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Old 05-25-2018, 06:25 PM   #1
CarbonFibreGuy
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Bottomed out idle screw+Unplugged IACV= Still running?

Title. A week ago I turned her on and the idle started jumping from 1k to 1.5k to warm up. Didn't do anything about it until today, when I was setting the base idle again, and while the car is warmed up, the idle screw is bottomed out, and the IACV is unplugged, still running at 1k RPMs. Anyone have any insight to why this might be? I suspect a vacuum leak but I've never dealt with one of those before.

F22A6, 5SPD, no mods, engine held idle beautifully until just last week with no issues.

Edit: Nevermind, looks like I have a vacuum leak somewhere. Going to be looking for it now.

Last edited by CarbonFibreGuy; 05-25-2018 at 06:42 PM.
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Old 05-25-2018, 06:54 PM   #2
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If it is that big a leak, you may actually be able to hear it. Typical place for surging idle is the FITV - new o-ring on the yellow piston should fix this. I had a large leak past the o-ring on the idle adjusting screw - new o-ring fixed that.
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Old 05-26-2018, 06:52 AM   #3
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Use some brake cleaner or carburetor cleaner etc, spray around intake and all vacuum hoses with the engine running, if there is a noticeable change in rpm when spraying a certain spot there is your vacuum leak, soapy water also works, a hunting idle is caused by the ecu shutting off the fuel injectors,actual and desired rpm based off of throttle angle, MAP sensor and engine coolant temp. are too far apart, find the vacuum leak, a smoke machine can also be used but not everyone has one hehehe. A stuck open IAC valve will also cause this issue
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Old 05-26-2018, 09:45 AM   #4
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Quote:
Originally Posted by fleetw00d View Post
If it is that big a leak, you may actually be able to hear it. Typical place for surging idle is the FITV - new o-ring on the yellow piston should fix this. I had a large leak past the o-ring on the idle adjusting screw - new o-ring fixed that.
Unfortunately I can't get around anywhere, so I'm going to put it all back together and spread some RTV where the FITV meets the plenum as a temporary seal. The piston o-ring looks to be okay, if a little dry. I also took out the vacuum control box (is that what it's called? Above the fuel filter.) and so far there aren't any hoses that look cracked or bad. The PCV hose, however, actually did break at the end where it meets the plenum, and while the rest of it looks okay, I'm debating whether I should buy a new one and replace it.

So far, the plan is to find the o-rings at the dealer once its' all put back together, and grab some hose line from vatozone and replace the PCV line minimum.

Quote:
Originally Posted by Ashtrain View Post
Use some brake cleaner or carburetor cleaner etc, spray around intake and all vacuum hoses with the engine running, if there is a noticeable change in rpm when spraying a certain spot there is your vacuum leak, soapy water also works, a hunting idle is caused by the ecu shutting off the fuel injectors,actual and desired rpm based off of throttle angle, MAP sensor and engine coolant temp. are too far apart, find the vacuum leak, a smoke machine can also be used but not everyone has one hehehe. A stuck open IAC valve will also cause this issue
How would I be able to tell if the IACV is stuck open? I've replaced the FITV and IACV about two years ago with used units, but I really can't remember how I founf out the old one is open. Don't have access to a multimeter here unfortunately--I might need to go see the older dude to have access to the tools.

I will try the brake cleaner suggestion, as soon as its' put back together and warmed up.

Last edited by CarbonFibreGuy; 05-26-2018 at 09:53 AM.
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Old 05-26-2018, 11:45 AM   #5
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Okay, I put her back together and no difference. However, something I noticed now is that if I try to apply constant acceleration, it is erratic and can't hold it, almost like as if something is blocking it from keeping it steady. This is in neutral and not under load:

Say I hold it at 1500 RPMs, it'll wave in between that +/- 75RPMs. She'll run, just not steady, and the problem is the same regardless of the IACV plugged in or not, so I am thinking it may be the FITV I need to replace. However, it looks like only Honda makes 'em.

