ACV Testing
05-31-12, 03:37 PM
#1
Unconventional
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ACV Testing
Ok, reading through the FSM (88 NA) I'm lost on a couple steps.
Page: 4A-42
Step 4 says "Place a finger over the air control valve outlet."
What am I looking for, vacuum/pressure/nothing?
Step 11 says "Place a finger over the port opening."
Again, what am I looking for?
Page: 4A-42
Step 4 says "Place a finger over the air control valve outlet."
What am I looking for, vacuum/pressure/nothing?
Step 11 says "Place a finger over the port opening."
Again, what am I looking for?
05-31-12, 04:12 PM
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After reading it over and over and over, I take it that:
Step 8 should read "Check that air flows out from the relief air port."
and
Step 13 should read "Check that air flows out from the split air port."
The way they have it in there, it looked like air should be flowing OUT of the vacuum lines at the solenoid valves.
So, at idle there should be no air from either port. If I remove the vacuum line to the corresponding solenoid valve, then there should be air. Upon reconnecting the vacuum lines to the solenoid valves, there should once again be no air.
Is that correct?
Step 8 should read "Check that air flows out from the relief air port."
and
Step 13 should read "Check that air flows out from the split air port."
The way they have it in there, it looked like air should be flowing OUT of the vacuum lines at the solenoid valves.
So, at idle there should be no air from either port. If I remove the vacuum line to the corresponding solenoid valve, then there should be air. Upon reconnecting the vacuum lines to the solenoid valves, there should once again be no air.
Is that correct?
Last edited by Jet-Lee; 05-31-12 at 04:14 PM.
05-31-12, 04:23 PM
#5
Why don't you go through the procedure specified in the FSM step by step applying it to the actual testing of your ACV and not worry about something 8 steps ahead until you reach that particular step. There are only two possibilties as either there will be outflow or inflow so compare what you got to what is mentioned in the procedure.
05-31-12, 04:33 PM
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I did go step by step, you dolt. I came here because the wording is weird so I'm asking for clarification.
It says "Check that air flows out."
Flows out from where? The vacuum line that was disconnected in the previous step or the relief air opening that was disconnected 4 steps prior? That's what I'm asking.
Perhaps you need to read it.
It says "Check that air flows out."
Flows out from where? The vacuum line that was disconnected in the previous step or the relief air opening that was disconnected 4 steps prior? That's what I'm asking.
Perhaps you need to read it.
05-31-12, 04:41 PM
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1. Warm up engine to normal operating temperature.
2. Connect a tachometer to the Engine.
3. Disconnect the air hose (air silencer to air control valve) at the air control calce.
4. Place a finger over the air control valve outlet.
5. Increase the engine speed and check that air begins to flow out between 1,500 and 2,500 rpm.
6. Run engine at idle speed.
7. Disconnect the vacuum hose (relief solenoid valve to air control valve) at the relief solenoid valve.
8. Check that air flows out. From where?
9. Reconnect the vacuum hose and the air hose.
10. Disconnect the split air hose (check valve to intake manifold) at the intake manifold.
11. Place a finger of the port opening.
12. Disconnect the vacuum hose (switching solenoid valve to air control valve) at the switching solenoid valve.
13. Check that air flows out. From where?
14. Reconnect the vacuum hose and split air hose.
15. Replace the air control valve, if necessary.
2. Connect a tachometer to the Engine.
3. Disconnect the air hose (air silencer to air control valve) at the air control calce.
4. Place a finger over the air control valve outlet.
5. Increase the engine speed and check that air begins to flow out between 1,500 and 2,500 rpm.
6. Run engine at idle speed.
7. Disconnect the vacuum hose (relief solenoid valve to air control valve) at the relief solenoid valve.
8. Check that air flows out. From where?
9. Reconnect the vacuum hose and the air hose.
10. Disconnect the split air hose (check valve to intake manifold) at the intake manifold.
11. Place a finger of the port opening.
12. Disconnect the vacuum hose (switching solenoid valve to air control valve) at the switching solenoid valve.
13. Check that air flows out. From where?
14. Reconnect the vacuum hose and split air hose.
15. Replace the air control valve, if necessary.
This is what I gather to be correct, can anyone confirm?
Originally Posted by Jet-Lee
So, at idle there should be no air from either port. If I remove the vacuum line to the corresponding solenoid valve, then there should be air. Upon reconnecting the vacuum lines to the solenoid valves, there should once again be no air.
