Horribly degraded performance

Yes by quite a bit.

But at least it was easy to replace. It also had a variable speed as it was driven from the Cam Shaft... The faster the engine ran the faster the pump pumped...

 

Are there currently any displayed codes?

 

The symptoms you describe are exactly the ones you get when the VVT solenoids start acting up. Cam timing goes whacky - typically they refuse to advance at lower rpm - and you get terrible acceleration, bucking, and general crappiness. Please don't overlook these in your testing.

And at least in my case, the problem did not cause any codes to appear. I chased the problem for a year before taking a shot in the dark and replaced them.

 

I have had no codes other than the lean bank 1 and 2 codes that haven't ever came back. It's been like 3 weeks since I've had a code.


I seriously considered the VVT solenoids. The only thing that deters me from that diagnosis is I have zero engine codes what so ever but I see what you mean. I just dont want to spend a million dollars on the truck taking shots but that would probably be one i might take.

Edit: I do have a higher or lower than normal voltage code through the ABS but I assumed that was when I put that 240 alternator on there.

 

www.urdusa.com for the fuel pump upgrade.

Cheaper, and then has a serviceable external fuel filter. If your pump is original, that filter is beyond saturated with contaminants.

Check all of the vacuum hose ends. There will be splits on most or all of them.

 

Yeah, glad he's back from his "carribean vacation".

 

I heard he was at banned camp. Never heard what instrument he plays though.... But yes, it's good that he's back.

 

Would it be easier to check the filters first? I don't know as I haven't had the, "pleasure" of dealing with something like this.

 

OP, kudos for reaching 330K miles but unfortunately, its gonna be a crapshoot on figuring this issue out. Although it could be fuel related, I would include ruling out some type of O2 sensor/ cat issue with that many miles. The reason for my guesstimate is because you did have codes temporary displaying sensor related issues and your issue did improve ,albeit temporarily, when you replaced the MAF and cleaned the TB. Add ruling out a partially clogged cat or maybe an air leak along the intake side.

 

I know I had someone say something about fuel trims. As you can see, the LT trims seem to be abnormally high. I'm not sure if this help my cause but they are definitely above +10 and will go all the way up to +20 driving on the highway and will shoot down to -20 letting off the gas.

 

I will probably replace every o2 sensor as a shot in the dark method. I'm guilty enough to say that I should have addressed this issue at the first sign of crappy performance but life gets in the way if you know what I mean.

 

I wish I could be of more help?
But other than guessing and trial and error. I’m with you.
I think anything -20% to +20 is with in range on FT.
Although I think closer to 0% is desired?

I don’t know if a lack of fuel pressure would would make the ECU go up on the fuel trim?
If it were very low on pressure! I would think it call for more + Trim than 14%?
But, like I said. I’m not a mechanic. Am at best an ok parts changer. And that’s on a good day.

Maybe the other guys that know much more than me will give you more advice?

 

They go hand in hand. Always do both.

 

A few years ago I did a tune up on my dad's 2nd gen and after 6-8 months it started acting up, lack of power, bad milage, rough acceleration, but no check engine light. Long story short, I pulled out one of the plugs to just check and it looked like crap, what ever plugs I got from the parts store the engine didn't like. Went down to the dealership and picked up a OEM set of plugs and it was back to its previous glory.

 

From what I read, the change out of the MAF made the crappiness go away temporarily until it came back again. If the fuel pump is the issue, wouldn't the severity of the symptoms remain consistent regardless whether the MAF was changed out or not? I don't have a solution, but just a thought that came to mind. Maybe I'm incorrect on how this works.

 

Considering what you just said, I heard that if the fuel pump is going bad the bad performance is somewhat inconsistent. That's the issue I'm dealing with. Maybe 1 out of 10 times my vehicle runs like it is completely normal and that's what makes me fall onto the fuel pump. Maybe I'm completely wrong as well.

 

Now that's something to think about. I did put copper core plugs in my truck instead of the factory iridium plugs and here I am so and so months later running like crap.

 

I think you need to test the pressure while driving.
I think @Bishop84 is a Toyota Technician.
I’d take His, JimmyH, or Muddinfun advice first.
They seem to be the 2nd Gen gurus here.

 

The 4.0 have Copper Core from the factory. Denso and Bosh
The 2.7 had Iridium.

 

Gotcha. I hope it is as straightforward as the fuel pump and you can move on to the next couple hundred thousand miles.