Yes i read all the threads but I need some help. I have a 1999 explorer sport with 86k miles on it. I did a huge tune up about 5k miles ago

oil change
new plugs
new wires
k&n filter
pcv valve
all new 02's
sea foamed
fuel filter

and then i got around 20-23 mpg. All the sudden and dropped and I was wondering why? What could have happened to cause this? Also what else can i do to improve mpg? I read cleanin out the throttle body, how do i do this. Thanks

After the tune up did you reset the computer? Could of gotten a bad/cracked plug that decide to go Tango Uniform (Ti_s Up) after awhile of being ran. I'm not a big fan of K&N drop in's, try KKM for a budget priced (but Good) air filtering system. Hope this helps, Good luck

So what are you getting now?

Lots of other things figure into it: weather, gas additives, etc.

Ammo so should i take out all my plugs and check them? And if i do what am i supposed to look for to see if they are messed up.

Alec i used to get about 21-23 mpg. Then all the sudden i dunno wtf happened , it dropped down to like 13-15 which is killing my wallet rite now u dont understand. I will kill for better gas milage. After the tune up for about 3 weeks it was like heaven then down hill

Any black smoke or rich smells from the tail pipe?

acually the other nite i noticed some smoke comin outta my exaust i figured it was jus steam but the car was warmed up. It didnt really smell tho so i dunno. What do u suggest

Maybe time for a new fuel pressure regulator.

But maybe first you should try cleaning the MAS and resetting the computer.

accually 2 days ago i recharged my k&n filter and cleaned the MAF sensor along with it. I always clean it when i recharge the filter.

So where is this fuel pressure regulator, how can i test if its bad and how much is a new one

Even though you changed the O2 sensors, I would hook up an OBD II scanner and monitor their function.

Did you do the work or did some mechanic?

i did the work, i do all my own work mainly cuz of money and i love doing stuff like this and i learn a lot while doing it.

Hook up a scanner and see whats going on.

Are you serous 13 - 15, I would kill for that my 1992 EX EB V6 4.0 gets about 10 - 11, but with 131, XXX can’t expect much. Do you have any suggestions? I have already changed the plugs, wires, regular oil change, and some Gunk fuel injector cleaner. Was going to maybe try some sea foam or have chamber flushed but not sure, was told this would hurt engine with high mileage, what do you guys think? I was also thinking about replacing the MAF but kind of pricey, just bought new cat, cat-back, front rotors and brakes pads so sort of short of funds at the moment. If I disconnect the battery will this reset the computer? How long should I leave disconnected? How will this affect alarm system with keyless entry and auto starter?

Thanks for any replies or suggestions. :us:
:redexp:

accually aldive my dad has a scanner but i have no idea in the world how to use it. hes a mechanic, well used to b and has all these tools and I jus try n learn on my own since hes never home. So how exactly would i hook this up. I know theres this thing under the dash on the driver side u hook it up to or something

you didn't seafoam the engine after you did the o2's did you?

also clean the maf and get some injector cleaner

but what do i do on this fuel pressure reg

accually i sea foamed my system 4 days ago... it says 02 sensor safe??

That might have screwed up the sensors.

well f#%#

SO how do i test if those are bad

and what about this fuel pressure reg

Test the O2 sensor function with an OBD II scanner.

how do i do this?

will the scanned say like "good' or bad or pop up with numbers and i gotta see if they are right or what.

Please don't take this wrong, but I think you need to have someone else do that.

well then can u jus tell me about the fuel pressure reg and what i should do with that

If the sensors check out, then it may be that the FPR is sticking, dumping too much fuel into the motor. The most reliable way of troubleshooting it is...to replace it.

But sounds like the seafoam messed up the sensors if your mileage grenaded after that.

I think i will just replace it. Maybe tomarrow Ill get some of my buddies who know a lot more about cars see if they can test em for me, if not i guess ill see how much a shop will do it for. Thanks a lot man for the help. If it is the sensors, do u know of bosch carries ne type of warrenty? I bought it from discount auto parts

you might be able to exchange the O2's for new ones saying they are defective

but how would i go about telling them that they are defective? Like i jus dont wanna go in and say "These are defective i need new ones." Whats some fancy lingo i can use on them lol

Well, tell them they Fubared a month after you installed them.