Strange hum coming out of my SHO...

[Orkin]

I've recently noticed a strange hum coming from my car at idle. Tonight I investigated further to see if I could see where it's coming from. After searching around the car, I noticed it was most pronounced around the MAF. I lifted the intake assembly from the filter box, and the sound was definately coming from inside. I then removed the assembly from the TB, and the sound was even louder coming out of there. It sounds almost like the test tone a TV station plays along with the colored rectangle screen, but lower. (sorry, I'm not sure how to explain it) It goes away above 1k RPM.

There's also a knocking sound (almost a chirp) that's bothering me that comes from about the center of the intake manifold. Could this be my car's why of asking for a valve lash adjustment?

While I'm at it, I'm also getting a CEL, with codes for both O2 sensors on the KOEO, and for just the LH sensor in the KOER test. What should I check for this?

I'm at 114k, so it's almost time for a tune-up, and I'm not sure if it has ever had a proper one (bought at 111k with no service records).

Thanks for any suggestions!

 

[Machspeed]

I dunno bout the hum, you sure its just not the sound of the engine. Does it sound like the knocking is coming fromt he bottom of the engine? Could be a valve out of alignment, could be a loose spark plug, possibly a rod bearing. I would replace your 02s, you can get em at autozone which is where i got mine. Sounds like your car needs some lovin.

 

[NinjaMike]

This is normal intake resonance. The sound is normal. Some of the cars do it, some of them don't. All of mine have and it is quite annoying at idle.

As far as the ticking/ knocking/ chirping, those types of sounds are next to immpossible to diagnose over the internet, but if it is indeed coming from the center of the intake as you had suggested, I would think valve lash or chain tensioners.

 

[NotSoSlowSHO]

yes, the hum is normal. When I first bought my SHO it did it. I found that cleaning the throttle body, and rotating the intake hose a bit reduced the noise a bit. But then I took the intake horn and outer airbox out... so the noise is back

As for the chirping noise...

Ill add noisy injectors to the list of possibles.

But if the car has no documented 60k, then you should start planning for one. wink

 

[V6&V8SHO]

Change out your Idle Air Bypass. That fixed my hum. Seems removing the silencer agravates it.

 

[BeatDaSHO]

Yo man. The sound is definately normal. It is air being sucked into the throttle body. My bro's SHO is really loud and you can't even hear mine at all. Weird. As for the knock sound, it is most likely a worn cam lobe. I have one worn cam lobe that damages the shim. It makes the sound you have described. The only thing you can do is buy a new cam and replace it.

Greg

 

[sdpatt]

Not all SHOs have the resonance that creates the sound. Mine does not sing this song, but I have heard it on several others. It has to do with the sound pulses resonating within the intake tract.

 

[V6&V8SHO]

My car did the same thing, then I had midwest sho replace the IAB and it doesnt make the noise anymore.

 

[Orkin]

Thanks for the quick responses everyone. I guess I just hadn't noticed the hum before (only had it a few months).

I'm planning to do the 60k tune-up soon, I've been reading up on it, and I'm about ready to start ordering parts.

As for the O2 sensor codes, I forgot to specify what kind of codes they were. I'm getting 136 on the KOER, and 172 and 176 on the KOEO (memory). The CEL only comes on after being run for awhile, especially after I've been doing some passing on the highway. I'm also experiencing an intermittent loss in power at the low end.

 

[Groo]

The sound is NOT normal. It means your IAB motor is fuxored. You have to either clean it out (if it's an MTX) or purchse a new one (if it's an ATX).

That hum gets super annoying in traffic, I'm glad it's gone. Unforunately, now my fuel pump hums loudly...

 

[Rockledge]

Interesting that the SHO does this too....I have read a number of posts from people with 4.0L Rangers who have described the same kind of noise emanating from their engines...turns out the culprit on the Ranger is the IAC, as well.

 

[ohioshodude]

my sho has/had a hum. i always thought it was the tranny. i'll have to recheck and see if it is really the intake.

 

[SHOtimer]

Mine used to hum, replaced the IAB and no more noise.
Doug

 

[NinjaMike]

Groo:
The sound is NOT normal. It means your IAB motor is fuxored. You have to either clean it out (if it's an MTX) or purchse a new one (if it's an ATX).

That hum gets super annoying in traffic, I'm glad it's gone. Unforunately, now my fuel pump hums loudly...

The sound does not indicate a failure of the Idle air bypass valve, although replacing the valve often removes the noise. Perfectly functioning IAB valves will sometimes make this noise too.

 

[NotSoSlowSHO]

not to mention that there is no AIB motor...

 

[ES_8CH_OH]

Digging up an old thread...

I am experiencing the annoying hum when I take my foot off the gas when cruising. It is especially noticable when sitting still at idle. Replacing the idle bypass valve is the answer. Correct?

 

[twr]

I've only ever heard that noise coming from ATX cars. I traced it back to the AIB on one car, not sure if the owner ever did anything about it. But replacing the AIB should fix it.

 

[ES_8CH_OH]

Rock Auto lists the part as a Idle Air Control Valve, IAC valve (pronounced eye-ack). I have bought this part for my Mustang a few years ago. I see it mentioned above as AIC, IAC, and IAB. I just wanted to properly identify this part so others can find it easily. Rock Auto wants $57 for it. I could not find it on www.FastPartsNetwork.com (formerly www.FordPartsNetwork.com).

 

[Tommy's SHO]

Hummmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm

Yup, my ATX does the loud humming too. It's funny to see the reaction of the toll booth people when you drive up and they hear that sound.
Once, when I was crossing over the border to Canada the border patrol asked me to unlatch the hood so they can check if "everythings ok".

That was a few years ago, and yes, I'm still hummmmmmming away.

P.S.- It only does it when engine is hot.

 

[1993MTXSHO]

yeah my F-150 does it and boy is it annoying i wonder if its a ford thing.