Intake duct hose
02-07-11, 01:44 AM
#1
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Intake duct hose
i have a NA s5 streetport
Hello, i recently took my car to a shop to get it diagnosed for some issues i was having, a misfire and it was running lean. He mentioned a small vacuum leak at the acv, i am abou to fix it once i get my money in less than a week, however these problems have occurred before i put a new gasket on the acv which leaks as of now.
The the reason for my thread is something different however, the mechanic mentioned that one of the hoses that plug into the intake duct has too much air passing through it. I know there are two hoses, one that leads to the bac valve and the other goes into the rats nest.
The hose he mentioned was the one going to the rats nest, he said that when he squeezed it, it killed my engine, and according to him that should not happen. He also mentinoed that when he unplugged my blue solenoid, it also killed the engine.
my questions are:
should my engine actually die when the hose is squeezed or the solenoid unplugged?
Also, what could be the cause for the excess air going through the hose? he said i possibly could have a vacuum hose routed wrong is that true?
What would cause my car to die when the blue solenoid is unplugged?
Hello, i recently took my car to a shop to get it diagnosed for some issues i was having, a misfire and it was running lean. He mentioned a small vacuum leak at the acv, i am abou to fix it once i get my money in less than a week, however these problems have occurred before i put a new gasket on the acv which leaks as of now.
The the reason for my thread is something different however, the mechanic mentioned that one of the hoses that plug into the intake duct has too much air passing through it. I know there are two hoses, one that leads to the bac valve and the other goes into the rats nest.
The hose he mentioned was the one going to the rats nest, he said that when he squeezed it, it killed my engine, and according to him that should not happen. He also mentinoed that when he unplugged my blue solenoid, it also killed the engine.
my questions are:
should my engine actually die when the hose is squeezed or the solenoid unplugged?
Also, what could be the cause for the excess air going through the hose? he said i possibly could have a vacuum hose routed wrong is that true?
What would cause my car to die when the blue solenoid is unplugged?
02-07-11, 02:28 PM
#2
Does this "mechanic" just go around squeezing and unplugging things until the car stalls? Has he never heard of a manual?
Assuming the guy did not squeeze the BAC hose while the engine was running (that could in fact stall it), the other hose coming off the intake duct would either be for the injector air bleeds or the oil injectors. Both of these use metered air (not vacuum). Off the top of my head, I'm not sure which one it is, but I'd lean towards it being for the oil injectors. An S5 NA owner may know for sure, since it's not shown in the FSM vac diagram: https://www.rx7club.com/showthread.p...vacuum+diagram.
For either of these systems, there should be no reason that cutting off the air supply would noticeably affect how the engine runs.
Same goes for the blue relief solenoid. This just operates the relief valve in the ACV, which directs air pump air to the exhaust/main cat or out the relief port. It's not involved with how the engine idles, so there shouldn't be a reason that unplugging it would cause the engine to stall. Disconnecting its vacuum lines on the other hand will create a vac leak that could make idle rough enough to stall.
What were the symptoms of your original problem(s)? You mentioned a misfire and running lean. How do you know it was running lean, and when would it occur? A vacuum leak can cause a lean condition (typically at idle) that can stall an engine.
Assuming the guy did not squeeze the BAC hose while the engine was running (that could in fact stall it), the other hose coming off the intake duct would either be for the injector air bleeds or the oil injectors. Both of these use metered air (not vacuum). Off the top of my head, I'm not sure which one it is, but I'd lean towards it being for the oil injectors. An S5 NA owner may know for sure, since it's not shown in the FSM vac diagram: https://www.rx7club.com/showthread.p...vacuum+diagram.
For either of these systems, there should be no reason that cutting off the air supply would noticeably affect how the engine runs.
Same goes for the blue relief solenoid. This just operates the relief valve in the ACV, which directs air pump air to the exhaust/main cat or out the relief port. It's not involved with how the engine idles, so there shouldn't be a reason that unplugging it would cause the engine to stall. Disconnecting its vacuum lines on the other hand will create a vac leak that could make idle rough enough to stall.
