4.7 V8 2005 melted intake Manifold Port (1 Viewer)

[TX2UZFE]

fellow 4runner lovers,

I'm scratching my head on this.
Recently acquired an 05 4.7 V8, 2uz-fe, I believe this has the VVTI. Rough Idle, with Misfiring codes (All 8 Cylinders)
spend a couple weeks, on and off to troubleshoot.
I have previously sprayed Carb cleaner before at cold start during idle, no major change in RPM
until I finally sprayed under the intake manifold inside the "Tunnel", was when I finally heard changes in RPM and thought I finally found the problem

spend another morning taking the intake manifold out, thinking either previous owner/ his mechanic did not install the gasket correctly or something in that nature

here is what I found, and I am scratching my head:
one of the intake manifold runner ports, near the injector is melted. or at least part of it is melted.
the same cylinder on the valve port shows no signs of carbon build up, while all the other cylinder ports show what I believe is average carbon build up.

I am about to take the oil pan off to inspect and see if I have any debris, I figure I will post here and see if some one can shed some lights
Thank you in advance!

Questions:
What could cause:
1) intake manifold, near the injector part, to melt?
2) same cylinder, valve port to show almost no sign of carbon build up, unlike the other cylinders?

 

[Commander AJ]

My only idea is that the injector was shorted and creating enough heat to melt the intake, of course that explains why there was no carbon build up as well. If the injector was not firing gas into the port there would be no carbon correct? Can you test the injector?

 

[TX2UZFE]

My only idea is that the injector was shorted and creating enough heat to melt the intake, of course that explains why there was no carbon build up as well. If the injector was not firing gas into the port there would be no carbon correct? Can you test the injector?

Thanks for the reply,

I think the power goes to the Injector are low, and not high enough to generate plastic melting heat. I could be wrong.

I took out the all injectors about 10 days ago, this was before I took out the manifold, and before I saw the melted part.
The injectors seems to be the original factory ones based on my observation.
I tested the injectors with a 9v battery.I cleaned them by blowing the injectors with carb cleaner while tabbing the 9v battery, they all seemed to response normally.

I did notice that the intake manifold gasket are blue in color, so definitely was changed during the previous ownership. and they seemed to be put back together poorly.

I'm browsing on eBay for a new-used manifold, was hoping this forum could offer some ideas, or opinions before I get threw parts to it and melt another manifold

thanks again man

 

[TX2UZFE]

other possibilities that I can think off

clogged exhaust, backed fire?
Blocked EGR?
could it be melted while the manifold was taken off? poor workman ship with poor environment , e.g cigarrette ashes while manifold was on the floor during serviced?

still trying to wrap my ahead around the lack of carbon build up

 

[little_joe]

I am very much a novice to fuel injection systems, and since you posted this I've been trying to understand how this could happen. Logic kind of leads me to believe that maybe either the injector was faulty and/or leaking, or that screen was not installed properly; or was clogged? I say this because of the port: it appears it was either getting way too much fuel, or no fuel?

You tested injector operation, did you check spray pattern before cleaning them?

Out of curiosity, I'd be interested in what the mpg readings are on the in-vehicle display.

 

[ferg]

How is the intake valve?

 

[TX2UZFE]

thanks for the reply
I was out traveling for the long weekend
just got back into project 4runner
i'm taking the valve cover apart.
I did notice the subject port's 2 intake valve seen to be "dropped"
they are just sitting there, I observed suspect valve stems wear marks they seem off

I will report back
thanks again

 

[TX2UZFE]

so I got back to the project, got bitten alive today by mosquitoes (Freaking Texas September weather and rain)
Observation: subject problems port has a valve stuck open, won't move and I rotate the engine.
does it look like it is bent?

 

[ferg]

Compared to the other valve stem in the pic, yes. Run a compression check yet? Can you use a long piece of solid wire and prod the hole/valve to check if it is indeed stuck open?

