Strange Noise (Revving) with Acceleration - Intermittent

[scud]

I have a feeling this has been discussed, but since the symptoms are based on self interpretation, I was stumped at how to begin even searching the threads for keywords.

Well, this has happened mostly at low speed. I will begin to accelerate, listening to the motor's normal revving sound (pitch and loudness)...then that sound will intensify. It isn't the normal increased rev with heavy throttle, I've floored it many times and never got even close to the pitch and loudness I will sometimes get. It's a very significant in increase when it happens. I would say it is at least an increase of 50%.

When this happens, the truck will still accelerate and the sound will stay consistent through the rpm range. If I accelerate all the way to 5th, the noise goes away. Similarly, if it starts happening, I can get on and off the gas a couple times and then it goes away.

Some recent things I've done were put in a drop-in k&n style air filter...and cut down the inlet tube inside the airbox to create more room inside for air. Also, when I installing my fog lights I disconnected the battery.

I'm wondering if anyone has experienced this...maybe it's just a matter of me temporarily screwing up the computer because of disconnecting the battery and now I need to have it flashed?? I wish I had a video to post.

Thanks in advance for any insight. I appreciate it!

scud

 

[UKPONY]

There is a relearn procedure for the ECU after the battery has been disconnected for a while (20 minutes+ if I recall correctly). The process is in the handbook & likely can be googled.

 

[scud]

There is a relearn procedure for the ECU after the battery has been disconnected for a while (20 minutes+ if I recall correctly). The process is in the handbook & likely can be googled.

thanks for the reply. I'm hoping it's just that too...I will take a look at the relearn process and see if I need to make adjustments.

 

[calahan#2211]

Is this a bit of a howling kind of sound? Has it happened at other than full to hard acceleration? It could be the filter and inlet restriction removal. You are most likely hearing the intake track air flow. The little horn object you removed is used to help quiet down the air flow noise... Doesn't like it is anything to worry about.

 

[scud]

Is this a bit of a howling kind of sound? Has it happened at other than full to hard acceleration? It could be the filter and inlet restriction removal. You are most likely hearing the intake track air flow. The little horn object you removed is used to help quiet down the air flow noise... Doesn't like it is anything to worry about.

Not a howling sound...I've heard increased intake noise and howling before with different intake systems I've had on previous vehicles. This just sounds like it's actual engine noise. You hit the gas and you can hear the engine...well, imagine that that same noise all of the sudden increases b 50% and goes to a slightly higher pitch. That's what I was experiencing. It would actually happening a lower and light acceleration...rather than all of the sudden start at high or hard acceleration. But, it hasn't happened for at least two days now...so I'm hopeful that it's because I disconnected the battery. I'll report back if it comes back in any way. Thanks for the help!

 

[scud]

well, no luck yet. it doesn't appear that it is related to disconnecting the battery, as I've been driving the truck for many days and it's still doing it.

sometimes, when it starts acting up, it is slow to return to idle as well and will rev a little on its own.

after modifying the airbox a little to let more air in, I'm wondering if it is too much air now...and maybe the idle-air-control is acting up?? maybe a MAF thing?

it's interesting though, because no codes are being thrown...no CEL

 

[scud]

potential update. I got it to do it while parked in the driveway...popped the hood and realized it was the radiator fan increasing in speed while trying to cool things off. I didn't realize the fan was belt-driven and an e-fan...so it never occurred to me there would be variable fan speeds that may be different than the belt speed. then I realized that obviously there were cooling issues...so I checked my coolant level and it was a little too low. without the coolant there to cool off the engine, it was basically starting to overheat I think and then kicking on the e-fan feature at random times...I added coolant and hopefully that will be the problem solver...