What were the symptoms of your original problem(s)? You mentioned a misfire and running lean. How do you know it was running lean, and when would it occur? A vacuum leak can cause a lean condition (typically at idle) that can stall an engine.
02-11-11, 07:22 PM
#6
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ok well i had time to mess with my car and all that today
I tried squeezing the hose the mechanic was talking about and it didn't do anything -.-
however when i unplug the blue relief solenoid my car really does die, and i'm not sure why.
i figure that there is either some kind of wiring problem (or misrouted vacuum line), or something wrong with the acv
I heard somewhere that there is such thing as an internal vaccum leak inside the acv if it is worn out. I was looking at the pic of the ACV in the fsm f1-61 (fuel and emissions) and i noticed that the air from the air pump, after going through the relief valve can pass through the air control valve directly into the intake. i was curious if for some reason this would cause more air then i need to go into the intake if something is wrong with the ACV, but im not sure how this would cause my engine to die with the blue solenoid taken off...
I was also wondering if the loss of vacuum because of the street port would cause any of these problems...
I tried squeezing the hose the mechanic was talking about and it didn't do anything -.-
however when i unplug the blue relief solenoid my car really does die, and i'm not sure why.
i figure that there is either some kind of wiring problem (or misrouted vacuum line), or something wrong with the acv
I heard somewhere that there is such thing as an internal vaccum leak inside the acv if it is worn out. I was looking at the pic of the ACV in the fsm f1-61 (fuel and emissions) and i noticed that the air from the air pump, after going through the relief valve can pass through the air control valve directly into the intake. i was curious if for some reason this would cause more air then i need to go into the intake if something is wrong with the ACV, but im not sure how this would cause my engine to die with the blue solenoid taken off...
I was also wondering if the loss of vacuum because of the street port would cause any of these problems...
02-11-11, 07:31 PM
#7
ok well i had time to mess with my car and all that today
I tried squeezing the hose the mechanic was talking about and it didn't do anything -.-
however when i unplug the blue relief solenoid my car really does die, and i'm not sure why.
i figure that there is either some kind of wiring problem (or misrouted vacuum line), or something wrong with the acv
I heard somewhere that there is such thing as an internal vaccum leak inside the acv if it is worn out. I was looking at the pic of the ACV in the fsm f1-61 (fuel and emissions) and i noticed that the air from the air pump, after going through the relief valve can pass through the air control valve directly into the intake. i was curious if for some reason this would cause more air then i need to go into the intake if something is wrong with the ACV, but im not sure how this would cause my engine to die with the blue solenoid taken off...
I was also wondering if the loss of vacuum because of the street port would cause any of these problems...
I tried squeezing the hose the mechanic was talking about and it didn't do anything -.-
however when i unplug the blue relief solenoid my car really does die, and i'm not sure why.
i figure that there is either some kind of wiring problem (or misrouted vacuum line), or something wrong with the acv
I heard somewhere that there is such thing as an internal vaccum leak inside the acv if it is worn out. I was looking at the pic of the ACV in the fsm f1-61 (fuel and emissions) and i noticed that the air from the air pump, after going through the relief valve can pass through the air control valve directly into the intake. i was curious if for some reason this would cause more air then i need to go into the intake if something is wrong with the ACV, but im not sure how this would cause my engine to die with the blue solenoid taken off...
I was also wondering if the loss of vacuum because of the street port would cause any of these problems...
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02-11-11, 10:38 PM
#8
Rotary Freak
The airpump air will go from the airpump to the ACV. IF the car is at idle, the air will go thu a spoked checkvalve into the exhaust manifold. NOT the intake manifold.
The Relief solenoid keeps vacuum on the ACV's relief solenoid to prevent the airpump air from going into the silencer in the right front fender via the LARGE nipple on the outbd side of the ACV (has a large black hose on it).
There is a ANTI AFTERBURN valve internal to the ACV and that is the only path for airpump air to get into the intake manifold. This only happens when you driving the car and let off the gas pedal. The vacuum in the intake manifold sucks on the bottom of that diaphram called the AAV in the picture which creates a path for the airpump air .......past the AAV poppet valve....and then onto the rear intake port. A very small pinhole size hole in that intake port. AAV prevents backfire on deceleration.
