Truck seems to lack power

Hi everyone. I just bought my first Tacoma, it is a red 2002 extended cab 4x4 with an automatic transmission. It has 129,000 miles and 3.4 V6 engine. My problem is that it really feels like it doesn’t have a lot power. Around town it seems ok, but nothing impressive. The real kicker is on the highway. It seems like it struggles to maintain 70 mph, especially uphill. I have done a myriad of small improvements, and it seems just slightly better than the day I drove it home. I don’t know if this is just how Tacomas are, or if just a symptom of a 20 year old truck, or if something is wrong with it. (For the last ten years I’ve been driving a 2011 Cruze 1.8 liter and that’s all I really have to compare acceleration to.) When I bought it, the check engine light was on for the downstream 02 sensor. I replaced that and the light went off and hasn’t returned. The oil looks fresh and trans fluid looks nice and clear. As for other improvements, I ran a can of seafoam, replaced the throttle position sensor, removed and cleaned the MAF sensor, removed and cleaned the throttle body, replaced all the spark plugs, replaced the air filter, and replaced the muffler (but not the cat). Also the cruise control doesn’t work. The light comes on but otherwise won’t engage. I’ve seen a ton of posts for this, but they all seem related to the manual trans clutch switch. I don’t know if the cruise problem could be related to the acceleration/power issue in any way. So, I’m kinda at the end of my skill-set-rope here, and just nosing around to see if hopefully you guys can suggest some other simple things I could check or replace that would affect power output. I’m no mechanic, just mildly mechanically inclined. Thanks for your input.

 

I think you'd have to drive another truck to really get a butt dyno on whether or not you're missing power.

Have you inspected or considered any fuel system maintenance? Specifically the fuel filter and injectors.

 

Yes, I’m sorry I forgot to mention that I replaced the fuel filter. I have not done anything with the injectors though.

 

Nice looking truck, and as the other poster said, you really need to compare it to another. They arent a fireball at the best of times. They are a little harsh in the upper rpm ranges and to get it moving good, you have to get it up to the upper ranges.

 

Ok thanks! Makes me feel a little better about it. I love it otherwise so far. It’s nice and easy to work on.

 

do a compression test, hard shifts? slippage?

 

You mentioned you changed the plugs, but what about the wires? These engines run noticeably bad when the wires get old.

 

The lack of cruise could be a clue. I've had vehicles in the past with a failing brake light switch that would prevent cruise from working - and also prevent the torque converter from locking up. Might not feel super slow, but it would kill your hwy gas milage.

Other than its kinda hard to tell without some objective measurements of the state of the vehicle. I know my 4 cylinder has no problem maintaining 70 on the highway, so i would be surprised if a 6 cylinder couldn't do that. Then again if you were at high altitude maybe not.

How is the gas milage?

 

Ok so, no I didn’t do the wires, but I will. Thanks. I also did not do a compression test. The transmission seems to shift fine. Definitely a harder shift than the Cruze but does not seem extraordinarily hard or anything, and no slippage. I just reset my “trip a“ to zero so I’ll get a more accurate mileage soon, but I think I’m getting 13 mpg or so. My job is 60 miles one way. I’ve only taken the truck once, before all the repairs, and round trip took half tank.

 

What you bought is sort of a novelty truck.....
Its a high profile truck adapted from international Hi-lux's and 4 runners back in late 80's....
And these are not unibody crap, like new jeeps ect....these are heavy duty frames...

Rz and Vz engines are not updated 22r's ......they go back to late 50's and early 60's....
so they are not very efficient......but can last forever......modeled after farm engines....


Alot of people surprise how little hp these have....
Highway cruisers and commuters might do better and get same mileage with same year Tundra with the 4.7......
You just wont be the cool guy on the weekend.....


Super good lookin truck.....there might be V8 tundra guy trade you even......that is if all you want is a commuter to run it to death....

If my math is good......thats 30K a year....

 

1/2 a tank to go 60 miles is... horrible. Something is way off if that's true. I'm not sure where to suggest starting. Checking the general health of the motor... Then I guess checking some of the driveline- u joints, bearings, and brakes, to make sure there is not excessive drag.

 

He said 60 one way, so 120 on half a tank

 

Momentum is big. Taking hills the right way helps a lot. Seeing as you’re auto, for the next sustained hill turn OD off and let the RPMs climb. You’ll keep power much better and keep your transmission cooler. Turn OD back on at the crest of the hill.

How tight is your driveline? Look for places you are losing power between the crank and the rear wheels. ECT is noticeable to me but others aren’t convinced. I leave my ECT on almost always.

Lastly, is your right foot possibly not up to the task…? Lol

 

Check for stored or pending codes, and also monitor fuel trims if you can. It sounds like it might be in limp mode, possibly due to bad knock sensors, or less likely, a bad ECM or some wiring issue. I'm still dealing with a similar issue in mine.

 

I’m hoping it’s not limp mode - wouldn’t that be extremely obviously underpowered? If he’s complaining about not maintaining 70 up a hill, I highly doubt he’s in limp mode.

 

I think it just cuts power by 20% or so by retarding the timing. It's not like the limp mode in a modern diesel where it makes you go 30 mph.

 

You're more mechanically inclined than you let on. I can see that. From the looks of it, you have something worth fixing and keeping.
I have the 3.4 v6 5-spd and I get 17mpg. I've removed the steel shields under the truck and put smaller tires on 10 years ago. I can hold 70mph uphill but my foot better be on it before and during.

13mpg is pretty bad. I'll bet there's something wrong. I suppose the wires are worth a try.

I have 2 new O2 sensors coming just because 23yo and 145,000 miles. They are original. You could put the upstream O2 sensor on the list.

Denso 234-9001 upstream O2 sensor 3.4 v6 automatic
https://densoautoparts.com/find-my-part.aspx