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05-31-12, 04:51 PM
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#8 the air flows out of the ACV outlet you put your finger over in step 4.
#13 the air flows out of the split air passage in the intake manifold that you put your finger over in step 11. there is a hose there, and they want you to disconnect the bottom side, so the top side is still connected to the intake manifold.
there are two valves in the ACV to control the air pump air. the relief, step 8, switches between dumping the air pump air into the silencer and sending the air pump air to the switching valve. so when you pull the vacuum line off the acv, the acv will relive the air pump air to atmosphere. the switching valve #13, switches between "Port air" and Split air". split air is the pipe that goes to the main cat. Port air is literally the exhaust ports.
its a simple device, don't let the FSM fool you
#13 the air flows out of the split air passage in the intake manifold that you put your finger over in step 11. there is a hose there, and they want you to disconnect the bottom side, so the top side is still connected to the intake manifold.
there are two valves in the ACV to control the air pump air. the relief, step 8, switches between dumping the air pump air into the silencer and sending the air pump air to the switching valve. so when you pull the vacuum line off the acv, the acv will relive the air pump air to atmosphere. the switching valve #13, switches between "Port air" and Split air". split air is the pipe that goes to the main cat. Port air is literally the exhaust ports.
its a simple device, don't let the FSM fool you
05-31-12, 04:56 PM
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#8 the air flows out of the ACV outlet you put your finger over in step 4
#13 the air flows out of the split air passage in the intake manifold that you put your finger over in step 11. there is a hose there, and they want you to disconnect the bottom side, so the top side is still connected to the intake manifold.
#13 the air flows out of the split air passage in the intake manifold that you put your finger over in step 11. there is a hose there, and they want you to disconnect the bottom side, so the top side is still connected to the intake manifold.
So no air is supposed to come out of either, at idle, with the vacuum lines connected to the solenoid valves, correct?
I have a little coming out of the ACV outlet in #4.
I was trying to go about continuing down the list when I ran into this verbage issue, then satch not being of any assistance.
05-31-12, 05:01 PM
#12
And I did help you on your initial post.
05-31-12, 05:02 PM
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Thank you!
So no air is supposed to come out of either, at idle, with the vacuum lines connected to the solenoid valves, correct?
I have a little coming out of the ACV outlet in #4. I was trying to go about continuing down the list when I ran into this verbage issue, then satch not being of any assistance.
So no air is supposed to come out of either, at idle, with the vacuum lines connected to the solenoid valves, correct?
I have a little coming out of the ACV outlet in #4.
I was trying to go about continuing down the list when I ran into this verbage issue, then satch not being of any assistance.it is confusing because there is a page where you test the solenoids too, so you'd be checking to see if they had vacuum at the appropriate times.
05-31-12, 05:21 PM
#14
Rotary Freak
Step number eight: air will flow from the large port on the ACV that had a hose on it that goes to the silencer in the right fender.
Step number 13: from the port that the split air hose was attached to. You will feel very little air when doing this FYI. Almost just a wisp of air. This step is not as essential as the step eight where there should be a very noticable increase in the air coming out the ACV relief port (where the large hose going to the silencer attaches.
ACV solenoids do very much nothing. The ACV is controlled by the Relief (blue) and Switching (grey) solenoids. When at idle the Relief solenoid passes vacuum to the ACV to keep air pump air from dumping out the passage to the silencer. As you step on the throttle the TPS value changes and thereby de energizes the Relief solenoid and prevents vacuum going to the ACV's relief diaphram resulting in the airpump air now being dumped into the silencer in the right front fender.
On a old ACV you can expect some air coming out the large port on the ACV. Enough you can feel it, but when the vacuum from the Relief solenoid is not going to the ACV, then a large and noticable amount of air can be felt leaving the large port on the ACV.
I realize now I need to re read the FSM about steps 12 and 13. Makes no sense to me right now since at idle there should be no vacuum leaving the Switching solenoid going to the ACV therefore there would be no change in the air coming from the Split air pipe. Makes no sense.
I'll go re read the FSM for 88 NON TURBO cars and maybe write back.