You know something? The Relief and Switching solenoids supply vacuum to the ACV. Now on a series FOUR that is done by two small vacuum nipples located NOT on the ACV itself, but just above the ACV on the manifold. So the path would have to go thru those nipple........thru the path in the manifold to the mating surface of the ACV and on to the guts of the ACV to their respective diaphrams.
What all the above means to me is................it could be the gasket b/t the ACV and manifold is leaking where those two paths of vacuum are...........causing your problem. So you buy a can of starter fluid. Idle the car fully warmed up and spray around the top side of the ACV and listen for a change of rpm as you do that. IF the gasket is leaking........the rpms will??? rise or fall. Depends.
The Relief solenoid keeps vacuum on the ACV's relief solenoid to prevent the airpump air from going into the silencer in the right front fender via the LARGE nipple on the outbd side of the ACV (has a large black hose on it).
There is a ANTI AFTERBURN valve internal to the ACV and that is the only path for airpump air to get into the intake manifold. This only happens when you driving the car and let off the gas pedal. The vacuum in the intake manifold sucks on the bottom of that diaphram called the AAV in the picture which creates a path for the airpump air .......past the AAV poppet valve....and then onto the rear intake port. A very small pinhole size hole in that intake port. AAV prevents backfire on deceleration.
You know something? The Relief and Switching solenoids supply vacuum to the ACV. Now on a series FOUR that is done by two small vacuum nipples located NOT on the ACV itself, but just above the ACV on the manifold. So the path would have to go thru those nipple........thru the path in the manifold to the mating surface of the ACV and on to the guts of the ACV to their respective diaphrams.
What all the above means to me is................it could be the gasket b/t the ACV and manifold is leaking where those two paths of vacuum are...........causing your problem. So you buy a can of starter fluid. Idle the car fully warmed up and spray around the top side of the ACV and listen for a change of rpm as you do that. IF the gasket is leaking........the rpms will??? rise or fall. Depends.
02-11-11, 10:43 PM
#9
Rotary Freak
Or try what Satch is going to get to pretty soon..........idle the car. Above the ACV should be two small nipples with vac hose on them. Pull one off at a time and see if the hose has vacuum on it. Should. Both should.
Or.....when you pull them off one at a time and rapidly put your finger over the hose's opening........which hose when pulled off causes the engine to die?
Or.....when you pull them off one at a time and rapidly put your finger over the hose's opening........which hose when pulled off causes the engine to die?
02-14-11, 05:15 PM
#11
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The airpump air will go from the airpump to the ACV. IF the car is at idle, the air will go thu a spoked checkvalve into the exhaust manifold. NOT the intake manifold.
The Relief solenoid keeps vacuum on the ACV's relief solenoid to prevent the airpump air from going into the silencer in the right front fender via the LARGE nipple on the outbd side of the ACV (has a large black hose on it).
There is a ANTI AFTERBURN valve internal to the ACV and that is the only path for airpump air to get into the intake manifold. This only happens when you driving the car and let off the gas pedal. The vacuum in the intake manifold sucks on the bottom of that diaphram called the AAV in the picture which creates a path for the airpump air .......past the AAV poppet valve....and then onto the rear intake port. A very small pinhole size hole in that intake port. AAV prevents backfire on deceleration.
You know something? The Relief and Switching solenoids supply vacuum to the ACV. Now on a series FOUR that is done by two small vacuum nipples located NOT on the ACV itself, but just above the ACV on the manifold. So the path would have to go thru those nipple........thru the path in the manifold to the mating surface of the ACV and on to the guts of the ACV to their respective diaphrams.
What all the above means to me is................it could be the gasket b/t the ACV and manifold is leaking where those two paths of vacuum are...........causing your problem. So you buy a can of starter fluid. Idle the car fully warmed up and spray around the top side of the ACV and listen for a change of rpm as you do that. IF the gasket is leaking........the rpms will??? rise or fall. Depends.
