2008 Tundra has lost power? Detailed description of issue to help as much as possible.

Hello everyone, I've been having this issue with the truck for a little over a month now and was hoping to hear if any of you all had any idea of what is going on.

So the current issue is that the truck has lost its low end torque. The best way I would describe it is that I have to push the gas pedal farther down and get higher into the rpms to get the car to accelerate than I normally have to. So for example, I would usually be able to accelerate the vehicle at about 1k to 1.2k rpms but now I HAVE to get up to 1.5k rpms with the truck jumping easily to 2k just to get some momentum going. Additionally, if I am doing down the road at 45 mph or whatever other speed, if I take my foot off of the gas, the truck doesn't just slowly decelerate as normal, but it noticeably loses momentum as if there is a minor cut of power or something. The strange part is that when it first started, it was really bad, where it felt like the truck had very little power and it took forever just to get up to 45 mph, even with the pedal pressed very far down. Actually, the part that makes all of this even more strange is that the truck when from totally normal to really bad from one moment to the next under normal driving conditions.

Besides the trucks behavior, it was doing several warning lights. It was doing the check engine light, the vsc off light blinking, and the traction control light on, but they were only on for like 20 minutes and then they turned off. After looking online, I thought that maybe it was just bad gas or something so I used the rest of the tank, refilled it and got only a slightly improved performance. After that, I decided to go ahead and pop open the hood and change the air filter, clean the throttle body, and clean the MAF. That slightly improved things, but it hasn't gotten any better than that.

Since then, I've gotten 4 new tanks of gas since the issue started and have gotten it checked by a local mechanic but said they wouldn't be able to diagnose anything since there are no check lights or codes coming up on the scan tool they used. I use the truck as a daily driver and am still able to use it fairly well, it's just that I know something is wrong since the truck still takes a while to get up to speed and maintains its speed very well, but not perfectly normal.

I've looked around forum sites trying to see if I could find any information about this but I couldn't find any good information that would help. I apologize for the length, but I just really wanted to get this out there. Thank you in advance for any guidance I may receive!

 

I'd start by reading the CEL codes, set or pending. If none, I'd clean the MAF, IAC and intake plenum.

 

I cleaned the MAF and changed the engine air filter a couple weeks back and while the air filter needed to be replaced, the MAF was actually pretty clean. As for the IAC and Intake Plenum, are those difficult parts to remove and inspect?

edit: Also, I have taken it to the auto part store to get the light checked and nothing comes up on their machine. And the auto repair shop recommended that we just bring the truck back when it shows the check engine lights again since they didnt see anything wrong but it never did show the CEL again.

 

Ok, so I know I've seen a post around here somewhere about diagnosing an AIP failure so I guess that's something I can look into since I didn't think of that before. And the transmission feels fine to me at least. I'm not exactly sure if there's a way to tell an engine problem from a transmission problem, but it really does feel like the transmission is doing it's best with the input that the engine is giving it. So I'm still able to control the shifting at certain speeds as I normally can, it just takes longer to get to those mph marks.

 

I’d try disconnecting the battery, press the horn to remove residual charge, then wait a half hour or so to “reset” all the computers in the truck and see what happens. Almost sounds like it went into limp mode and then “went out of it” but really didn’t. Interested to hear what happens

 

I'll definitely try this tomorrow. I have tried unplugging and reconnecting the battery before but not for an extended period of time like that.

 

I’m a “try the super simple and free or cheap” options first kinda guy. Some other forum posts suggest the fuel pump may be going bad causing the “bog” under load. Perhaps a fuel pressure test under driving load is in order?


https://www.tundras.com/threads/4-7-liter-loosing-power-and-surging-during-hard-acceleration.58354/

Also some others have suggested running several tanks with Techron fuel system / injector cleaner to see if maybe it’s an injector problem.

Also how many miles are on your truck? Maybe a coil pack is going bad? Tried to do some Google searching to find potential problems but other than what I’ve found, not sure what could be next. Interested to hear if you get it sorted

 

I put a fuel injector cleaner every once in a while, like every 40k or so, since I know the truck doesn't have a fuel filter like some other trucks out there. I'll probably just get a bottle tomorrow just to see if it helps any. And the truck is at 125k at the moment and was a 2008 model year, so I suppose it's possible the coil packs could be bad. I'll look into how to go about getting a fuel pressure test and testing out the coils since I've never done or gotten something like that done before but I will definitely be putting any updates here on this thread.

The only other thing I could say about my situation versus those other two threads you linked is that my engine is just consistently weak all of the time. Whether I'm navigating a parking lot or cruising down the freeway, I feel the same proportional lack of power for the situation. Thank you for those links by the way!

 

Have you checked to see if your brakes are sticking ?

 

The loss of power symptoms sound exactly like my 2007 when the AIP went to crap. Let us know what the battery disconnect does for ya....that's how I got mine out of limp mode momentarily to get it home & install an AIP bypass kit.