 

[jadez03]

potential update. I got it to do it while parked in the driveway...popped the hood and realized it was the radiator fan increasing in speed while trying to cool things off. I didn't realize the fan was belt-driven and an e-fan...so it never occurred to me there would be variable fan speeds that may be different than the belt speed. then I realized that obviously there were cooling issues...so I checked my coolant level and it was a little too low. without the coolant there to cool off the engine, it was basically starting to overheat I think and then kicking on the e-fan feature at random times...I added coolant and hopefully that will be the problem solver...

Keep us updated, I have this same type of noise and I've yet to determine where it's coming from...my coolant levels are topped off though, and mine doesn't seem to do it at idle.

 

[scud]

jadez03 - it's been almost 2 weeks now and it hasn't done it once. I know for sure it was the efan cycling off/on an inappropriate times due to low (no) coolant. make sure you check all your fluids after you buy a used sport trac off the lot haha. I hope you find what's going on with yours. do you know if it's your radiator fan? or are you still searching for the noise?

 

[bigmiketino]

I have a 2002 and when its gets cold the high pitch noise comes back when I start up in the morning, I dont know where its coming from maybe alternator. I just dont want to be stranded, has anyone corrected this cold weather high pitch noise.....

 

[jadez03]

jadez03 - it's been almost 2 weeks now and it hasn't done it once. I know for sure it was the efan cycling off/on an inappropriate times due to low (no) coolant. make sure you check all your fluids after you buy a used sport trac off the lot haha. I hope you find what's going on with yours. do you know if it's your radiator fan? or are you still searching for the noise?

Still searching - it's probably the fan glitching out but I haven't heard it much these last few weeks. I wonder why it's so intermittent. Maybe my mind is playing tricks on me?

 

[Mart1n]

Still searching - it's probably the fan glitching out but I haven't heard it much these last few weeks. I wonder why it's so intermittent. Maybe my mind is playing tricks on me?

Did you ever figure it out (intermittent fan noise?) I have the seame issue

 

[Tike]

have you tried to remove your belt and start it up see if the noise is there?
dont keep the engine on to long as it will heat up.

 

[Mart1n]

What I did is unplug the wire to the clutch and it stopped.

 

[Tike]

What I did is unplug the wire to the clutch and it stopped.

u sir have a bad clutch fan.

free tool rental from autoparts store. and a new clutch fan from rockauto fixed it for me.
***i recommend draining your engine coolant and doing a flush while ur swapping in the new fan.

if you dont. you'll still need to siphon off coolant from the rad in order to disconnect the upper rad hose and not make a mess... i learned that the hard way.

my engine temp was steady too. when the clutch fan is 'locked / stuck' it wont damange anything. its just making the engine work a slight bit more all the time and is supper loud. so youre loosing mpg. i was loosing about 2-1.5mpg.

 

[Mart1n]

How are you so sure it's the clutch fan?

 

[Tike]

you could check the current through the wires. theoretically if there is no current (on signal) and the fans locked its a bad fan. if you're getting that current then i'd check elsewhere

like i said, you'll loose mpg. and you'll sound like a semi.

 

[Mart1n]

you could check the current through the wires. theoretically if there is no current (on signal) and the fans locked its a bad fan. if you're getting that current then i'd check elsewhere

like i said, you'll loose mpg. and you'll sound like a semi.

Oh I sound like a semi allright. I also get the feeling I lose significant power. Like I wrote, the fan stops if i unplug the wires, so the clutch is getting a signal to engage. Do you know the voltage / amp readings I should get and between which wires (I think there are at least three wires going to the clutch)?

 

[Theresa S.]

I have a feeling this has been discussed, but since the symptoms are based on self interpretation, I was stumped at how to begin even searching the threads for keywords.

Well, this has happened mostly at low speed. I will begin to accelerate, listening to the motor's normal revving sound (pitch and loudness)...then that sound will intensify. It isn't the normal increased rev with heavy throttle, I've floored it many times and never got even close to the pitch and loudness I will sometimes get. It's a very significant in increase when it happens. I would say it is at least an increase of 50%.

When this happens, the truck will still accelerate and the sound will stay consistent through the rpm range. If I accelerate all the way to 5th, the noise goes away. Similarly, if it starts happening, I can get on and off the gas a couple times and then it goes away.