 

[TX2UZFE]

Compared to the other valve stem in the pic, yes. Run a compression check yet? Can you use a long piece of solid wire and prod the hole/valve to check if it is indeed stuck open?

so I double checked again by rotating the engine and while feeding mosquitoes, one of the valves is indeed stuck open
stuck a long thin screw driver also to verified, while the same runner neighboring valve was closed shut.

next questions:
1) do I remove the engine so I can take the head off?
2) should I rebuild both banks while I am at it
3) can I rebuild head and valve train while the engine is still in engine bay?
4) cheaper/ more efficient to swap engine?

my assumption: whoever was doing timing belt, jumped the timing while putting it together
or timing belt failed while engine was running

 

[ferg]

Not familiar with the 4.7 toy eng. Maybe some more knowledgeable folks will chime in.

 

[turkeythug]

so did you find the cause I bought an 06 that has the same issue it broke 2 intake valves and rod on number 6 cylinder bought to buy used engine and don’t want it to happen again

 

[turkeythug]

Could it possibly be the wrong oil the engine is vvti and it uses oil pressure to adjust the cam timing if so why just number 6

 

[TX2UZFE]

Could it possibly be the wrong oil the engine is vvti and it uses oil pressure to adjust the cam timing if so why just number 6

Didn’t find the cause. I bought the runner knowing it had problems with very rough idling and misfires at all cylinder
I assume the timing was jumped and or the timing belt Broke off at some point.

 

[turkeythug]

I was a Toyota tech for 20 years and only seen it happen once on a sequoia the intake had been hot but at the time it was running fine bought this 06 tundra that wasn’t running much like you knowing it had an issue then found holes in the melted in the intake 2 broken valves and a broken rod on #6 talked to some of the tech I used to work with only one had seen this he said it was the injector on that cylinder that cause it it got dirty but was still letting enough fuel threw to run but was heating up the intake valves

 

[TX2UZFE]

I can definitely see how a leaky injector be the culprit.
my Cylinder #4 bent valve solution was = head taken out and brought to machine shop to have bent valve replaced.
bought an used intake manifold (mine also has a hole on intake port #4), the 4runner is sort of running now
after 5 months of owning it, and working on it on off during non-busy weekends.

This is the first Toyota I owned, I have quite a few friends that have Toyota, they all swear that Toyata is reliable and they are easy to work on.

My own conclusion and opinion is the opposite.
2UZ-FE VVTi = pain in the neck to work on.
Water Pump, thermostat, cooling related gaskets and O-Rings are all pain in the neck to get to.
Even the freaking Fan (you just can't get to the 4 12mm fan bolts easily)

I have been a BMW guy, I think same era Bimmers are much easy to wrench on, but not the newer ones with complex modules and computers

I got the 4runner sort of running now, it is throwing Secondary Air system related code.
Secondary air system is another system that is pain in the neck to work on.

I have dissembled and reassembled the intake manifold so many times that
I can now remove the intake manifold in about 10 mins.
I also ran out of curse words working on this project and am still not done with it

 

[turkeythug]

Yessir the are the v8 is tight in that runner there is a delete kit for the air pump it around 209 bucks it’s my understanding that it works great it kills the limo mode in the ecu as well after I put the next engine in this tundra it will be the next ting I add

 

[turkeythug]

It plugs in at the MAF sensor and a wire to the starter relay and some exhaust port plates it tells the ECU the pumps are working supposed to fix the pump problem they all have

 

[Randy88FJ62]

Interesting to hear the issues you have all reported with the stuck valves. I'm cresting 500,000 on my 4.7 2008 VVTi next week with nothing other than timing belts and basic maintenance.

I wonder what type of abuse from previous owners caused the motors to suffer like this.

 

[TX2UZFE]

Interesting to hear the issues you have all reported with the stuck valves. I'm cresting 500,000 on my 4.7 2008 VVTi next week with nothing other than timing belts and basic maintenance.

I wonder what type of abuse from previous owners caused the motors to suffer like this.

I think low quality fuel and old fuel could ba a cause to clog up injector.
leaky injector could cause misfire and leaked fuel keeps burning
Then the port gets too hot....etc
just a thought, not exactly sure what had happened