Rough Idle, poor acceleration (Video included)

[Josho]

https://youtu.be/JiA5v9u97OQ

Idle and rev video.

I'm having a hard time diagnosing this issue.
Things I have done:
Replaced MAF
Replaced TPS
Cleaned IACV
Removed catalytic converter
Replaced spark plugs and wires
Cleaned throttle body
Checked for Vac leaks
Checked cylinder compression (Came back good, all between 210-195)
Checked fuel pressure (42 psi)
Replaced fuel filter

I'm getting no trouble codes. The engine boggs if I rev it too hard and it also makes a jiggling noise when it's rev'd beyond 2k rpms.

 

[thegipper]

Bad gas?
Spark plugs/wires
coil
fuel injector
Vacuum leak

hard to say

 

[mckennar]

https://youtu.be/JiA5v9u97OQ

Idle and rev video.

I'm having a hard time diagnosing this issue.
Things I have done:
Replaced MAF
Replaced TPS
Cleaned IACV
Removed catalytic converter
Replaced spark plugs and wires
Cleaned throttle body
Checked for Vac leaks
Checked cylinder compression (Came back good, all between 210-195)
Checked fuel pressure (42 psi)
Replaced fuel filter

I'm getting no trouble codes. The engine boggs if I rev it too hard and it also makes a jiggling noise when it's rev'd beyond 2k rpms.

What kind of manifold vacuum are you seeing at warm idle? How about under load?

Hows your timing?

Do you have a way of telling whether you're running rich / lean?

Sounds kind of like a vac leak, almost like an intake manifold gasket whistle (in the video) but I've never actually seen one on a 5vz-fe (and I know you mentioned you checked). How did you check (smoke test?).

Either way, good luck!

 

[Buckaroo]

You have done a lot of good work chasing this problem. As others have said, bad gas worthy of thought and checking engine vacuum is also good. Vacuum gauge is inexpensive and useful. I've attached some generic info on that. Also, good question on how you checked for vacuum leak....smoke machine great tool but very expensive. You can check by spraying brake clean on vacuum lines and around intake manifold gasket - if the engine noise changes (typically it will stumble), you have found the leak.....but, it's very flammable so take care.

Buckaroo

 

[calebcalandra]

Maybe time for new spark plugs?

 

[Josho]

You have done a lot of good work chasing this problem. As others have said, bad gas worthy of thought and checking engine vacuum is also good. Vacuum gauge is inexpensive and useful. I've attached some generic info on that. Also, good question on how you checked for vacuum leak....smoke machine great tool but very expensive. You can check by spraying brake clean on vacuum lines and around intake manifold gasket - if the engine noise changes (typically it will stumble), you have found the leak.....but, it's very flammable so take care.

Buckaroo

I have done the basic procedure for hunting down a vacuum leak, good ol brake clean! Nothing came from it. Although, if the intake manifold is leaking, maybe the spray didn't make it that far. And these have 2 piece intake manifolds? I don't recall at the moment. I will investigate the idea of a vacuum leak some more.
What kills me is that it doesn't throw a trouble code.

 

[Josho]

What kind of manifold vacuum are you seeing at warm idle? How about under load?

Hows your timing?

Do you have a way of telling whether you're running rich / lean?

Sounds kind of like a vac leak, almost like an intake manifold gasket whistle (in the video) but I've never actually seen one on a 5vz-fe (and I know you mentioned you checked). How did you check (smoke test?).

Either way, good luck!

The timing marks line up, although I have not used a timing light on it. And my newly replaced spark plugs have white tips, indicating lean conditions on all 6 cylinders.

 

[OldManKamps]

I have done the basic procedure for hunting down a vacuum leak, good ol brake clean! Nothing came from it. Although, if the intake manifold is leaking, maybe the spray didn't make it that far. And these have 2 piece intake manifolds? I don't recall at the moment. I will investigate the idea of a vacuum leak some more.
What kills me is that it doesn't throw a trouble code.