Any insight or suggestions I need?
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Old 05-26-2018, 08:57 PM   #6
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You don't need to replace the FITV - repair it. If the o-ring is dry, it is not sealing. http://www.cb7tuner.com/vbb/showthread.php?t=206012

A new gasket for between the FITV and plenum from Honda is a good idea.
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Old 05-27-2018, 06:43 PM   #7
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DO NOT use brake cleaner or carb cleaner to try and find a vaccum leak......unless you like the possibility of fire. Good rule of thumb is do not spray flammable liquids on an engine while running, the heat could combust it, the ignition could combust it. DON'T DO IT! Water in a regular spray bottle works just as well. Safety first ALL the time, NO exceptions!
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Old 05-30-2018, 11:19 AM   #8
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Quote:
Originally Posted by fleetw00d View Post
You don't need to replace the FITV - repair it. If the o-ring is dry, it is not sealing. http://www.cb7tuner.com/vbb/showthread.php?t=206012

A new gasket for between the FITV and plenum from Honda is a good idea.
Happen to have a part number for the gasket? I only see that it uses an elongated oring, which I will order.

I did wrap a new oring around the piston, but the problem persists. I however, have a very serious problem right now--The engine is knocking, and its' only getting worse. I don't know how the fuck this happened, in layman terms. I'm going to order the orings before the day clears, and pray that it comes in before the weekend.

One thing is for sure is that I'm burning fuel like crazy, so I'm thinking the car is running too lean thanks to the added air leak coming from who knows where--would running too lean cause knocking?

I'm absolutely in awe more than anything that it's going downhill without any sign of stopping. I have not changed anything aside from the oring on the piston, however, I did have trouble screwing it down.
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Old 05-30-2018, 09:44 PM   #9
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Yeah, it isn't really gasket, it is two o-rings. The upper is an oval from Honda, but a round one from the hardware store will fit. The lower one is more important because that seals the lower connection (the top of the FITV is ported to upstream of the throttle plate, the lower portion feeds the plenum) which if it leaks allows air into the plenum downstream of the throttle plate.

How tight is your throttle cable? There is supposed to be some slack in it at closed throttle to allow the throttle plate to fully close. Try blocking off the FITV and start boost valve (on the left end of the intake plenum) completely (just put a piece of electrical tape over the ports and reinstall them) to be sure they aren't the source of the leak. Also try blocking the PCV valve. Use a pair of pliers to clamp off all the vacuum lines to the plenum one by one, including the hose to the power brake booster; if the idle drops when you pinch one off, then there is a leak in that part of vacuum circuit.
Does the idle drop any when you unplug the IACV?
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Old 05-30-2018, 11:57 PM   #10
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Quote:
Originally Posted by fleetw00d View Post
Yeah, it isn't really gasket, it is two o-rings. The upper is an oval from Honda, but a round one from the hardware store will fit. The lower one is more important because that seals the lower connection (the top of the FITV is ported to upstream of the throttle plate, the lower portion feeds the plenum) which if it leaks allows air into the plenum downstream of the throttle plate.

How tight is your throttle cable? There is supposed to be some slack in it at closed throttle to allow the throttle plate to fully close. Try blocking off the FITV and start boost valve (on the left end of the intake plenum) completely (just put a piece of electrical tape over the ports and reinstall them) to be sure they aren't the source of the leak. Also try blocking the PCV valve. Use a pair of pliers to clamp off all the vacuum lines to the plenum one by one, including the hose to the power brake booster; if the idle drops when you pinch one off, then there is a leak in that part of vacuum circuit.
Does the idle drop any when you unplug the IACV?
Throttle cable is fine, its' got some slack in it for this reason. I keep an eye on it every now and then with the rest of the engine for the most part to ensure its' not going to be a problem.

I'm dead in the water right now, I unplugged the IACV and she wouldn't hold anything remotely close to an idle. I plugged it back in and same thing, both times the engine idles just dropped lower than they did before. I tried getting her to run in gear, but both 1st and 2nd are completely erratic and I can't risk driving it like this.

