Random loss of power, shifting, and acceleration

I'm having an issue with power loss in my Tacoma. I started it up a few days ago, and when I tried to accelerate, the RPM's stayed at 1000, and the top MPH was 10. I floored it, it sputtered and rolled on at 10 MPH. I pulled over and let it run for a few. When I tried to drive it again, I got 1 1/2 RPM's and 15 MPH. Finally after about 15 minutes, it started to rev up, and accelerate above 20 MPH. It wasn't shifting gears at 3 RPM's, and stayed at 60 MPH. It wasn't down shifting either. An hour later, nothing seemed to be wrong, it was driving and accelerating fine.

I took it for a test drive the other day and went to drive up a gradual incline. On the way it was shifting, accelerating, and revving strong. Different story when I got it going up hill. The RPM's dropped and it felt like a total loss of power to the engine. I tried to put it in the lower gears, floored it, and all I got in response was more sputtering and loss of power.

When I turned around and went back down hill I shifted it again, and everything worked. The lower gears down shifted, OD was good, and there was power. When I went back up the hill, the same thing as before happened. I tried this 4 times all with the same response.

On the way home, and at a level surface, the truck ran strong, accelerating, and shifting normally. So in my conclusion, the engine is strong and the transmission still seems to be "working".
The check engine light is on. The codes are for 02 and Mass Air Flow censors.

WTF is going on? I'm taking it in to a mechanic tomorrow, but any insight as to what I could be looking at would be helpful.

 

Sounds like a loose connection to your MAF, which may have led to an overly rich condition. Your codes are likely right on.

Flash

 

if thats the codes you got then thats the best place to start. but before buying a new MAF or o2 sensors inspect them first they may just have some serious build up and can be cleaned if so.

 

Pwr loss on acceleration from dead stop. Still under warrantee but Toyota says they cannot fix it if no eng ck lite. Repeatedly building my case for Colorado Lemon law if it is not fixed. Met w/Toyota Rep and test drove but this problem is intermittent. I get up to 10-20 mph and then nothing for 3/4 second; push gas pedal all the way to floor and when it starts-up it starts up slowly. I also called the factory 800 # to get a number assigned for problem and I asked for this number to B classified as a safety issue. I can no longer "risk" trying to merge onto main traffic unless I have 3-times the normal distance for entering traffic because of problem. I have documented 8 pwr losses to date for a truck I purchased Oct 2011.

 

Hi crow2012! How your case ended up? I'm having a similar behavior on a 2011 228000 K.

Thanks!

 

You could try cleaning the MAF with the "MAF sensor cleaner" that they sell at the autoparts stores. Sounds really weird. I'm thinking an unclean or failing MAF based on your description. An O2 sensor is maybe, but I've never heard of them really having such a drastic effect. If you do decide to replace the MAF, I know that the Hitachi brand makes a true OEM part for it.

 

year and motor size please.

 

Hi crazytacoman. I’ve red most of the topics on this kind of behavior. Mine have now DTC P0171 as well as P0174 system too lean codes. I’ll start with the recommended solutions:
1.Look for leaks on the air intake system.
2.ask a mechanic to review the fuel trim response
3. review MAF sensor condition
I also red a topic related to this talking about the OCV filters having some relation to this.
I’ll start to dive into these diagnosis.

 

Hello Glamisman. Year is 2011, motor is a 4.0 liters.

 

Check these out:

https://www.tacomaworld.com/threads/lean-in-both-banks-p0171-and-p0174-solved.699008/

https://www.tacomaworld.com/threads/p0171-solved-finally.330233/

 

Thanks!!

 

you might get more responces in the proper Tacoma year forum.

 

Thanks Glamisman. I’ll take a look to it.