Should Throttle Body be closed completely at idle?
08-13-2008, 09:03 AM
#1
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Should Throttle Body be closed completely at idle?
I'm having a discussion about this somewhere else, and they are telling me TB should be adjusted so that it is fully closed at Idle. And the IAC is what does all the work. But I disagreed with them and said that TB butterfly is what adjusts base RPM through the idle adjust screw, and therefore should be open partly. The IAC valve then maintains that base RPM (such as say 700) as engine conditions change.
Even in the shop manual it tells you to adjust using TB idle screw if out of spec!
Even in the shop manual it tells you to adjust using TB idle screw if out of spec!
08-13-2008, 09:06 AM
#2
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Re: Should Throttle Body be closed completely at idle? (Cleft_Asunder)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Cleft_Asunder »</TD></TR><TR><TD CLASS="quote">I'm having a discussion about this somewhere else, and they are telling me TB should be adjusted so that it is fully closed at Idle. And the IAC is what does all the work. But I disagreed with them and said that TB butterfly is what adjusts base RPM through the idle adjust screw, and therefore should be open partly. The IAC valve then maintains that base RPM (such as say 700) as engine conditions change.
Even in the shop manual it tells you to adjust using TB idle screw if out of spec!</TD></TR></TABLE>
no the TB should not completely closed while on idle. if so, the motor will shut off.
Even in the shop manual it tells you to adjust using TB idle screw if out of spec!</TD></TR></TABLE>
no the TB should not completely closed while on idle. if so, the motor will shut off.
08-13-2008, 09:15 AM
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Re: Should Throttle Body be closed completely at idle? (philosofy1)
Yes but they are arguing that TB should be closed, while all air flows through IAC, which is controlled by ECU.
08-13-2008, 09:34 AM
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Re: Should Throttle Body be closed completely at idle? (Cleft_Asunder)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Cleft_Asunder »</TD></TR><TR><TD CLASS="quote">Yes but they are arguing that TB should be closed, while all air flows through IAC, which is controlled by ECU.</TD></TR></TABLE>
stop wasting your timing arguing with ignorant people. if the TB is closed completely, then the motor will shut off. on idle the butterfly has to be slightly open, just enough to let the motor breath.
stop wasting your timing arguing with ignorant people. if the TB is closed completely, then the motor will shut off. on idle the butterfly has to be slightly open, just enough to let the motor breath.
08-13-2008, 11:40 AM
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Re: Should Throttle Body be closed completely at idle? (Cleft_Asunder)
Guys, idle adjust screw (the one with the plastic cap on it) adjust TB butterfly, NOT IAC air flow right??
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08-13-2008, 12:58 PM
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Re: Should Throttle Body be closed completely at idle? (Cleft_Asunder)
Well, I may have confused you guys. But whatever the case, the reality seems to be that TB should be closed during idle completely, while the IAC takes over. If the TB is open, then you will get an idle air control system light because the ECU thinks there is a leak.
I don't know, just read this if you're interested:
http://www.civicforums.com/for...38733
I don't know, just read this if you're interested:
http://www.civicforums.com/for...38733
08-13-2008, 01:00 PM
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Re: Should Throttle Body be closed completely at idle? (philosofy1)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by philosofy1 »</TD></TR><TR><TD CLASS="quote">
stop wasting your timing arguing with ignorant people. if the TB is closed completely, then the motor will shut off. on idle the butterfly has to be slightly open, just enough to let the motor breath.</TD></TR></TABLE>
Not true. IAC valve is an air route from above butterfly, to below it. It takes over the butterflies job of rugulating air. The IAC is needed to keep airflow constant based on changing variables. ECU takes readings from sensors throughout car, and sends them to IAC, which adjust valve constantly to maintain (roughly) "X" RPM. Without the IAC valve, rpm would surge up and down.
