Strange noise from throttle body

[rwmorrisonjr]

I'm getting a strange noise from the throttle body on my 5.4. When I put it under very light load, like in a drive-thru, I'll get a brief "metallic" or raspy sound for 1-3 seconds, like its starving for air or gas, then it goes away. It won't make the noise when I'm already moving or starting from a dead stop, but when I'm idling forward and just touch the gas. I've cleaned the throttle body once, but might need to do it again. It doesn't effect milage or power, but don't want it to grow into something bigger.

 

[pitdexion]

Exhaust heat shield rattling perhaps.

 

[rwmorrisonjr]

Exhaust heat shield rattling perhaps.

That’s one idea I had, just haven’t had the time to get under the truck and check.

 

[coolzzy]

Could be VCT solenoid too, most noticeable at light throttle in drive or reverse. Some noise is normal. Lots of noise is bad.

 

[rwmorrisonjr]

Could be VCT solenoid too, most noticeable at light throttle in drive or reverse. Some noise is normal. Lots of noise is bad.

Thanks. Haven’t experienced any of the symptoms (CEL, rough idle, etc.), but I’ll run it down after I check the heat shields. With 143k miles on the truck, this is the first engine noise I’ve experienced.

 

[rwmorrisonjr]

Crawled under the truck this weekend and couldn't find any loose heat shields, so I'm ruling those out. It only seems to make the noise under a sudden light throttle, like tapping it in a drive-thru, or when at a constant RPM in a high gear and the transmission won't downshift. It also seems to be coming from the front of the car. Could it be an idler pulley or similar going bad? Going to test those when I get back from my trip Thursday and its a bit cooler out.

 

[rwmorrisonjr]

Ok, I was able to get a video recording of the noise. Here's when it happens:

• In gear under light throttle
• Around 900-950 RPM
• Goes away when not in gear or above/below 900-950 RPM

Thoughts are appreciated!

 

[Cyclone]

Flywheel touching starter gear?

 

[rwmorrisonjr]

Flywheel touching starter gear?

Doesn’t make the noise when not in gear. I shifted into neutral during the video and the noise stopped, even at 900-950 rpm.

 

[rwmorrisonjr]

Deleted as repeat post.

 

[JExpedition07]

VCT solenoid rattle, some odd noise is normal. If it’s loud they may need replacement.

 

[rwmorrisonjr]

VCT solenoid rattle, some odd noise is normal. If it’s loud they may need replacement.

EDIT: I disconnected the VCT solenoids and tested the engine again, and no rattling noise. I tested it with in gear and the noise returned. I reconnected the VCT solenoids and revved the engine without load and no rattle.

As I said, it only makes the noise when in gear and under load. I tested for the noise again and it sounds like its coming from the transmission/transfer case area. I don't think its the starter/Bendix since its intermittent and only at that particular rpm range.

Here's a better recording closer to the ground. Will try to get my wife to help tomorrow so I can get a better recording.

 

[rwmorrisonjr]

Found my rattle! It was a broken heat shield clamp on the Y pipe under the transmission. $2 hose clamp later and its all silent again!View media item 6904

 

[762mm]

Awesome, thanks for sharing! Everyone loves a happy ending!