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it's like this but mine is a reddish color (faded). it has Ford TVS D7EE-AA stamped on it.
There are several versions of this for differing climates. The part that is mounted onto the air box is the temperature measuring bit that opens/closes as it measures the temperature flowing
thru the air box. I wonder if mine is stuck open and it is passing exhaust gas thru all the time?
I just went out and did some tests on the air valve on the air box intake tube that has the round valve on it that allows the intake gases to be injected into the air stream. It works as it should and holds vacuum.
I took the nipple on the intake vacuum tree side off and put a hose on it and tried to suck thru the valve on the air box. the valve is closed. so it must just not be warm enough for air to be passed thru I take it.
Maybe there is nothing wrong here...and I'm chasing ghosts.
Exhaust leaks is what to look at
or
the system is actually running lean
That valve and the air cleaner door are part of the EFE system (early fuel evaporation)
The air cleaner flapper door is controlled by a TVS (thermal vacuum switch) that is what's in your air cleaner
It will take more than that small vacuum leak to cause the O2 sensor to be "slammed" lean
I'd do an intake manifold leak test with brakleen or carb foam. Flammable brakleen works well for that
I use the non flammable stuff and watch for the motor to slow down the idle speed, not speed up
Have you checked for engine codes?
Are the air injection system, crossover tube, check valves and divert valve at the back of the cylinder heads intact?
How is the connection of the two small gauge wires at your battery negative terminal and your main ground cable to your frame and engine block?
When installed, the O2 sensor is grounded through it's threads, through the exhaust system.
Have you checked for engine codes?
Are the air injection system, crossover tube, check valves and divert valve at the back of the cylinder heads intact?
How is the connection of the two small gauge wires at your battery negative terminal and your main ground cable to your frame and engine block?
When installed, the O2 sensor is grounded through it's threads, through the exhaust system.
Have not checked codes since getting into the O2 sensor testing. bitchin rain/wind storm here overnight which will delay things.
The O2 sensor is working and producing voltage...just in the 101-275 milli-volt range..meaning low always (lean).
The pipes and valves behind the intake are intact as far as I can see. I put a new TAD valve in last year along with the right side check valve.
I could not get the lower one off to replace it but I did verify I could push air down towards the CAT when I had it apart.
The TAB valve is working as it should tested that out already. Should be getting vacuum now to that valve as I put all new lines on 2 days
ago from the vacuum canister from the vac tree and thru to the TAB/TAD/EGR valves solenoids.
Battery ground wire connection were cleaned up good last year and I put my special goop on the connection to keep them from corroding.
Codes, including key on engine running, might point you towards something like the secondary air system or the EGR system.
You could try leaning over the intake on the driver's side, and disconnecting the hose from the divert valve, that runs to the crossover tube, to see if air is constantly being pushed to the heads.
Also if you have exhaust pulses coming out of that hose, the check valve on top of the crossover tube has failed.
Air should only go to the heads after about 90 seconds after a cold start, then divert to the catalytic converter when the engine reaches operating temperature.
The TAB valve works properly - I tested it. To rule out the air from the pump being sent into the TAD valve by removing the vacuum line from the
TAB valve causes the air to be expelled to the atmosphere vent holes on the valve. I did that test and that is what it did. That would rule out
the air system from being the source of the air going to the heads &| the CAT.
The TAB valve works properly - I tested it. To rule out the air from the pump being sent into the TAD valve by removing the vacuum line from the
TAB valve causes the air to be expelled to the atmosphere vent holes on the valve. I did that test and that is what it did. That would rule out
the air system from being the source of the air going to the heads &| the CAT.
Are you saying you left the vacuum line disconnected from the bypass valve, so it is always dumping to the atmosphere? That would keep air pump air from going to the divert valve.
There would still be the possibility of an opening in the crossover tube, the divert valve or the check valve, that would allow air into the back of the heads.
You would be able to feel that as exhaust pulses.
when it warms/dries up here I'll be doing that very test. My brother just dropped off an inspection mirror to check the pipes/valves out.
I had taken the vacuum line off the TAB valve to test to rule out the air from the pump being the source of air being introduced into the mix
causing the lean condition.
OK, getting somewhere....I put the shop vac on blow mode and taped it onto the exhaust (truck off)...and fired the shop vac up.
liberally coated the resonator, pipe moving towards the cat, the cat itself, bung pipe the O2 sensor uses, the Y pipe leading
up to the manifold and low and behold when I sprayed it with the soapy water spray, started bubbling around cylinder #4.
this may be the leak.
note that I tried looking at the rear of the engine bay behind the intake with a mirror but cannot really see anything. to inspect
that area properly would require removing the intake (again)...
should I just bite the bullet here and buy 2 new manifolds and have them put on? or are they salvageable?
Is it the gasket leaking or the manifold itself? If the manifold, I would replace both. Be ready for broken bolts. I would have new ones on hand, all new.
really have no idea...until I start taking things apart will not know for sure. the heat shields are obscuring my view of the area. I believe they are not supposed to have any
gasket if they are original to the truck...but after 40 years of operation, who knows.
will start soaking the bolts with PB blaster over the coming days...before attempting this.
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