Usually if I want to see if my ACV is working or not................warm the engine up. Remove the large hose on the ACV that connects the ACV to the silencer in the right fender.......reach over and pull the ELECTRICAL plug off the RELIEF (blue) solenoid while at the same time holding a finger over the large relief port on the ACV. The result of pulling the electrical plug off the RELIEF solenoid is to stop vacuum going the ACV and therefore letting most all of the airpump air to dump overboard to the silencer in the fender. Try this and see if it works.
On a NON TURBO there are two vacuum hose jusrt above the ACV. One vacuum hose comes from the Relief solenoid and the other from the Switching solenoid. Pulling the vacuum hose off at this location is the same as pulling it off the Relief solenoid and is much easier to accomplish.
Page 4A-38 shows the internals of the ACV. It's obvious that there should be NO vacuum coming from the Switching Solenoid to the ACV at IDLE. I say AT IDLE.
So pull those two vacuum hose just above the ACV off when at idle and make sure only ONE have vacuum on the vacuum hose. I forget which of those two is the swiching vacuum hose and which the Relief vacuum hose right now. Satch knows.. I can never remember. Sometimes these two hose get crossed up and results are the ACV does not work like it should.
At idle ALL the airpump air should be going DOWN to the exhaust ports AT the engine exhaust port and NONE going to the split air pipe and non going to the silencer.
Some of the above should make sense. It all made sense to me when I wrote it.
The proper setting of the TPS decides if the Switching and Relief solenoids are energized or not energized at idle. Normal output of the TPS is ONE VOLT dc at idle with a fully warmed up engine.
When the engine is COLD the Relief solenoid will be de energized til the water temp allows the TPS to come to its idle positon putting out ONE VOLT DC to the ECU which in turn will put a gnd on the Relief solenoid to allow it to pass vacuum to the ACV .
That TPS is one volt dc approx so if you output say 0.95 vdc or 1.05 vdc it will work just fine and dandy as putting out exactly one volt dc. You can be even further off than those two figures for it to work right. Approx is approx is approx is approx.
Step number 13: from the port that the split air hose was attached to. You will feel very little air when doing this FYI. Almost just a wisp of air. This step is not as essential as the step eight where there should be a very noticable increase in the air coming out the ACV relief port (where the large hose going to the silencer attaches.
ACV solenoids do very much nothing. The ACV is controlled by the Relief (blue) and Switching (grey) solenoids. When at idle the Relief solenoid passes vacuum to the ACV to keep air pump air from dumping out the passage to the silencer. As you step on the throttle the TPS value changes and thereby de energizes the Relief solenoid and prevents vacuum going to the ACV's relief diaphram resulting in the airpump air now being dumped into the silencer in the right front fender.
On a old ACV you can expect some air coming out the large port on the ACV. Enough you can feel it, but when the vacuum from the Relief solenoid is not going to the ACV, then a large and noticable amount of air can be felt leaving the large port on the ACV.
I realize now I need to re read the FSM about steps 12 and 13. Makes no sense to me right now since at idle there should be no vacuum leaving the Switching solenoid going to the ACV therefore there would be no change in the air coming from the Split air pipe. Makes no sense.
I'll go re read the FSM for 88 NON TURBO cars and maybe write back.
Usually if I want to see if my ACV is working or not................warm the engine up. Remove the large hose on the ACV that connects the ACV to the silencer in the right fender.......reach over and pull the ELECTRICAL plug off the RELIEF (blue) solenoid while at the same time holding a finger over the large relief port on the ACV. The result of pulling the electrical plug off the RELIEF solenoid is to stop vacuum going the ACV and therefore letting most all of the airpump air to dump overboard to the silencer in the fender. Try this and see if it works.
On a NON TURBO there are two vacuum hose jusrt above the ACV. One vacuum hose comes from the Relief solenoid and the other from the Switching solenoid. Pulling the vacuum hose off at this location is the same as pulling it off the Relief solenoid and is much easier to accomplish.
Page 4A-38 shows the internals of the ACV. It's obvious that there should be NO vacuum coming from the Switching Solenoid to the ACV at IDLE. I say AT IDLE.
So pull those two vacuum hose just above the ACV off when at idle and make sure only ONE have vacuum on the vacuum hose. I forget which of those two is the swiching vacuum hose and which the Relief vacuum hose right now. Satch knows.. I can never remember. Sometimes these two hose get crossed up and results are the ACV does not work like it should.
