idle issues, in need of some help
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idle issues, in need of some help
I'm kinda stumped about this one. I have the dreaded idle issue that's going up and down and up and down....it's on a 93 honda accord first of all, I did the usual bleeding to the car, checked for any vacuum leaks- didn't find any, replaced the iacv. I know the usual cause is the fitv, but it works as it should. I took it off and tested it, cools off it opens- it heats up it closes. What I'm confused about is the channels in the throttle body. I know the upper is the iacv and the lower is the fitv. Question 1- I assumed the fitv was bad so I blocked it off temporary till I get a new one, thinking it'll stop the idle issue. When I block it off there shouldn't be any Sucks on right? But there no chance at all!! Is that normal, or is there an issue with the intake manifold? Question 2- the iacv, at idling is it supposed to give suction - or only when it calls for it like when the ac is on. I'm fairly fluent with vehicles, but this is kinda racking my brain
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From: East Coast 506, Canada
Re: idle issues, in need of some help
If you have the FIT valve opening blocked off on the manifold there should be no suction on the inlet side on the throttle body. If I'm not mistaken isn't the FITV opening on the top for the 90-93 F22A* Accord chassis? I know it is on bottom for the 94-97 F22B* Accords. I thought I remembered someone telling me they were opposite between the 2.
It has been my experience that there is usually a bit of suction on the IACV inlet during idle conditions.
Any time I get an idle issue like this, first thing I do is pull of the intake tube and I plug the IAC and FIT inlet openings individually and see if it makes any difference. Then go from there. Another area to look at on these older Accords is the idle air boost valve. It is located on the drivers end of the intake manifold.
Was there any other issues leading up to this one? Had you been working on something in the engine bay or did it just come out of nowhere?
It has been my experience that there is usually a bit of suction on the IACV inlet during idle conditions.
Any time I get an idle issue like this, first thing I do is pull of the intake tube and I plug the IAC and FIT inlet openings individually and see if it makes any difference. Then go from there. Another area to look at on these older Accords is the idle air boost valve. It is located on the drivers end of the intake manifold.
Was there any other issues leading up to this one? Had you been working on something in the engine bay or did it just come out of nowhere?
B*a*n*n*e*d
Joined: Dec 2008
Posts: 12,028
Likes: 5
Re: idle issues, in need of some help
If you have the FIT valve opening blocked off on the manifold there should be no suction on the inlet side on the throttle body. If I'm not mistaken isn't the FITV opening on the top for the 90-93 F22A* Accord chassis? I know it is on bottom for the 94-97 F22B* Accords. I thought I remembered someone telling me they were opposite between the 2.
It has been my experience that there is usually a bit of suction on the IACV inlet during idle conditions.
Any time I get an idle issue like this, first thing I do is pull of the intake tube and I plug the IAC and FIT inlet openings individually and see if it makes any difference. Then go from there. Another area to look at on these older Accords is the idle air boost valve. It is located on the drivers end of the intake manifold.
Was there any other issues leading up to this one? Had you been working on something in the engine bay or did it just come out of nowhere?
It has been my experience that there is usually a bit of suction on the IACV inlet during idle conditions.
Any time I get an idle issue like this, first thing I do is pull of the intake tube and I plug the IAC and FIT inlet openings individually and see if it makes any difference. Then go from there. Another area to look at on these older Accords is the idle air boost valve. It is located on the drivers end of the intake manifold.
Was there any other issues leading up to this one? Had you been working on something in the engine bay or did it just come out of nowhere?
MM Gruppe B
Joined: Feb 2009
Posts: 7,028
Likes: 110
From: 94577/Gaillimh
Re: idle issues, in need of some help
IACV acts as a mini throttle body to more accurately control idle rpm under load, be it from steering input(pressure sensor on pump) A/C turned on, or just loading the engine in gear all controlled by the ECU.
FITV is for warmup(similar function to a choke on carbs). It will allow air to pass through until the coolant heats up enough to close the valve and bring the idle speed down, at which point the IACV takes over. It is not controlled by the ECU.
As Ghost mentioned, blocking either off will eliminate them as a source of idle hunting. You will want to check any other potential vacuum leaks. Brake booster, 'boost valve' on the intake, or any of the vacuum hoses found on the car, check the last thing worked on or a nearby component. If a hose/nipple was stretched/cracked it may cause a vacuum leak.
FITV is for warmup(similar function to a choke on carbs). It will allow air to pass through until the coolant heats up enough to close the valve and bring the idle speed down, at which point the IACV takes over. It is not controlled by the ECU.
As Ghost mentioned, blocking either off will eliminate them as a source of idle hunting. You will want to check any other potential vacuum leaks. Brake booster, 'boost valve' on the intake, or any of the vacuum hoses found on the car, check the last thing worked on or a nearby component. If a hose/nipple was stretched/cracked it may cause a vacuum leak.
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