Horribly degraded performance

I would just like to say that i appreciate every single one of you for the advice you have given me in an attempt to diagnose this issue. I have narrowed it down to several possible issues and it seems to be a fuel issue or some kind of sensor issue. What I will probably end up doing is replacing the fuel pump regardless if its bad or not considering the truck is well over 300k miles. If it isn't the issue, it will at least give me a firm ground to stand on and far as me knowing that i am getting adequate fuel pressure. Another reason I am going without testing is that many people have suggested fuel pump it will either be the fuel pump or o2 senors that will go first. That is the trouble I am having as well. I realize the truck has many many miles and it can really be anything at this point. I know for a fact that the o2 sensors, fuel pump, VVT solenoids, and injectors are all original on that truck and I am not sure if i should just wing it and go down the line replacing parts or if I should keep busting my hind end on a bulls-eye diagnosis.

 

Thanks!

I needed time off for the Hurricane anyways :shrug:

 

Check all vacuum hoses first. Free.Then fuel pump and filter. Filter is not accepting any more visitors. Needs replacement. Then worry about injectors. Clean or add new to regain proper atomization.

 

Of course. I was thinking more along the lines of the condition of the filters being an indicator of the condition of the ocv. They are also easier to get to if I'm not mistaken.

 

That was a crazy hurricane. It was initially a Category V4 hurricane, then it was in the process of upgrading to a Category V6. It affected many lives of those directly involved but the main EYE of the storm ended up affecting and temporarily closing a neighborhood library. There were hundreds of books with diagrams floating throughout the neighborhood but fortunately, I heard that none was lost and the library is now open.

 

You mentioned throttle body cleaning. If you did that without removing it a couple of different things could have happened. You could have contaminated the idle control and the air fuel sensor. I would start with replacing air/fuel sensor and o2 sensors. The air/fuel and o2 sensors degrade and significantly effect performance and MPG. This was magnified if you did a throttle body cleaning without remove it to clean it. Good luck.

 

^^^ Wrong.

 

I would remove a throttle body to clean in order to have better access to the entire device, but I'm not sure I follow the "contaminated idle control and the air fuel sensor" comment.

If you are inferring there is an idle control vale - there isn't on the V6 1GR-FE. The engine is drive-by-wire - no mechanical linkage. I would agree that if you were to blast away with Throttle Body Cleaner, you could damage Throttle Body electronics. You lose me with the air fuel sensor comment. I would not indiscriminately replace the upstream/downstream sensors until scanner trim value readings and/or voltage test told me they were bad.

 

I did do a voltage check on the o2 sensors through a diagnostic tool. I forgot what bank it was and which sensor but it was after the throttle body cleaning and the voltage was really high. Like 3.5 to 4.0 volts high. I then assumed it the o2 sensor. I did disconnect the battery first and and the voltage went back into the normal range.

 

Have you ever ran fuel system cleaner before?

 

I have ran it through a time or two. Never really noticed a difference probably due to my inconsistency.

 

This was my first thought. I have a 2009 DCSB with 275k miles and still running strong. I hope to hear a solution to for future reference (knock on wood).

 

I wouldn’t hurt to get a cheap bore scope and look down each cylinder. Did you buy the truck used? If your the original owner kudos to you.

 

Does anyone know of a fuel pump pressure tester that will fit a Tacoma.

 

I've changed out many pumps on guys' trucks, at only 100k. Picked back up a very noticeable amount of lost whp. Worthy investment.

 

www.urdusa.com. They have a fuel rail adapter for a pressure gauge.

 

https://www.urdusa.com/urd-fuel-rail-tap/

 

So I spend about $100 to get a master fuel pressure kit from harbor freight and turn out this is my pressure at idle. I didnt bother to drive with it because it was kind of a dead give away. Its low compared to specs. The highest it got was to about 32 psi. Spec calls for around 41 or 42 psi so I'm wonder will 10 or so lower psi really be giving me issues as described?

 

Your test shows 25% less pressure than it should be.
Did you preform the test with engine running?
I believe it is to be tested with the ignition in the “on” position.
Doesn’t say anything about engine running. That is why I ask.


There are 2 other thing between the pump and injectors.
The Fuel Pulsation Damper and the Fuel Pressure Regulator.
I have no idea what those 2 do when they go “bad”.
Do they fail to “high pressure” or “low pressure”?

I’m still going with Fuel Pump.

 

I did do it with the engine running. I tried just the "on" position but wasnt getting any readings until I started to turn the motor over. The start up pressure was 45 psi, I released the built up pressure and it was then brought down to 30 to 32 psi. I'm not sure if the was some kind of "priming" thing that doesn't engage until you turn the motor. Other vehicles that I know of show pressure with the key in the "on" position