At idle ALL the airpump air should be going DOWN to the exhaust ports AT the engine exhaust port and NONE going to the split air pipe and non going to the silencer.
Some of the above should make sense. It all made sense to me when I wrote it.
The proper setting of the TPS decides if the Switching and Relief solenoids are energized or not energized at idle. Normal output of the TPS is ONE VOLT dc at idle with a fully warmed up engine.
When the engine is COLD the Relief solenoid will be de energized til the water temp allows the TPS to come to its idle positon putting out ONE VOLT DC to the ECU which in turn will put a gnd on the Relief solenoid to allow it to pass vacuum to the ACV .
That TPS is one volt dc approx so if you output say 0.95 vdc or 1.05 vdc it will work just fine and dandy as putting out exactly one volt dc. You can be even further off than those two figures for it to work right. Approx is approx is approx is approx.
05-31-12, 05:25 PM
#15
Rotary Freak
Satch up there a few posts ago says both vacuum should have vacuum on them (the two lines just above the ACV). Hmmmmmm. Maybe he's not right this one time? I'll go take a look but from what I remember only one should have vacuum (the relief one). Makes no sense to me for both having vacuum at idle.
Lot of people wrote post since I started scribbling. Sorry 'bout that folks.
Lot of people wrote post since I started scribbling. Sorry 'bout that folks.
05-31-12, 05:41 PM
#17
Satch up there a few posts ago says both vacuum should have vacuum on them (the two lines just above the ACV). Hmmmmmm. Maybe he's not right this one time? I'll go take a look but from what I remember only one should have vacuum (the relief one). Makes no sense to me for both having vacuum at idle.
Lot of people wrote post since I started scribbling. Sorry 'bout that folks.
Lot of people wrote post since I started scribbling. Sorry 'bout that folks.
------------------------------------------------------------------------
The BLUE solenoid is responsible for supplying the ACV with vacuum to the Relief diaphram in the ACV.
The solenoids are almost bullet proof. At idle it is energized. It has 12v on it any time the key is to ON. It has a ground on it when the TPS is set right and the engine is at idle. The ECU puts that ground on it IF the TPS is set right.
If you pull the plug off the Relief Solenoid it STOPS supplying the acv with vacuum to the relief diaphram in the acv. The airpump air then dumps overboard.
All you have to do to prove the solenoid is good/bad is to idle the car. When fully warm/hot, pull the two vacuum lines off that are just above the acv. Both should have vacuum on them. One is from the Relief solenoid and the other from the Switching solenoid. The Relief solenoid is just a gate for vacuum to the acv's relief diaphram. Energized you have a path of vacuum to the ACV. De-energized cuts the path of vacuum.
The only reasonable cause for the idle to drop 200 rpm when the BLUE plug is pulled is............the ACV's anti-afterburn diaphram is busted and leaking air into the intake. It's putting that air into the intake under the pressue of the air pump. If you disable the Relief solenoid to dump that pressurized air in the acv overboard so now the leaking diaphram isn't letting air into the intake as much as before.
I'm sure there are other opinions out there.
To determine which is which, pull the plug (Blue) off the Relief solenoid. One of the two vacuum lines above the acv should now lose its vacuum. That one will be the one from the Relief solenoid.
05-31-12, 05:53 PM
#18
Rotary Freak
My bad. BOTH vac hose just above the ACV should have vacuum at idle.
Rear hose is from the Relief solenoid and the front hose is from the Switching solenoid.
At idle the Relief solenoid is energized and passes vaccum in this condition. At idle the Switching solenoid is de energized and passes vaccum in this condition because those two solenoids are configured differently (configured means the small filter on them is connected to a different nipple on the solenoid and therefore the hose are connected differently).
So I guess I was WRONG in that if the vacuum is removed from the swtiching solenoid the result will be a small increase in the air coming from the split air pipes nipple.
Its so much easier removing the vacumm hose at the ACV rather than the solenoids themselves. Same result will happen.
Also the removal of the elect plug off the Relief solenoid will indeed result in lack of vacuum to the ACV's relief diaphram resulting in much more air flow out the large port on the ACV. If this happens most likely the ACV is functional.
At idle you want the airpump air to go to the exhaust PORTs and not being dumped overboard to the silencer. This airpump aiir will mix with the exhaust gasses leaving the engine and dilute the afr prior to the catalytic converter (something desired for emissioins testing).