Modified by Cleft_Asunder at 2:24 PM 8/13/2008
stop wasting your timing arguing with ignorant people. if the TB is closed completely, then the motor will shut off. on idle the butterfly has to be slightly open, just enough to let the motor breath.</TD></TR></TABLE>
Not true. IAC valve is an air route from above butterfly, to below it. It takes over the butterflies job of rugulating air. The IAC is needed to keep airflow constant based on changing variables. ECU takes readings from sensors throughout car, and sends them to IAC, which adjust valve constantly to maintain (roughly) "X" RPM. Without the IAC valve, rpm would surge up and down.
Modified by Cleft_Asunder at 2:24 PM 8/13/2008
08-13-2008, 01:15 PM
#10
Former Moderator
Re: Should Throttle Body be closed completely at idle? (Cleft_Asunder)
In theory the butterfly in the TB should be closed at idle. The reason the engine doesn't shut off is there is an idle circuit and an idle mixture screw port that can be adjusted to bleed more air into the IM that bypasses the butterfly altogether.
Some older Hondas also have a throttle stop screw that allows you to manually adjust where the butterfly stops, and many times when there is an idle issue unexperienced "techs" or "uncle Bob" adjust the stop screw instead of trying to figure out the real issue.
It's not the easiest concept to wrap your head around, but basically there are other ways that the engine ingests air into the IM besides the actual TB plate.
Some older Hondas also have a throttle stop screw that allows you to manually adjust where the butterfly stops, and many times when there is an idle issue unexperienced "techs" or "uncle Bob" adjust the stop screw instead of trying to figure out the real issue.
It's not the easiest concept to wrap your head around, but basically there are other ways that the engine ingests air into the IM besides the actual TB plate.
08-13-2008, 01:47 PM
#12
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Re: Should Throttle Body be closed completely at idle? (Cleft_Asunder)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Cleft_Asunder »</TD></TR><TR><TD CLASS="quote">Yeah, it's called the IAC valve. Why are you beating around the bush?</TD></TR></TABLE>
Are you talking to me?
I mean if you want to get technical I didn't see you include the fast idle valve circuit on the 95-older Hondas either. I mean are we going to try and outwit each other on a topic that you started with a misconception about how the TB plate works at idle?
The IACV is not THE sole way an IM gets air besides the TB plate. How would an IACV injest air into the IM without the aid of other items? It doesn't have it's own air injection port, does it? No it doesn't. Also how would you explain unplugging an IACV and an engine still running, even with the plate closed at idle?
Are you talking to me?
I mean if you want to get technical I didn't see you include the fast idle valve circuit on the 95-older Hondas either. I mean are we going to try and outwit each other on a topic that you started with a misconception about how the TB plate works at idle?
The IACV is not THE sole way an IM gets air besides the TB plate. How would an IACV injest air into the IM without the aid of other items? It doesn't have it's own air injection port, does it? No it doesn't. Also how would you explain unplugging an IACV and an engine still running, even with the plate closed at idle?
08-13-2008, 02:31 PM
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Re: Should Throttle Body be closed completely at idle? (B18C5-EH2)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B18C5-EH2 »</TD></TR><TR><TD CLASS="quote">
Are you talking to me?
I mean if you want to get technical I didn't see you include the fast idle valve circuit on the 95-older Hondas either. I mean are we going to try and outwit each other on a topic that you started with a misconception about how the TB plate works at idle?
The IACV is not THE sole way an IM gets air besides the TB plate. How would an IACV injest air into the IM without the aid of other items? It doesn't have it's own air injection port, does it? No it doesn't. Also how would you explain unplugging an IACV and an engine still running, even with the plate closed at idle?
</TD></TR></TABLE>
What are you talking about? The IAC doesn't INJECT air into the IM, it is a bypass route and works based on engine vaccum. So your question of how the IAC would injest air into the IM is absurd. It's all vacuum based. The IAC is just a mechanical device, while the electronics on it manipulate the mechanism to open/close to a certain specification to maintain "x" amount of air to maintain "x" amount of RPM.
Yes, IAC is the only air inlet besides small leaks (if any) in the TB while it's closed.
How would I explain unplugging IAC valve which results in RPM increase? Easily. The directions from ECU are no longer there, and therefore the mechanism freely moves into the open position.
Are you talking to me?
