got a weird IACV problem!... 91' Honda Accord

[khemmo]

Hi guys

Appreciate some help here

I've just been doing some maintenance on my Accord...followed one of the guides here!
I unscrewed the IACV to clean with carby cleaner as it was all gunked up, cleaned it all out!.
I also sprayed some into the throttle body to clean that out too.

When i assembled it all back together and turned the car on first the idle is wayy erratic and now its very low at 300-600 and car shudders quite a bit.
I then noticed this weird noise from the withing the hood...so hard to describe, it sounds like a low pitched electronic 'droning' noise from the air intake.
I took the air filter off and I can actually hear it coming from the throttle body (listening through the air intake pipe). If i disconnect the cable from the IACV that goes to the head the sound stops.
So i did an engine code check and its 14...which means IACV problem?!

I think i may have gotten the cleaner into the black Denso plug unit on the IACV and stuffed it up!

I took it back out and re-cleaned it and checked it...no result.
Any suggestions guys? Might have to get a replacement? I'm in Australia...might be tough haha

Many thanks

[Losiracer2]

yeah man you might need to adjust your idle a bit, depending on how much crap was in your IACV, that could have an affect since its totally clean now vs. dirty and clogged.

[johnl]

When i assembled it all back together and turned the car on first the idle is wayy erratic and now its very low at 300-600 and car shudders quite a bit.

Gunk may have been holding the butterfly valve plate slightly open (?), and now after cleaning it's at the correct position causing a low base idle because the air bypass screw might have been screwed in previously to lower the idle, which might previously have been too high due to gunk holding the butterfly open a little (?).

The base idle may be too low for the IACV to adjust back up to spec idle, but I suspect only if the IACV is still blocked or partially blocked.

The idle may have been initially erratic because you'd changed the parameters affecting idle speed, and the ECU might have been 'learning' to set idle correctly. However I'm not sure if this would be the case or not as I'm not sure if this is one of the things that the ECU has to 'learn' rather than just adjusts through the IACV as any idle speed problem presents itself to the ECU.

Erratic idle may be associated with an air leak. Make sure the '8' shaped rubber IACV gasket is not leaking.

I then noticed this weird noise from the withing the hood...so hard to describe, it sounds like a low pitched electronic 'droning' noise from the air intake.
I took the air filter off and I can actually hear it coming from the throttle body (listening through the air intake pipe). If i disconnect the cable from the IACV that goes to the head the sound stops.
So i did an engine code check and its 14...which means IACV problem?!

The noise seems unusual, but it must be coming from the IACV if it ceases when you disconnect the IACV. The noise would be transferred from IACV though the IACV intake port (that begins just in front of the butterfly plate in the throttle body), so it would sound like it was coming from the throtle body.

It must be associated with air flowing through the IACV, which would be why it stops when the IACV is disconnected. If it was a noise being caused by a noisy solenoid (the IACV is operated by a smallish solenoid), then I'd expect to hear any noise coming directly from the IACV. If the IACV is making a noise I'd be suspicious of the IACV.

You'll be getting an IACV code simply because you disconnected the IACV, and at that moment (or up to a few minutes later) the ECU detected and logged a 'fault'. Try clearing the code and restart the motor with the IACV connected to see if you still get an IACV CEL. It may take a few minutes for the ECU to detect any IACV fault (or it may detect it quickly), so let it run for a while.

The ECU can only directly detect an electrical IACV problem, if the electrics are working then it can't directly 'know' if the IACV has an air flow problem.

I think i may have gotten the cleaner into the black Denso plug unit on the IACV and stuffed it up!

Maybe, but I doubt it. I think it's pretty well sealed.

I took it back out and re-cleaned it and checked it...no result.
Any suggestions guys? Might have to get a replacement? I'm in Australia...might be tough haha

Honda dealer or wrecker for an IACV valve, not tough at all (depending on price of course!). I'd reset the base idle speed before I went any further or blamed the IACV. The base idle will be stated on a sticker on the underside of the bonnet. Set base idle with the IACV disconnected or the diagnostic connector under the dash shorted with a wire.