The Relief solenoid keeps vacuum on the ACV's relief solenoid to prevent the airpump air from going into the silencer in the right front fender via the LARGE nipple on the outbd side of the ACV (has a large black hose on it).
There is a ANTI AFTERBURN valve internal to the ACV and that is the only path for airpump air to get into the intake manifold. This only happens when you driving the car and let off the gas pedal. The vacuum in the intake manifold sucks on the bottom of that diaphram called the AAV in the picture which creates a path for the airpump air .......past the AAV poppet valve....and then onto the rear intake port. A very small pinhole size hole in that intake port. AAV prevents backfire on deceleration.
You know something? The Relief and Switching solenoids supply vacuum to the ACV. Now on a series FOUR that is done by two small vacuum nipples located NOT on the ACV itself, but just above the ACV on the manifold. So the path would have to go thru those nipple........thru the path in the manifold to the mating surface of the ACV and on to the guts of the ACV to their respective diaphrams.
What all the above means to me is................it could be the gasket b/t the ACV and manifold is leaking where those two paths of vacuum are...........causing your problem. So you buy a can of starter fluid. Idle the car fully warmed up and spray around the top side of the ACV and listen for a change of rpm as you do that. IF the gasket is leaking........the rpms will??? rise or fall. Depends.
i don't know that ive ever tried it, but unplugging the blue solenoid shouldn't make it stall. like hailers says it'll just re route air pump air.
if it was MY car i would pull the ACV, and check it, reseal it and then check the ROUTING of the vacuum lines, the s5 is pretty good, but i still have to verify that the hose from the solenoid goes to the proper valve.
02-14-11, 06:03 PM
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Ok so i went and pulled the vacuum lines above the acv, when i pulled the one on the right the AFR got really rich and the engine wanted to die. What does this mean? The other one didn't kill the engine
02-14-11, 06:04 PM
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It is a source for problems IMO. Removing it simplifies the engine in a big way. The only way i can see it being trouble free is actually taking it out and replacing all the vacuum lines with high quality lines and zip ties.
02-14-11, 07:44 PM
#15
Pulling the vacuum hose on the right will cause the air pump air to be vented to the atmosphere which then removes air destined to be mixed with the exhaust gases and thus makes the exhaust gases present to have a higher fuel to air mixture and thus a richer AFR. You stated the engine "wanted" to die but did not actually cut out. Depending on your idle rpm before the hose is pulled will basically dictate whether the engine will sound like it wants to conk out or not. Sounds like if the engine were idling a bit higher then when the hose was pulled it would sound a bit stronger.
02-14-11, 08:09 PM
#16
Rotary Freak
Pulling the BLUE plug off should make the airpump air discharge out the very LARGE nipple on the outboard side of the ACV. This test more or less proves the vac lines from the Relief solenoid to the ACV are routed right.
The afr should get much richer. Much much richer. Why? Cause the airpump air normally goes to the exhaust ports AT the engine/exhaust header interface. You probably notice in the past that the 02 sensor is downstream of the exhaust ports. Therefore if you add air to the exhaust gases the afr gets leaner (as read by the 02 sensor...the afr of the fuel mixture does not change at all). And if you remove that air from the ACV being mixed with the exhaust gases...........the 02 sensor reads richer. Remember........the actual afr of the fuel in the engine does not change at all. That's why if your using a afr gauge you should remove the airpump or at least remove the Blue connector off the Relief solenoid so the airpump air will dump overboared and NOT go into the exhaust ports. Get it????????
Anyway, when you did remove the blue connector or removed the vac line just above the ACV.........the engine should not have changed tone much at all. It might change just a bit because the air going to the exhaust ports is also sucked up into the intake stroke to some extent.
But the engine going all wobbly cause the blue plug or vac line was removed.......Something is odd about that. Did you ever spray the starter fluid around the exterior of the ACV while it's running? Is the spoked check valve installed b/t the ACV and the intake mating surface???? Check and make sure it's there.
By the way...........I was getting ready for emissions inspection yesterday on one of my turbo cars. I noticed that when the airpump was on the car and ACV on the car and all vac lines connected where they belong...............my AFR was rich. Wayyy rich. I'm talking at idle. Well buggers. I swapped in a spare ACV and had the same problem.