They are two piece intakes.

 

[mckennar]

And these have 2 piece intake manifolds? I don't recall at the moment. I will investigate the idea of a vacuum leak some more.
What kills me is that it doesn't throw a trouble code.

What idle RPM are you at warm? Because this would sometimes also manifest itself as a higher-than-normal idle.

 

[Josho]

What idle RPM are you at warm? Because this would sometimes also manifest itself as a higher-than-normal idle.

When it's warm, the idle raises and falls quickily. But stays between 700-900. It's not a crazy idle surge like a bad iac valve would cause. It's a quick raise and fall, almost like a small cam upgrade.

 

[Josho]

You have done a lot of good work chasing this problem. As others have said, bad gas worthy of thought and checking engine vacuum is also good. Vacuum gauge is inexpensive and useful. I've attached some generic info on that. Also, good question on how you checked for vacuum leak....smoke machine great tool but very expensive. You can check by spraying brake clean on vacuum lines and around intake manifold gasket - if the engine noise changes (typically it will stumble), you have found the leak.....but, it's very flammable so take care.

Buckaroo

Any further suggestions? All spark plugs have white tips. How likely would it be to have a bad o2 sensor but not have a trouble code?

 

[TXRick]

PCV?

Could you use Seafoam as a poor man's smoke machine?

 

[A.Wilson013]

PCV?

Could you use Seafoam as a poor man's smoke machine?

Here's my poor man's smoke machine.

Of course only my dogs will kiss me for the next week, but that's fine.

 

[TXRick]

Yeah...that probably wouldn't work. I was thinking backwards I love some sweets!

 

[LittleCaesar]

These 4runners love their OEM parts. Sometime not even the maker's (ex Denso) part will work correctly.

Got access to a scanner?

Never seen a 5vz run without its top end cover before.

 

[Metallurgist]

Do all spark plugs have white or just some of them? Have you checked injectors because maybe they're starving the cylinders. Your pressure looks like it's right where it should be. Maybe the injectors need cleaned. Heard about these guys today (I know, they're probably already well-known, but it's not something I commonly have seen). I'm thinking about doing this myself.

https://www.deatschwerks.com/services/fuel-injector-services

 

[Josho]

Do all spark plugs have white or just some of them? Have you checked injectors because maybe they're starving the cylinders. Your pressure looks like it's right where it should be. Maybe the injectors need cleaned. Heard about these guys today (I know, they're probably already well-known, but it's not something I commonly have seen). I'm thinking about doing this myself.

https://www.deatschwerks.com/services/fuel-injector-services

Yes, all spark plug tips are white. I have not tried a smoke test to check for vacuum leaks. If I ran the seafoam through the main vacuum source, wouldn't that show something? Assuming there is a leak.

 

[Metallurgist]

Yes, all spark plug tips are white. I have not tried a smoke test to check for vacuum leaks. If I ran the seafoam through the main vacuum source, wouldn't that show something? Assuming there is a leak.

My smarter car buddy informed me this morning that new plugs will look white because a NA engine naturally runs lean. The only reason they wouldn't is if something was off so that they're putting too much in to make it black. Plugs that have been used for a while will naturally get buildup on them. Since they're all white and they're new, I would guess that your air fuel mixture is right and your problem is somewhere else.

 

[TXRick]

Yes, all spark plug tips are white. I have not tried a smoke test to check for vacuum leaks. If I ran the seafoam through the main vacuum source, wouldn't that show something? Assuming there is a leak.

I've got a vacuum leak somewhere and thought maybe the seafoam thing would work but now that I think about it, I believe the seafoam would got straight to the manifold and then ignite thus lots of smoke out the tailpipe but not in the vacuum system...may be wrong.

 

[Josho]

Here is a video of it running/driving. It's a slight uphill acceleration, but still very sluggish. It also has a funny sounding exhaust note.