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can not accelerate past 40

sothisisit

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October 6, 2014
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Year, Model & Trim Level
2004 Explorer XLS
hey

new here. just bought a 4.0L 2004 Explorer XLS.

I am having an issue tho.

when I am driving it has A LOT of lag. getting to 40 KPH is hard but then gets worse from 40-60.

I have had a scanner done (engine light IS on) and it pulled a ton of codes. including O2 sensors and intake air temp issues.....

reading through google i have seen that the o2 sensor isnt likely the issue. and I have tried cleaning the Throttle body and MAF sensor (which apparently contains the IAT sensor).

I have also disconnected the front drivers side o2 sensor ( which helped a little). tried to get at the front passenger side one, but cant reach the harness.


Any Advice? this is really starting to get at me.
 



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hey

new here. just bought a 4.0L 2004 Explorer XLS.

I am having an issue tho.

when I am driving it has A LOT of lag. getting to 40 KPH is hard but then gets worse from 40-60.

I have had a scanner done (engine light IS on) and it pulled a ton of codes. including O2 sensors and intake air temp issues.....

reading through google i have seen that the o2 sensor isnt likely the issue. and I have tried cleaning the Throttle body and MAF sensor (which apparently contains the IAT sensor).

I have also disconnected the front drivers side o2 sensor ( which helped a little). tried to get at the front passenger side one, but cant reach the harness.


Any Advice? this is really starting to get at me.

Is it just running really rough at higher speeds??

Because at first glance it looks like a transmission problem more than engine..

any O/D light flashing?
 






Once the trottle seems to kick in it shifts gears smoothly. shifts in and out of P N R D smooth as well... no O/D light.

the acceleration is very slow. esp on hills or inclines. this morning on the way to work, it went from like 50 to 20 on a hill and just hovered there....

also i have noticed. if i feather the gas its fine. as soon as i try to open it up. and push the pedal down, it seems to cut out after it is approx 1/4 of the way to the floor


idles fine. doesnt chug or no loud noises
 






Once the trottle seems to kick in it shifts gears smoothly. shifts in and out of P N R D smooth as well... no O/D light.

the acceleration is very slow. esp on hills or inclines. this morning on the way to work, it went from like 50 to 20 on a hill and just hovered there....

also i have noticed. if i feather the gas its fine. as soon as i try to open it up. and push the pedal down, it seems to cut out after it is approx 1/4 of the way to the floor


idles fine. doesnt chug or no loud noises

Throttle positioning sensor? Idle air control valve?? I am not a mechanic by any means. I've owned 22 fords over the years and fixed a variety of issues, this hasn't come up in my limited experience. Hope someone chimes in more knowledgeable.
 






I would check the fuel pressure under a load first. A plugged fuel filter can cause some very noticeable drivability problems. Clogged catalytic converters can cause the same symptoms. You can check for clogged converters easily with a vacuum gauge.
 






Yup, make sure a clogged CAT isn't the issue because it kind of sounds like it. No rattling or weird sounds coming from the CAT?
 






I second the clogged cat.
 






I ran into a collapsed exhaust pipe on mine. After Ford dealership tried to fix it, a friend of a friend, told me to take it to a retired Ford tech who did side work out of his home garage. It took 15 mins. to cut the exhaust pipe behind the cat. and found that the pipe had collapsed. A case of beer and a hand shake was the cost. Too bad he has passed away, he taught me a lot.
 






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