I mean if you want to get technical I didn't see you include the fast idle valve circuit on the 95-older Hondas either. I mean are we going to try and outwit each other on a topic that you started with a misconception about how the TB plate works at idle?
The IACV is not THE sole way an IM gets air besides the TB plate. How would an IACV injest air into the IM without the aid of other items? It doesn't have it's own air injection port, does it? No it doesn't. Also how would you explain unplugging an IACV and an engine still running, even with the plate closed at idle?
</TD></TR></TABLE>What are you talking about? The IAC doesn't INJECT air into the IM, it is a bypass route and works based on engine vaccum. So your question of how the IAC would injest air into the IM is absurd. It's all vacuum based. The IAC is just a mechanical device, while the electronics on it manipulate the mechanism to open/close to a certain specification to maintain "x" amount of air to maintain "x" amount of RPM.
Yes, IAC is the only air inlet besides small leaks (if any) in the TB while it's closed.
How would I explain unplugging IAC valve which results in RPM increase? Easily. The directions from ECU are no longer there, and therefore the mechanism freely moves into the open position.
08-13-2008, 02:48 PM
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Re: Should Throttle Body be closed completely at idle? (Cleft_Asunder)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Cleft_Asunder »</TD></TR><TR><TD CLASS="quote">How would I explain unplugging IAC valve which results in RPM increase? Easily. The directions from ECU are no longer there, and therefore the mechanism freely moves into the open position.</TD></TR></TABLE>
I have NEVER seen a honda where unplugging the AICV results in an RPM increase. Maybe eventually it will increase since the ECU will have a CEL... which will result in surging idle or generally crappy idle.
When the AICV is unplugged it falls closed. (pull one out and look at it, I've studied several versions) the Idle screw and possibly the FITV takes over.
(check how the idle is set in the Helm, unplug the AICV, adjust idle screw till 400 RPM, plug in AICV, reset CELs)
we're also talking about different engines here, some of them work one way, some work another. Some don't have a FITV.
I have NEVER seen a honda where unplugging the AICV results in an RPM increase. Maybe eventually it will increase since the ECU will have a CEL... which will result in surging idle or generally crappy idle.
When the AICV is unplugged it falls closed. (pull one out and look at it, I've studied several versions) the Idle screw and possibly the FITV takes over.
(check how the idle is set in the Helm, unplug the AICV, adjust idle screw till 400 RPM, plug in AICV, reset CELs)
we're also talking about different engines here, some of them work one way, some work another. Some don't have a FITV.
08-13-2008, 02:55 PM
#15
Former Moderator
Re: Should Throttle Body be closed completely at idle? (Cleft_Asunder)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Cleft_Asunder »</TD></TR><TR><TD CLASS="quote">
What are you talking about? The IAC doesn't INJECT air into the IM, it is a bypass route and works based on engine vaccum. So your question of how the IAC would injest air into the IM is absurd. It's all vacuum based. The IAC is just a mechanical device, while the electronics on it manipulate the mechanism to open/close to a certain specification to maintain "x" amount of air to maintain "x" amount of RPM.
Yes, IAC is the only air inlet besides small leaks (if any) in the TB while it's closed.
How would I explain unplugging IAC valve which results in RPM increase? Easily. The directions from ECU are no longer there, and therefore the mechanism freely moves into the open position.</TD></TR></TABLE>
:smacks forehead:
I find it hilarious that you busted out at first with some whack ideas on how the idle system works, and now all of the sudden you're the expert.
You cannot even comprehend what I type. I was trying to tell YOU that the IACV is not the only way that the IM gets air besides the TB plate itself. You twisted what I said, and then tried to explain the IACV, but failed.
I also never asked why the rpm raises when you unplug the IACV - I don't know where you got that from. I was making a point - you were acting as though the IACV itself is the only reason an engine can idle if the TB plate is completely closed.
Anyways this topic is a one huge cluster...you know.
You started the topic, asked a question, and when others try and chime in to explain it you try to argue with them.
Classic.
