Created a thread about this a while back and no one seemed to know what it was. Anyways, after changing my fuel filter one day, about 3 weeks later my idle would drop from say 800 too 300. During and after this drop there is a loud humming noise, you can even hear it outside with the hood shut. I've cleaned the IACV, checked for vacuum leaks, nothing. I'm stumped and I'm in college so no time for tear down.

It has not affected drivability so I just left it go and waited for something else to break. It's now 7 months later and it's still happening. However, I was wondering that if the fuel filter bolt, the one that feeds the fuel with the hole in it, wasn't on correctly and a bit of the hole was covered making a it run a bit lean, could that be the problem??

I wish I had a sound clip, but no video-camera. It's really bothering me..... Any ideas would be great.

 

is this all the time?
if that were the case it wouldn't get fuel when you rev it also...

any CELs?
could be that your AICV went out on you but is still present enough to make the ECU think it's ok. (I've seen it more than once)

what kind of car/engine/setup/etc?
done a tune up? (plugs, wires, cap, rotor)
have you checked you ignition timing?

 

Well lets see

1. It only happens at idle. No gas, gas actually makes it stop.
2. It is getting fuel because it doesn't die
3. Stock d16y8 except I/E/H
4. Change oil, filter, religously every 2500-3000, plugs every 6000
5. It has had not wires around 25000 miles ago.
6. Haven't checked the timing however...
7. No Cel's the entire 7 months this has been happening

AICV? same as IACV? I have cleaned the IACV, but to no avail.

I'm stumped. Anybody?

 

when something similiar happened to me my distributor died shortly after... but that might not be the case in this situation...

 

I did replace the short ram with the stock for the hell of it and made it quieter, but it was still a little noticeable. The noise is definitely coming from the Intake out, or atleast the intake is amplifying it.

 

is your TB clean? I would say your tb might be open but your idle is lower? hmm

 

hmmm, is right. this is freakin annoying.

I thought it might be the TB. But i cleaned it as well and it still did it. I thought it might have some residue build up (90000 miles) but guess not.

I just went and removed the PCV line that leads to the intake and plugged the intake hole with my finger. The noise got quieter but didn't go away. I have no idea what this means but someone else might or it might mean nothing

 

I have a Y8 too with 100k, did a cap, rotor, wires, plugs, and fuel filter about 15k ago. That's when I noticed the exact problem you have. Tried cleaning the tb and adjusting the idle, didn't solve it. I did the timing belt 5k ago and that didn't change anything either. It doesn't make the noise til it's warm, just still bugs me every day.

 

Ha, glad i'm not alone with this one. That sounds exactly like what happens. I'm leaning more towards a possible vacuum leak or one of the air control valves. If you not, ya got me. Maybe one of Ht's brightest can chime in......

 

vacuum leak would cause the idle to go up not down.
do you smell fuel when this happens?
ECU - OBD2 or OBD1 chipped?

 

OBD2 and I have noticed a very, very, very (it's slow if didn't get it) drip from the bottom of the fuel filter. Like the filter is on tight enough or the threads are jacked.....

 

with OBD2 even if the CEL is not on you may have a code. Try taking it to a parts store that will scan for codes for free.

the fuel smell would be out the exhaust if it's what would cause this problem.

 

It was hooked up to scanner in September for inspection. NO codes..........

Any other ideas?? I'm all out, about to call it quits.

 

Checked for vacum leaks, exhuast smells normal, no dripping from fuel filter...???

 

I would check the new fuel filter like you mentioned since it is leaking anyway. Replace the copper washers and get it sealed up.

I have a dropping idle problem and I have a noise coming from inside my distributor. I think its a bearing or the shaft going out. I can feel the problem when the car is running and I put my hand on the dizzy. Havent replaced it yet...

Where is your noise coming from? I find noises by touching the blade of a long screwdriver to suspect spots on the engine and placing my ear against the handle. Has a stethescope effect. Noises will be very apparent

 

The noise is coming from the intake, loudest right by the tb. I recently noticed a very slight bounce in the rpms at warm idle.

 

aaaaah!!! I can help! I had this problem on a d15!

it turned out to be my FITV (fast idle thermo valve). try cleaning/replacing that.

heres what to do to confirm this. Go out to the car and take off the intake so you can see inside the TB. there will be a hole in the side of the TB on the firewall side. see if it gets louder or quiter when you place your finger over it.

^^ yes i know those holes lead to the IACV, but i replace the iacv in my car with no result, same issue. pondered my thoughts and thought about what else it could be, change the FITV and it stopped and ran perfect

 

exactly what i was going to suggest...good thinking 93eg2james..

 

Thanks man, I'll have to check this out when I back from school (college). I've cleaned the IACV once already. I'll try this. It's not effecting anything, but sometimes the rpm drop to 400, 300 when it's warmed up, just annoying....

 

turn off the A/C

LOL.

 

Finally threw a cel light for the IACV, it came on when I was a stop and when I began to drive it felt like the e-brake was on and I really had to rev it and drop the clutch just to get it moving. I was only up the street from my house so I just drove it home. I got a new oem IACV reset the ecu and it wes fine until exactly 500 miles later and the light came back on, wtf?

 

possibly the tps needs to be recalibrated? if you hook up a scan tool (to the obd port) it will tell you all at once if anything is off. tps beinf offf can throw a idle air control system code.