve and the hoses leading to/from it.