Sorry 'bout the couple of errors above in the other posts of mine.
Rear hose is from the Relief solenoid and the front hose is from the Switching solenoid.
At idle the Relief solenoid is energized and passes vaccum in this condition. At idle the Switching solenoid is de energized and passes vaccum in this condition because those two solenoids are configured differently (configured means the small filter on them is connected to a different nipple on the solenoid and therefore the hose are connected differently).
So I guess I was WRONG in that if the vacuum is removed from the swtiching solenoid the result will be a small increase in the air coming from the split air pipes nipple.
Its so much easier removing the vacumm hose at the ACV rather than the solenoids themselves. Same result will happen.
Also the removal of the elect plug off the Relief solenoid will indeed result in lack of vacuum to the ACV's relief diaphram resulting in much more air flow out the large port on the ACV. If this happens most likely the ACV is functional.
At idle you want the airpump air to go to the exhaust PORTs and not being dumped overboard to the silencer. This airpump aiir will mix with the exhaust gasses leaving the engine and dilute the afr prior to the catalytic converter (something desired for emissioins testing).
Sorry 'bout the couple of errors above in the other posts of mine.
05-31-12, 06:10 PM
#19
Rotary Freak
For what it's worth: on my 86 na I also notice a 150 rpm drop when pulling the elect plug off the ACV.
I know my ACV is working 'cause the loss of vacuum results in a large increase in the air coming out the large dump port on the ACV to the silence nipple.
Putting a finger over the vacuum hose and the drop of rpm stays the same...lower. So it's not a vacuum leake etc causing the lower rpms at idle).
My cars pass emissions very well thank you so I know the thing is working right. The loss of rpm when the blue relief solenoid is disconnected (cuts vacuum to the relief diaphram in the ACV) isn't easily explained and not to worry about imho since the relief solenoid de energizes when you put your foot to the pedal and are driving the car (on the whole).
In the past I've thought this might be caused by the airpump air going to the exhaust ports gets some of that air sucked into the INTAKE "stroke" of the rotor. So removing that "air" or adding that 'Air" would make a change in idle speed.
Seems I'd just look at my afrs to prove/disprove that. Not today though.
Again..........I'd not worry about that loss of rpm at idle when the relief solenoids plug is pulled. Not a normal thing to happen in everyday life.
I remeber years ago having doubts about the air coming out the split air port when doing the test. I got a long piece of rubber hose and attached it to the split air port and put the other end in a pot of water. Idled the engine and looked at the hose in the water. Then pulled the vac hose for the switchig solenoid and wallla, big bubbles in the pan of water.
Vacuum on the switching diaphram results in the valve closing off the passage to the split air pipe. Removing the source of vacuum lets teh passage to the split air pipe open and air go to the split air pipe/converter. See the view of the ACV I mentioned earlier in another post.
I know my ACV is working 'cause the loss of vacuum results in a large increase in the air coming out the large dump port on the ACV to the silence nipple.
Putting a finger over the vacuum hose and the drop of rpm stays the same...lower. So it's not a vacuum leake etc causing the lower rpms at idle).
My cars pass emissions very well thank you so I know the thing is working right. The loss of rpm when the blue relief solenoid is disconnected (cuts vacuum to the relief diaphram in the ACV) isn't easily explained and not to worry about imho since the relief solenoid de energizes when you put your foot to the pedal and are driving the car (on the whole).
In the past I've thought this might be caused by the airpump air going to the exhaust ports gets some of that air sucked into the INTAKE "stroke" of the rotor. So removing that "air" or adding that 'Air" would make a change in idle speed.
Seems I'd just look at my afrs to prove/disprove that. Not today though.
Again..........I'd not worry about that loss of rpm at idle when the relief solenoids plug is pulled. Not a normal thing to happen in everyday life.
I remeber years ago having doubts about the air coming out the split air port when doing the test. I got a long piece of rubber hose and attached it to the split air port and put the other end in a pot of water. Idled the engine and looked at the hose in the water. Then pulled the vac hose for the switchig solenoid and wallla, big bubbles in the pan of water.
Vacuum on the switching diaphram results in the valve closing off the passage to the split air pipe. Removing the source of vacuum lets teh passage to the split air pipe open and air go to the split air pipe/converter. See the view of the ACV I mentioned earlier in another post.
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