I lifted the hood and listened carefull where the sound came from. I tried to pull the throttle cable a little. When the rpm went down, I heard the sound come out (the sound was "po.po.po.po.po.po"). I tried a few times and got the same sound. It came from around the air filter box and the air intake tube.
The idle is stable, and the engine still works fine (just near 100,000 miles). But the rattling sound seem to get more and more noticeable as the engine gets older. I'm kind of annoyed by it.
I've search the discussion threads, and found one or two posts in a similar problem was mentioned. But seems no definite answers have been found.
The sound once disappeard after my mechanic adjusted the TPS (throttle position sensor?) But the sound came back a few weeks later.
I'd like to know if anyone has any clues about this problem? Thanks a lot.
could be that your valves need to be adjusted or if it is more like a dull pop or thud it may be that your injectors, does it do it constantly or only for a few seconds?
The sound occurs when the rev drops to idle rev, lasting for only one or two seconds.
Another thing is, i don't think describing this sound as "rattling" is quite right, since nothing is getting loose and causes the noise. Some people say it's "tapping" noise, although nothing gets contacted.
What I can say for sure is the noise comes from the air intake part, and this may be a hint that there is something wrong with the engine, causing some abnormal air induction, I guess.
There's the blue ACV on the left side of the intake manifold (passenger side). Unhook its electrical connector while the motor is tapping/rattling/whatever and see if it goes away....
There's the blue ACV on the left side of the intake manifold (passenger side). Unhook its electrical connector while the motor is tapping/rattling/whatever and see if it goes away....
-Tim
Tim
I did as you said. I disconnected the ACV, and..amazingly, the weird air-induction sound disappeared. Could you tell me what the ACV is for? What may this suggest? Is there anything out of order?
Thanks.
Tim
I did as you said. I disconnected the ACV, and..amazingly, the weird air-induction sound disappeared. Could you tell me what the ACV is for? What may this suggest? Is there anything out of order?
Thanks.
The ACV is an idle control device. If you look at it, there's a rubber vac hose that goes below the intake manifold and connects to a metal pipe. There's another hose connected at the other end of the pipe which connects to the bottom of the intake resonator.
I forgot what I did to get it to flutter. If you look at the resonator (big heart looking contraption), then put your hand under it, there's a tube that connects to it. Make sure it's on there snug. The resonator should quiet the sound enough so that you DON'T hear ACV operating.
Btw, I'm not able to see the image, getting 403 (Forbidden).
The ACV is an idle control device. If you look at it, there's a rubber vac hose that goes below the intake manifold and connects to a metal pipe. There's another hose connected at the other end of the pipe which connects to the bottom of the intake resonator.
I forgot what I did to get it to flutter. If you look at the resonator (big heart looking contraption), then put your hand under it, there's a tube that connects to it. Make sure it's on there snug. The resonator should quiet the sound enough so that you DON'T hear ACV operating.
Btw, I'm not able to see the image, getting 403 (Forbidden).
-Tim
sorry I didn't double-check if the page is accessible.
Please try this: http://www.llaclub.info/viewtopic.php?t=3597 (It's a Chinese page. Just ignore the characters or codes that make no sense to you. There are three jpg files on that page. I'd like refer you to the second from the top.
Weird. There are a couple things labeled wrong on that picture. They've got the O2 sensor near where the water temp sensors are. The 4AFE doesn't have a Fuel-Pressure Up solenoid.
Weird. There are a couple things labeled wrong on that picture. They've got the O2 sensor near where the water temp sensors are. The 4AFE doesn't have a Fuel-Pressure Up solenoid.
-Tim
One of my friends reminded me, just a few minutes before I saw your reply, that the picture might be the one for 4AGE. What do you think of it?
I checked the ACV. The hoses at the both end of ACV and of the metal pipe you mentioned seem snug on where they're supposed to be.
I pulled the hose off the ACV, and I heared the loud sound of ACV operating.
I think the resonator still works well silencing the ACV when it operates. But I can still hear the damped sound occasionally.
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