So I thunk about it and then remove the ACV and pulled the spoked checkvalve. Eeek? From lack of use the thing was corroded up on the inbd side of the valve so bad that the small rubber flap was frozen solid with crud. Meaning that the airpump air couldn't get to the path to the exhaust ports.......in turn meaning the 02 would read an abnormal Rich condition at idle. At idle a NORMAL RX will read reeaeeeel lean.......'cause the air is mixed with the exhaust gasses making it read lean at the 02 sensor which is a couple feet downstream.
Got a spare checkvalve that was not corroded up and installed it. Now the car reads exteremly lean at idle..........like a normal non messed with stk RX will read.
You might remove the ACV and black RTV the two holes that relate to the anti afterburn valve internal to the ACV. That would eliminated the anti afterburn valve being the culprit.
Or you gasket might just be trash and letting airpump air go where it should not go.........like into one of the three passages in the ACV cavity that lead to the inlet runners. Make a new gasket and install it and see what happens.
Non turbo car. Acturally I forget which of the two small vac lines above the ACV is Relief related and which is Switching related. I figure you got it right though.
The afr should get much richer. Much much richer. Why? Cause the airpump air normally goes to the exhaust ports AT the engine/exhaust header interface. You probably notice in the past that the 02 sensor is downstream of the exhaust ports. Therefore if you add air to the exhaust gases the afr gets leaner (as read by the 02 sensor...the afr of the fuel mixture does not change at all). And if you remove that air from the ACV being mixed with the exhaust gases...........the 02 sensor reads richer. Remember........the actual afr of the fuel in the engine does not change at all. That's why if your using a afr gauge you should remove the airpump or at least remove the Blue connector off the Relief solenoid so the airpump air will dump overboared and NOT go into the exhaust ports. Get it????????
Anyway, when you did remove the blue connector or removed the vac line just above the ACV.........the engine should not have changed tone much at all. It might change just a bit because the air going to the exhaust ports is also sucked up into the intake stroke to some extent.
But the engine going all wobbly cause the blue plug or vac line was removed.......Something is odd about that. Did you ever spray the starter fluid around the exterior of the ACV while it's running? Is the spoked check valve installed b/t the ACV and the intake mating surface???? Check and make sure it's there.
By the way...........I was getting ready for emissions inspection yesterday on one of my turbo cars. I noticed that when the airpump was on the car and ACV on the car and all vac lines connected where they belong...............my AFR was rich. Wayyy rich. I'm talking at idle. Well buggers. I swapped in a spare ACV and had the same problem.
So I thunk about it and then remove the ACV and pulled the spoked checkvalve. Eeek? From lack of use the thing was corroded up on the inbd side of the valve so bad that the small rubber flap was frozen solid with crud. Meaning that the airpump air couldn't get to the path to the exhaust ports.......in turn meaning the 02 would read an abnormal Rich condition at idle. At idle a NORMAL RX will read reeaeeeel lean.......'cause the air is mixed with the exhaust gasses making it read lean at the 02 sensor which is a couple feet downstream.
Got a spare checkvalve that was not corroded up and installed it. Now the car reads exteremly lean at idle..........like a normal non messed with stk RX will read.
You might remove the ACV and black RTV the two holes that relate to the anti afterburn valve internal to the ACV. That would eliminated the anti afterburn valve being the culprit.
Or you gasket might just be trash and letting airpump air go where it should not go.........like into one of the three passages in the ACV cavity that lead to the inlet runners. Make a new gasket and install it and see what happens.
Non turbo car. Acturally I forget which of the two small vac lines above the ACV is Relief related and which is Switching related. I figure you got it right though.
03-11-11, 02:04 AM
#18
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Ok i put on the acv gasket and my afr is about right the idle is in the 13s and the idle is not nearly as rough however i still have a small misfire from something...
03-11-11, 01:12 PM
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i should go plug in my WB and see what the car does at idle with the blue solenoid unplugged, mine is an s4, id guess mid 12's, s5 might be a little leaner
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