Lightning Rodder banner
1 - 20 of 27 Posts

·
Registered
Joined
·
671 Posts
Discussion Starter · #1 ·
I'm going to try an explain this one so I hope someone has experienced this too. This doesn't happen every time but it happens a couple times a week. Keep in mind this loud buffeting sound that lasts for a couple of seconds happens a couple of different ways:

1. I start the truck and begin to drive and if I press the brake pedal at any point within a minute of driving the sound will appear.

2. I start the truck put it in gear while pressing the brake pedal and sound will appear.

Seems to have something to do with pressing the brake pedal which draws extra vacuum creating the fog horn buffeting sound for a couple seconds. The weird thing is it does not do this every time. Could it be a bad brake booster? The brakes feel fine. Any ideas?
 

·
.030, XR heads, [email protected]
Joined
·
12,831 Posts
maybe you've got a cracked hose that runs from the brake booster to the steel hose by rear of blower?:smt102
 

·
Registered
Joined
·
671 Posts
Discussion Starter · #3 ·
I recently ran some seafoam through that brake booster hose and I did not see a leak. I will check the hose again just in case.

I'm not sure if this would cause the problem but I replaced the old IAC with an ebay cheapy and not too long after I started experiencing that sound. Is it possible that the IAC is defective?
 

·
Premium Member
Joined
·
1,427 Posts
I do not know what you mean by buffeting sound but I have a sound also when doing exactly what you are saying. I have just been ignoring it and everything has been acting normal so I don't think its anything to worry about.
 

·
Registered
Joined
·
598 Posts
Could be the check valve where the hose connects to the booster. If that is bad it will draw extra vacumn when hitting the brakes. If you didn't get all the stuff out of the hose before you hooked it back up to the check valve it may have ruined the valve.
 

·
Registered
Joined
·
671 Posts
Discussion Starter · #6 ·
Could be the check valve where the hose connects to the booster. If that is bad it will draw extra vacumn when hitting the brakes. If you didn't get all the stuff out of the hose before you hooked it back up to the check valve it may have ruined the valve.
The sound started before I used the seafoam.
 

·
Registered
Joined
·
671 Posts
Discussion Starter · #8 ·
I do not know what you mean by buffeting sound but I have a sound also when doing exactly what you are saying. I have just been ignoring it and everything has been acting normal so I don't think its anything to worry about.
I try to ignore it too but when it happens I can't get it out of my mind for a couple of days on WTF is causing it. It is hard to describe the sound. I know it can be heard outside of the truck cause I can hear it inside the cab when it happens. Sounds more like how a motor boat sounds when taking off in water slowly. I always get a mental picture of air bouncing around in the intake air tube every time it happens. Do you still have the stock IAC on the truck?
 

·
Oil Field Trash
Joined
·
2,643 Posts
it sounds like the IAC is sticking.

My HD did something very similar, and I couldn't figure it out for the life of me. It only happened at low rpms, with no throttle, or just a tad. Did it most often, right when I lightly stepped on the brake.

Turned out to be the IAC.
 

·
Dude
Joined
·
2,368 Posts
My first response would be the IAC as well I lived with mine that way for 9 mos thought it would be expensive. It wasnt 54$
Good luck!
 

·
Registered
Joined
·
671 Posts
Discussion Starter · #14 ·
it sounds like the IAC is sticking.

My HD did something very similar, and I couldn't figure it out for the life of me. It only happened at low rpms, with no throttle, or just a tad. Did it most often, right when I lightly stepped on the brake.

Turned out to be the IAC.
I ordered a new delphi IAC that goes on a 04L since the ones for the 00L has a connector that goes straight back. Your issue sounds exactly like mine.
 

·
Innovator of the Bombassani exhaust
Joined
·
2,428 Posts
IAC for sure.... Had a SVT Contour and those cars were notorious for this sound. It was called moosing to the Contour community. Also be prepared for disappointment..... I had to go through two OEM IACs before I got one to work right. Looks as if they are a crap shoot out of the box.

Later
 

·
Registered
Joined
·
671 Posts
Discussion Starter · #17 ·
Hmm, I wonder if mine is the IAC as well. If it was the IAC wouldn't there be idling problems like the truck not wanting to idle or idling high? Mine idles just fine.
Not necessarily because it could just be sticking intermittently or could be the wrong IAC for the vehicle which it is causing it not properly maintain idle when a load is placed on the engine.

definition:

The Idle Air Control Valve (IACV), or stepper motor, allows the electronic control unit (ECU) to regulate the airflow to the engine independently of the driver's throttle input.

When the engine is idling ECU uses this control (in parallel with ignition timing modulation) to compensate for varying loads that the engine must overcome to maintain the desired idle speed (i.e. friction, electrical load, A/C compressor load etc)

The IACV is also used to control airflow during load changes between positive and negative torque to provide a throttle damping function to improve the drive-ability characteristics of the vehicle.
 

·
Registered
Joined
·
671 Posts
Discussion Starter · #18 ·
IAC for sure.... Had a SVT Contour and those cars were notorious for this sound. It was called moosing to the Contour community. Also be prepared for disappointment..... I had to go through two OEM IACs before I got one to work right. Looks as if they are a crap shoot out of the box.

Later
Yup, I'm on my third one.
 

·
Registered
Joined
·
671 Posts
Discussion Starter · #19 ·
The loud sound happened again today after work when I got to the house. I stopped jumped out and walked down the drive way to grab the mail and jumped back in, threw it in drive while barely touching the brakes and wammo their was the noise.
 

·
7th Fetzer valve, yeah...
Joined
·
2,144 Posts
These noise threads are tough without audio. Try capturing this sound with somebody else pushing the brake pedal?
 
1 - 20 of 27 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top