What are you talking about? The IAC doesn't INJECT air into the IM, it is a bypass route and works based on engine vaccum. So your question of how the IAC would injest air into the IM is absurd. It's all vacuum based. The IAC is just a mechanical device, while the electronics on it manipulate the mechanism to open/close to a certain specification to maintain "x" amount of air to maintain "x" amount of RPM.
Yes, IAC is the only air inlet besides small leaks (if any) in the TB while it's closed.
How would I explain unplugging IAC valve which results in RPM increase? Easily. The directions from ECU are no longer there, and therefore the mechanism freely moves into the open position.</TD></TR></TABLE>
:smacks forehead:
I find it hilarious that you busted out at first with some whack ideas on how the idle system works, and now all of the sudden you're the expert.
You cannot even comprehend what I type. I was trying to tell YOU that the IACV is not the only way that the IM gets air besides the TB plate itself. You twisted what I said, and then tried to explain the IACV, but failed.
I also never asked why the rpm raises when you unplug the IACV - I don't know where you got that from. I was making a point - you were acting as though the IACV itself is the only reason an engine can idle if the TB plate is completely closed.
Anyways this topic is a one huge cluster...you know.
You started the topic, asked a question, and when others try and chime in to explain it you try to argue with them.
Classic.
08-13-2008, 04:31 PM
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Re: Should Throttle Body be closed completely at idle? (B18C5-EH2)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B18C5-EH2 »</TD></TR><TR><TD CLASS="quote">
:smacks forehead:
I find it hilarious that you busted out at first with some whack ideas on how the idle system works, and now all of the sudden you're the expert.
You cannot even comprehend what I type. I was trying to tell YOU that the IACV is not the only way that the IM gets air besides the TB plate itself. You twisted what I said, and then tried to explain the IACV, but failed.
I also never asked why the rpm raises when you unplug the IACV - I don't know where you got that from. I was making a point - you were acting as though the IACV itself is the only reason an engine can idle if the TB plate is completely closed.
Anyways this topic is a one huge cluster...you know.
You started the topic, asked a question, and when others try and chime in to explain it you try to argue with them.
Classic.</TD></TR></TABLE>
I read your description of the IAC vavle multiple times, and I still don't know where you're coming from. Of course the sole way an IM get's it's air is through the IAC at idle. I'm talking about a 6th gen here. *Edit: Actually there is another circular pocket above the butterfly that sucks air.
"The IACV is not THE sole way an IM gets air besides the TB plate. How would an IACV injest air into the IM without the aid of other items? "
The IM doesn't get air, it allows it to come through or doesn't allow it to come through. The IAC is the same, it is just a route to the IM. There is no injesting of air anywhere, but rather there is a vacuum and the TB/IAC allow X amount of air to be sucked in.
At first I wasn't sure if TB should be open during idle, but now I know it's not. And what was that stuff earlier about it being a theory that the TB should be closed? It's either supposed to be closed, or open, there's no theory behind it, just action.
And my description of the IAC was fine. If not, why not?
The reason I said RPM increases when IAC plug is disconnected is because that is what happened to me yesterday when I unplugged it, but I didn't have the TB setup properly. Regarless, when unplugged the engine will stay on because the IAC valve cannot close fully. There is a 2mmx6mm (or something) gap through which are can ride through.
Modified by Cleft_Asunder at 6:04 PM 8/13/2008
:smacks forehead:
I find it hilarious that you busted out at first with some whack ideas on how the idle system works, and now all of the sudden you're the expert.
You cannot even comprehend what I type. I was trying to tell YOU that the IACV is not the only way that the IM gets air besides the TB plate itself. You twisted what I said, and then tried to explain the IACV, but failed.
I also never asked why the rpm raises when you unplug the IACV - I don't know where you got that from. I was making a point - you were acting as though the IACV itself is the only reason an engine can idle if the TB plate is completely closed.
Anyways this topic is a one huge cluster...you know.
You started the topic, asked a question, and when others try and chime in to explain it you try to argue with them.
Classic.</TD></TR></TABLE>
I read your description of the IAC vavle multiple times, and I still don't know where you're coming from. Of course the sole way an IM get's it's air is through the IAC at idle. I'm talking about a 6th gen here. *Edit: Actually there is another circular pocket above the butterfly that sucks air.
