Low Power and Engine Noise...

2001 Tacoma DC 3.4l 4x4 Auto..... Lately i'm noticing that the truck has been really under powered. I have a hard time even maintaining my speed on relatively flat ground on the freeway without taking it out of overdrive. Fuel consumtion has decreased a bit also. Just driving around town, acceleration seems to feel really sluggish too. while driving down the road, i can hear the engine is a lot louder than usual. when you let off the throttle all the noise is gone. once back on the throttle the noise is back and the noise doesnt change with heavy or light load on the engine. Its just there as soon as the accelerator is pressed enough to keep me from slowing down. The plugs were done 20k miles ago along with all new belts, idlers, timing belt, and tensioner. I thought i might have a problem with a Cat so i removed the cats and make sure they weren't plugged. i could see through them both. I'm not sure what else to check for at this point. im about to take the front end apart and double check that everything is still in time... .Any suggestions? Thanks in advance...

 

When was the last time you checked the air filter? Have you cleaned your MAF sensor lately? Do you have a K&N or gauze type air filter?

 

air filter was changed about 5000 miles ago. i have not thought to try cleaning the MAF.. i'll give that a shot

 

Have you had any luck with this?
I purchased a wrecked 2001 about 4 months ago and I just got it on the road.
Im troubleshooting a problem now that sounds similar to yours.

when I try to go above 3000 rpm it hangs up and wont shift.
I don't think its transmission related as it will shift smooth when not under a load.

I believe it is fuel related.

 

have you guys replaced your fuel filters? do the simple stuff first before getting into other stuff

 

Describe the noise in more detail please.

 

Also, just a thought, not an expert in any of this but maybe see if your cats are clogged or maybe just one is clogged? That would cut your power and make the engine sound louder. Easy test would be for someone to start your truck and get them to give it some gas and put your hand by the tailpipe and see if it is exhausting like it normally does or is very little coming out.

 

@keakar
Doing the fuel filter tonight.
only had it on the road a couple of days.
changed air filter, oil, Spark plugs, Plug wires.

Has anyone heard of any Pro's & Con's about changing Transmission filters on a high mileage auto transmission.
Its shifting fine and the fluid looks fairly clean, seriously doubt its ever been changed. I have just heard horror stories about changing filters on a tranny
can be just as harmful as helpful.

 

How's the condition of the vacuum hoses?

 

OP hasn't responded yet so not sure with his.

@NF2001Yota the filter change is fairly easy, it just bolts up. If the fluid is clean/good then it shouldn't be that. if it's crimson/brownish then it may be time to change. if/when you take the old filter out examine it to see if any of the filter is missing, could be an indication of clogging.

also check for exhaust leaks around the manifolds and see if anything is leaking around the heads, could be worn/bad gaskets.

 

@frizzman Thank you for the insight. very helpful.

I took it to Toyota today to get a diagnostic's done on the whole truck so I know exactly what im up against.
They came back with the transmission being shot and front differential being shot as well.

It shifts fine if you don't stab in it, pretty much keep it under 3500.
When you get it above 3500 rpms that's when it wont shift, it will hang in a gear.
I am no transmission mechanic but I feel like that would be a shift module of some sort if there is one.
Any insight or direction would be greatly appreciated.


Also trying to figure out what year differential's will fit in the 2001.
Does anyone have any insight on determining what year vehicle parts are compatible with one another?

I found a used 94 front differential. Just from glance, they look like they will match up.

Did not mean to jack your post @BCollett looking for all the help I can get.

Thanks agian

 

to keep things matched up 95.5-04 is the same "model" just have to make sure you get the same diff as the one you have. gear ratio matters too unless you feel like swapping them out.

 

Ok Thanks.
the 94 has 4:10 gears in it.
I just need to do some research on whats in mine.

 

I took my Truck to Aamco for a diagnostics and got lucky with it being a honest one.
They came back with it not being a transmission problem that the tranny is sound.

They say its a motor problem.

I Changed the fuel filter, air filter, oil, plugs, plug wires & the transmission filter.

"Toyota"told me the tranny was shot that it wasn't the motor before I took it to Aamco.

I drove it last night after changing filter, when you keep it below 3 grand its fine.
You go to step in it or try to run through the gears it hangs at each one.

I need some help, I cannot figure it out to save my life.

Any and insight is welcomed.

I am going to try and check out the Throttle cable tonight.

@frizzman @keakar do you guys have any recommendations?

 

my fuel economy has magically gotten better without me doing anything special to the truck but i still have the loud noise that isn't normal. Cats are not plugged. i removed them both and inspected. i ran the truck without the muffler and even over the loud exhaust noise i could still hear the engine noise so its not the muffler that's bad either. all filters are new fuel included. I've decided i'm going to live with it for now. what ever it is its not bad enough to be obvious so i'm at the point now where i'm just going to run with it as is and hope that it doesn't become a problem that will leave me stranded one day.

 

@BCollett I was able to pin point my issue over the weekend.
Its the knock Sensors. Fuel economy is about 10MPG. Might want to check those on yours if you haven't already.
Im hopefully going to dive into those this week.

 

@BCollett if you cleaned anything it may have taken time to re-calibrate. usually pull the EFI fuse and disconnect the battery to let it re-learn.

@NF2001Yota edit: you posted as I was typing, glad you figured it out