[JohnD1079]

i dont think the dealer sells IACV or FITVs

[PittCB7grl]

Have you tried adjusting the idle screw on the upper portion of the throttle body? Later!


John D - the dealer can get you just about anything if your willing to pay for it.

[khemmo]

Hey John

Guys, major thanks for the advice hehe!

I left it overnight and seems the weird noise has stopped, though the idle is still low, car does not shudder anymore. I will try to adjust the idle but i'm not having luck unscrewing the plate off! Almost wrecked the screw threads.

Got worse throttle response down low now though! Feels 'spongey' accelerating
Any tips if adjusting the throttle cable screws (right definition?) will help?

Gunk may have been holding the butterfly valve plate slightly open (?), and now after cleaning it's at the correct position causing a low base idle because the air bypass screw might have been screwed in previously to lower the idle, which might previously have been too high due to gunk holding the butterfly open a little (?).

The base idle may be too low for the IACV to adjust back up to spec idle, but I suspect only if the IACV is still blocked or partially blocked.

The idle may have been initially erratic because you'd changed the parameters affecting idle speed, and the ECU might have been 'learning' to set idle correctly. However I'm not sure if this would be the case or not as I'm not sure if this is one of the things that the ECU has to 'learn' rather than just adjusts through the IACV as any idle speed problem presents itself to the ECU.

Erratic idle may be associated with an air leak. Make sure the '8' shaped rubber IACV gasket is not leaking.



The noise seems unusual, but it must be coming from the IACV if it ceases when you disconnect the IACV. The noise would be transferred from IACV though the IACV intake port (that begins just in front of the butterfly plate in the throttle body), so it would sound like it was coming from the throtle body.

It must be associated with air flowing through the IACV, which would be why it stops when the IACV is disconnected. If it was a noise being caused by a noisy solenoid (the IACV is operated by a smallish solenoid), then I'd expect to hear any noise coming directly from the IACV. If the IACV is making a noise I'd be suspicious of the IACV.

You'll be getting an IACV code simply because you disconnected the IACV, and at that moment (or up to a few minutes later) the ECU detected and logged a 'fault'. Try clearing the code and restart the motor with the IACV connected to see if you still get an IACV CEL. It may take a few minutes for the ECU to detect any IACV fault (or it may detect it quickly), so let it run for a while.

The ECU can only directly detect an electrical IACV problem, if the electrics are working then it can't directly 'know' if the IACV has an air flow problem.



Maybe, but I doubt it. I think it's pretty well sealed.



Honda dealer or wrecker for an IACV valve, not tough at all (depending on price of course!). I'd reset the base idle speed before I went any further or blamed the IACV. The base idle will be stated on a sticker on the underside of the bonnet. Set base idle with the IACV disconnected or the diagnostic connector under the dash shorted with a wire.

[92bently]

are u talking about the throttle cable itself??or the adjustment screw??

[johnl]

I left it overnight and seems the weird noise has stopped, though the idle is still low, car does not shudder anymore. I will try to adjust the idle but i'm not having luck unscrewing the plate off! Almost wrecked the screw threads.

What plate?

Got worse throttle response down low now though! Feels 'spongey' accelerating
Any tips if adjusting the throttle cable screws (right definition?) will help?

Do you mean the throttle stop screw? This screw is not an adjustment as such, it purpose is to hold the butterfly valve disc just ever so slightly open. If the butterfly disc completely closes against the bore ot the throttle body it can get stuck, especially when the throttle body cools down and contracts.

If you've been playing with this then you need to take the throttle body off and re-adjust the butterfly so that when you hold the throttle body up to the light you can see a very slight sliver of light around the circumference of the butterfly disc. It should only be very slightly open when it's 'shut'. Idle air flow is adjusted with the air bypass valve not the butterfly.

If you mean the cable itself then you need a small amount of slack with the throttle closed, but also to make sure than with the pedal fully depressed that the butterfly is open all the way.