"The IACV is not THE sole way an IM gets air besides the TB plate. How would an IACV injest air into the IM without the aid of other items? "
The IM doesn't get air, it allows it to come through or doesn't allow it to come through. The IAC is the same, it is just a route to the IM. There is no injesting of air anywhere, but rather there is a vacuum and the TB/IAC allow X amount of air to be sucked in.
At first I wasn't sure if TB should be open during idle, but now I know it's not. And what was that stuff earlier about it being a theory that the TB should be closed? It's either supposed to be closed, or open, there's no theory behind it, just action.
And my description of the IAC was fine. If not, why not?
The reason I said RPM increases when IAC plug is disconnected is because that is what happened to me yesterday when I unplugged it, but I didn't have the TB setup properly. Regarless, when unplugged the engine will stay on because the IAC valve cannot close fully. There is a 2mmx6mm (or something) gap through which are can ride through.
Modified by Cleft_Asunder at 6:04 PM 8/13/2008
08-13-2008, 04:33 PM
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Re: Should Throttle Body be closed completely at idle? (Relic1)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Relic1 »</TD></TR><TR><TD CLASS="quote">
I have NEVER seen a honda where unplugging the AICV results in an RPM increase. Maybe eventually it will increase since the ECU will have a CEL... which will result in surging idle or generally crappy idle. *Edit: Actually there is another circular pocket above the butterfly that sucks air.
When the AICV is unplugged it falls closed. (pull one out and look at it, I've studied several versions) the Idle screw and possibly the FITV takes over.
(check how the idle is set in the Helm, unplug the AICV, adjust idle screw till 400 RPM, plug in AICV, reset CELs)
we're also talking about different engines here, some of them work one way, some work another. Some don't have a FITV.</TD></TR></TABLE>
You're right about the first part but there is no true closed position on IAC, at least on a 6th gen. There is always space for air to ride through even when unplugged.
Modified by Cleft_Asunder at 6:03 PM 8/13/2008
I have NEVER seen a honda where unplugging the AICV results in an RPM increase. Maybe eventually it will increase since the ECU will have a CEL... which will result in surging idle or generally crappy idle. *Edit: Actually there is another circular pocket above the butterfly that sucks air.
When the AICV is unplugged it falls closed. (pull one out and look at it, I've studied several versions) the Idle screw and possibly the FITV takes over.
(check how the idle is set in the Helm, unplug the AICV, adjust idle screw till 400 RPM, plug in AICV, reset CELs)
we're also talking about different engines here, some of them work one way, some work another. Some don't have a FITV.</TD></TR></TABLE>
You're right about the first part but there is no true closed position on IAC, at least on a 6th gen. There is always space for air to ride through even when unplugged.
Modified by Cleft_Asunder at 6:03 PM 8/13/2008
08-13-2008, 05:25 PM
#19
Former Moderator
Re: Should Throttle Body be closed completely at idle? (Cleft_Asunder)
Being a moderator requires me to control myself in situations like this where I'd otherwise post rather amusing, insulting remarks.
Hey really quick man have you ever heard of
<FONT SIZE="7">THE IDLE MIXTURE SCREW/PORT</FONT>
???
I mean you could JB weld the freaking IACV ports on an intake manifold, but there will still be idle because of the idle mixture screw! Quit thinking that the IACV is THE sole source of an engine's idle for crying out loud!!!
I'm done with this topic. Do yourself a favor and study the idle circuit in a Helm manual, and stop trying to be an expert just because you read some link on another Civic forum.
Instant experts = amusing
Hey really quick man have you ever heard of
<FONT SIZE="7">THE IDLE MIXTURE SCREW/PORT</FONT>
???
I mean you could JB weld the freaking IACV ports on an intake manifold, but there will still be idle because of the idle mixture screw! Quit thinking that the IACV is THE sole source of an engine's idle for crying out loud!!!
I'm done with this topic. Do yourself a favor and study the idle circuit in a Helm manual, and stop trying to be an expert just because you read some link on another Civic forum.
Instant experts = amusing
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