One thing I noticed while driving it today before these things was that there is a noise that sounds like a bird chirping continuously that wasn't there before--only during acceleration. Not sure what thats' up to, but I get the feeling it's coming from the same place as the one that sounds like a duck being deflated after takeoff.

Keep in mind the idle speed screw is still turned all the way down, and I replaced the oring to the yellow piston and tightened it as far as I could, but it did not bottom out.

I'm going to tape up the FITV and the ABV as soon as the car is towed to the house, then we'll see, thanks.
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Old 07-20-2018, 10:38 PM   #11
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Ever get this figured out?
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Old 08-15-2018, 06:50 PM   #12
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Originally Posted by fleetw00d View Post
Ever get this figured out?
Hey dude, I still haven't. Times got rough.

I still have the car, but instead of it just being a vacuum leak somewhere in the system, then this sound popped up while driving one day:

https://www.youtube.com/watch?v=FGDeysctgzw

I did replace the plunger for the FITV (or altogether, it's been so long already), I really can't remember what else I replaced. I also replaced the plug wires, the distributor cap, and the rotor.

Interesting thing about the cap--On the inside where the plug goes into, the metal contact was burned off, like as if too much current had been ran through it. Replacing them however did not fix the issue, so maybe when I replace the spark plug (not sure if they were compromised, but I bought a set anyways), there will be an improvement.

The battery is being recharged right now, so once its' complete I'll stick it in the car again. At some point I'm pretty sure I had an engine code but I'm not really sure, I just remember the car not working as it should. If I did have the money, I would have k-swapped it last month, but, money has come tight.

I'll keep the thread updated, but for now the plan is to replace every. single. vacuum hose. Then, replace spark plugs (they had oil in the channels, leaking from the valve cover gasket), and go from there.

Thank you. Any ideas are greatly welcomed.
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Old 08-16-2018, 10:57 PM   #13
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Not sure the sound is deep enough sounding to be rod knock - can you tell where it is coming from? How many miles on the engine? Oil level up to snuff? The oil in the tube wells is not so much from the valve cover seals as it is from the seals under the camshaft/rocker assembly mounts. You have to remove this whole assembly to replace the seals.
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Old 09-19-2018, 10:02 PM   #14
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Originally Posted by fleetw00d View Post
Not sure the sound is deep enough sounding to be rod knock - can you tell where it is coming from? How many miles on the engine? Oil level up to snuff? The oil in the tube wells is not so much from the valve cover seals as it is from the seals under the camshaft/rocker assembly mounts. You have to remove this whole assembly to replace the seals.
This is the most recent edit, to keep this thread from bumping up too much. I changed out the spark plugs and ensured that the spark plug channels were clear. Still same sound, still rhythmic loss of power.

I agree, it also doesn't sound as rough like I've heard on other videos I'v heard on rod knock. It just suddenly started making that sound one day out of nowhere.

The engine since its' rebuild is less than 15k. I replaced the valve seals, main seals, head gasket, crankshaft, bearing metals, oil rings, and some other stuff.

I for sure have a leak in the valve cover gasket (again, this Felpro one is the third to go into this car), and there is definitely a bit of oil going into the spark plug channels and covering the tops of the contacts--I cleaned it a few days ago but I didn't bother trying to start it. I'm replacing the spark plugs now just in case they may have been compromised by having oil on top of them,and if she runs then I'll grab a new valve cover gasket seal set from some place other than Felpro.

She actually does have a bit more oil than what's required, a small leak as well but still plenty in the pan.

I'm going to look for a diagram of the seals you mentioned underneath the camshaft assembly, I'm sure I replaced them but I'd like to remember for sure.

I also found a diagram of where all the vacuum lines are and plan on replacing them all tomorrow for sure, if not Friday. Going through it tough right now--Have to help my mom fix her car, the exhaust manifold needs to be welded due to it having a crack., pre oxygen sensor that's making the car second guess itself a lot.

Last edited by CarbonFibreGuy; 09-19-2018 at 11:47 PM.
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