3.4 v6 5vze fe running rough

I have a 2000 Tacoma with the 3.4 v6. It has about 195,000 miles on it. Last couple months have been a struggle becuase its been running rough in the low rps but once over 3,000 rpm it smooths out and runs great. My average gas mileage has been between 17-19 witch sounds about right compared to other people. At first my engine light came on and i got it read and it was o2 seniors. So i replaced both of those. Then a couple weeks ago i replaced the mass air flow sensor. At first i thought that was the fix but it wasnt. Its still doing it same thing. Any one recommended anything? I was thinking i should replace my fuel filter and maybe run some seafoam through and see if it clears out.

 

sounds more like fuel related. could be fuel filter. any weird noises?

 

Given that the ignition system is in good shape, it all starts with the fuel pump... if the pump cant build up enough pressure or flow there wont be enough fuel injected. The pump could be questionable, the fuel filter or the pressure regulator. It is going to have to be diagnosed... you might get lucky putting a fuel filter on it as this is pretty easy and relativly inexpensive. The pressure regulator can be checked kind of easy. It is on the D/S fuel rail in the back. Take the vacuum line off and see if there is gas in the line/vacuum port. If there is, the diaphram is shot and the regulator needs to be replaced.

 

Alright thanks for the info i might check and see about that vacuum line you were talking about. Who knows when the fuel filter was changed so i think ill go for that next

 

If it's been a while for a tune up might wanna go that route anyway.

plugs, wires, clean throttle body, IAC, etc...

Also, I suggest getting your own code reader, you can get them for like $20. I have one that's blue tooth and connects to my phone running Torque Pro. That'll tell you the codes. I prefer to see the codes myself rather than have the dude at Auto Zone tell me what he thinks it is.

I would think that if the fuel pump is malfunctioning it would have a harder time in the higher rpms, not the lower... But maybe it's just more noticeable at lower rpms...

 

Ive done plugs, wires, and air filter not too long ago also thinking that would solve the problem

 

So at this time your MIL is off meaning no codes need checked out .

Just what do you mean it runs rough ?? That can mean so many different things to people.

When you changed your spark plugs what did they look like??

It does not seem to be a miss no PO300 codes Idles like it should ??

How does it drive if you keep it under 3000 rpm for 10 or 15 miles does it clear up ??

No hot starting problems ?

 

A little update engine light came up and started to run fine with no issues. I havnt gotten it read yet but I thought that was awfully bizarre. And what I mean running rough is between 2 and 3 thousand rpm its really doggy but clears right up after 3 grand

 

A lot of times its still worth connecting a scanner and running for codes even with no check engine light. Reason is stored codes will not always set a light but will help in diag.

 

Now it barley wants to idle good thing my boss has a code reader

 

Whens the last time u checked your engine air filter? Mine kept trying to stall out at low rpms....had filter covered in mud