Lack of Power

Ok so my 2003 2.7 doesn't like cold or damp mornings anymore and I don't know why anymore. Ive been scratching my head on this for months. Took it to a mechanic to see if he could figure out what was wrong with it and it didn't throw any codes. Ive replaced the spark plugs, ignition coils, fuel filter and attempted to change the MAF sensor but the truck rejected it despite my many attempts, just wouldn't take it ran like shit or not at all. Any ideas anybody? Truck just picks and chooses what days it runs right, likes to bog down on an ant hill even after its had time to warm up.

 

Also my truck has 130k on it if that help diagnosing it.

 

Does it lack power at all RPM's? Just when taking off, or at all speeds? Manual or Automatic transmission? Does it run fine at idle, skip or miss at all that you can hear, or does it miss when you get onto the gas? Do they have to be cold AND damp, or does just cold or just damp cause the problem as well? Does the problem get better, worse, or go away once the truck is warmed up?
Have you noticed a drop in MPG's lately?
Also, do you run your defroster at all on warmer days, when the truck isn't having issues?

 

The problem mainly is at acceleration and from then on it just bogs down on hills. The problem is on both cold and damp days. The problem seems to show itself mainly at around 2,000 rpm my normal cruising rpm then bogs down and will usually downshift. The problem gets a little better after its warmed up but hills are still an issue. I haven't noticed any drop in mpg and yes I run the defroster every morning. I preciate the help guys sorry it took so long to get back to yall.

 

Mine does that too.. 96 2.4L auto tranny with 170k. It sucks man, i thought about cleaning out my intake and everything but i doubt it'd do much. PM me if you get any info on it

 

Could be one of the sensors is going bad. Lots of them on the truck, and they all tell a story to the ECM, and it reacts to it.

Find out what the resistance values are supposed to be and check as many as you can.

 

Yeah thanks for the input guys. I keep coming around to the same conclusion that I just have to start replacing sensors one at a time. I think ill just about have a whole new engine before this is all over. Gonna try replacing one of the O2 sensors next then I guess the fuel pump.

 

Im open for suggestions if anybody has any. Im not made of money so if somebody can point me in the right direction that would be great.

 

So does it seem to idle good all the time? If its just when your driving it pulling hills etc sounds like it could be transmission related?..

 

Check your injectors.. Im pointing toward that or you could start to have a fuel pump going bad not pumping enough fuel to the engine or it can be the fuel regulator could be bad..


Edit this could also be a sensor dropping out on you like your MAF or cam sensor... Only way to correct check those is with a lab scope..

 

It idles great. Wasn't sure if it might be the injectors? Do you reccamend a good cleaning or replacement? I also have considered the transmission because it being an auto. Do the autos have any bugs Im not aware of?

 

Same, idles great, but bogs for a few miles. its fine when it's warmed up but i don't like how it reacts at the beginning.

 

Before you worry about pumps and injectors, have you ever replaced your fuel filter? When was the last time you replaced your air filter? Also, at the risk of sounding obvious, have you checked the fluid level in your transmission?

 

The fuel filter is brand new. Since you brought up the transmission fluid I will give that a check since I don't check it too often. I did replace the fluid about 30k miles ago and checked it a few times since. Would a clogged transmission filter possibly cause my problems?

 

Oh, right. You mentioned fuel filter in the first post, I just missed it. Whoops.

Every clogged transmission filter I've seen has resulted in hard shifting, not in a lack of power. I suppose it's theoretically possible that it could cause a lack of power...
Usually it causes transmission slipping or hard shifting, though.

 

It is temp related it sounds like so change your air temp sensor located in your air filter box. Its about $20 at your local auto parts store and doesnt hurt to change if its isnt the culprit.

 

Any luck OP?

 

Ok ill look into that air temp sensor. The truck just has a mind of its on it seems. I appreciate the help guys. Im just gonna continue changing sensor like ive been doing and hope I hit the right one. My friend has a Honda crv that had an O2 sensor go bad on his car that had some similar symptoms so maybe ill start with it.

 

Does anyone know why my truck wouldn't take a new MAF sensor? Tried every trick that I could come up with and my truck just ran rough or not at all. Im thinking this could be a problem indicator or a crappy new sensor??

 

I would clean the O2 sensor before actually buying one, no sense in throwing parts at it if you don't know the real problem. You should take it to the dealer and have them run it with their scanners to help pin point the problem.