Need some advice

[markNtennessee]

I have a 2001 Expy 5.4l 4wd with about 160,000 on the clock, its stock except for the breather box has been cut and a K&N filter installed. I changed the spark plugs about 6-8 months ago, using NGK platium plugs. The coil packs looks to be factory, all of them are matching motorcraft brand. I also replaced the fuel filter around the same time as plugs, i have checked the elbow on the back of the intake that is mentioned on the forums, but the truck just seems very sluggish at times, almost like its being help back and not wanting to go. It does this at various time, not just from take off or passing on the interstate. Also when im pulling a small lightweight 14' trailer with about 800 pounds loaded on it and accelerating up a hill, it just dont want to go at all. now i have only had this truck for about a year, but im really disappointed in the power of the engine. previously i owned a nissan frontier 4wd and it had 180 horse engine and that truck seemed to have alot more power than this expy. I realize that the expy weighs more, but you would think that it would have a little more get up and go to it.

the expy has no CEL or any type of stored codes, indicating that there is a problem with it. It does seems to have a very slight miss to it at idle. I dont know whether to do a tranny flush to it, cause of the milage, and i dont know if the previous owner ever had it changed. So what are your ideas on whats making my expy perform so poorly?

 

[bring_em_on]

Best place to start would be with the coils (you don't have to go with factory coils...they are too expensive). I would replace them all and see what happens. And a tranny flush would be in order as well. While you're doing the tranny flush, may as well change out the differential oil and service the transfer case. Are there any knocks coming from the engine?

Do you know the previous owner? I mean can you verify his service habits? If you're not sure about how well it was taken care of, then you might want to have the oil system flushed to get out any gunk build up. All it takes is a little bit of gunk to clog up the oil passages in the cam or phasers and cause some major problems.

If changing the coils doesn't work, then you may want to have a compression and leak down test run on it.

Hope this helps ya out.

 

[seeker]

I agree with looking into the coils. I have had the same thing happen twice. The coils will make a hesitation or sluggish feel and not throw a code. It is very frustrating. If you have the time buy one coil. Start at one point and work you way around switching the new coil to different cylinders to see if you can isolate the bad coil. I really would not replace all the coils at one time unless you have the cash to burn.

It is always wise to service the trans if there is a question of service history.

Check the exhaust system for a cat that may be plugged up.

Also consider a Gott mod if the k&n system is still pulling air from the fender. Ten bucks and a hour of work. The throttle response is great.

 

[markNtennessee]

I have heard horror stories about changing the tranny fluid on a high milage vehicle if it hasnt been changed on a regular basis in the past. About 10 years ago, i bought a toyota 4Runner and it had around 140,000 on it and i had all the fluids serviced and changed and not long after that my transmission started slipping and the transmission shop told me that it was due to me flushing the system and it washed all the debris down and clogged up passages.

My airbox doesnt suck air from the fender, its completely open. you can open the hood and see the entire filter. Now i have wondered about that mod, cause i think it would be sucking hot air from the engine bay, with the setup i have now.

 

[2blackfordrides]

I agree with the coils.... They are typically expensive (45 from autozone and 80 from ford) but i found a ebay store that has all 8 with a lifetime warranty for 85 shipped..... Even if they dont warranty them when they go bad( and they will go bad....)..... For the price of 2 coils i got all 8 ( with motorcraft part number on them and they match the one from autozone perfectly)...... Also i bought new plugs and fuel filter..... Mine was doing the same and i had just replaced my tranny myself...... In the last 5 weeks hasent thrown a cel... So i used my code reader ne ways and there was a pending code( no cel but almost)... Which was for cylinder 2 misfire.... I replaced that coil and what a difference.... Its like the truck is completely different... I didnt do the plugs or the other coils cuz i wont lie im a lil scared of blowing a plug.... So imma take it to my buddys shop who warrantys the work and have him install my parts...... Still a few hundred less than just buyin the coils myself from store and not even including labor.... And as far as the air filter i would try cleaning it... But be careful not to use too much oil as u will mess up ur maf sensor... Or go back to stock ( with either a k&n or paper filter) and do the gotts mod.... I was really skeptical but its been dynoed to get u over 7hp and it gets me better mpg/throttle response.... 2 thumbs up from this guy for the gotts modd.... Idk of ne other mod u can get those gains for 13 dollars.....
just my .02cents

 

[markNtennessee]

I think i will start off with flushing the transmission.. Any suggestions on the best way to get all the old fluid out and what should i use to flush the system? I really cant afford to take it any where and have it done, and also i would prefer to do it myself.

 

[2blackfordrides]

I would contact kwt2000 on here... He was a life saver when i was replacing my trans... Giving me all the info i could need.... Not sure of the best way to flush it and he has alot more experience with these trannys than i do.... Give him a try.... He def knows his stuff....