Some recent things I've done were put in a drop-in k&n style air filter...and cut down the inlet tube inside the airbox to create more room inside for air. Also, when I installing my fog lights I disconnected the battery.

I'm wondering if anyone has experienced this...maybe it's just a matter of me temporarily screwing up the computer because of disconnecting the battery and now I need to have it flashed?? I wish I had a video to post.

Thanks in advance for any insight. I appreciate it!

scud

I'm having the same problem. Have you found a diagnosis or fix yet?

 

[jdemaris]

Well, this has happened mostly at low speed. I will begin to accelerate, listening to the motor's normal revving sound (pitch and loudness)...then that sound will intensify. It isn't the normal increased rev with heavy throttle,

scud

I have a 2008 Sport Trac 4WD. Has 134,000 miles on it. I bought it last year and do not have a complete service history on it. I also note I worked as a truck and auto mechanic for most of my adult life. I only mention that to indicate I have some mechanical experience. I pretty much stopped working as a mechanic in the early 90s and now only repair my own vehicles. I do not keep up with auto technology unless forced to when working on one of my own vehicles. That all said, this 2008 Sport Trac is the newest vehicle I own. I bought it as a trade-in at a local Ford dealer. Something I would normally never do. I was getting ready to drive 150 miles to look at a V8 Sport Trac for sale privately. Then I saw this one parked locally in the back lot at a Ford dealership. I figured I'd test drive it just to find out if I even like the V8 Sport Trac (I had never driven one before). Long story short, I loved it and bought the one at the Ford dealership, as-is. The Ford people told me although they had done no work to it, it was completely checked over. It ran good, and I got it as a sort of impulsive buy. Since then, seems every time I take a trip some new problem shows up. It is obvious either the people at the dealership lied, or their definition of "checking everything" is a lot different then mine. I had to put in a new radiator, new front brake calipers, new struts in back along with some suspension bushings because the back wheels were crooked when any weight was in the back. How does this relate to your problem? Maybe it does and maybe it does not. I drive in the woods a lot at low speeds on logging trails. Recently, at very low speeds I started getting a noise. Not an engine noise. It is a rolling vehicle noise, so whenever the wheels are turning, the noise would come and go. I sounded rotational and like something rubbing now and then. This went on for over a month and at first, on the highway at 80 MPH, it ran fine and quiet. On my last trip to the Michigan Upper Peninsula, the noise in the woods at low speed got worse and more consistent. When back on the highway, at 75-80 MPH, the same noise started to come and go. Sometimes it would be a repetition of the noise cycling 3-4 times, go away, and then come back. I could find no particular pattern to it. Does it going straight down the highway, just cruising. No turning, no braking, no acceleration. I got home yesterday and put the Sport Trac up in the air. I found out the center driveshaft support is complete broken (the rubber mounting). So the driveshaft can just flop around. It took me an entire day to get the driveshaft off which was kind of a surprise. I have never come across a driveshaft flange so stuck where the front of the driveshaft bolts to the flange on the transfercase. After spending near an entire day of trying to carefully separate it and NOT beat it to death with a large hammer? I finally had to fabricate a sort of separator, in place, and used 6 bolts to push it apart. This was POOR engineering by Ford. They could of had holes drilled and tapped for pusher bolts in the transfercase flange but did not bother. I got the driveshaft out but so far, have not found a way to get the two halves of the driveshaft apart. In the center by the support that failed, is a CV joint with a retainer that is pressed on and crimped. I undid the crimp, got the retainer off, but have not yet found a way to make it come apart. I also found out that the rear universal joint is bad and is staked in. Oddly, even though Ford staked it in, the snap-ring grooves are there and not used. So I assume I can cut out the bad universal joint and replace with a conventional one held in by snap-rings on the outside of the caps. At this point, I am thinking this was the cause of the noise. I found a brand new complete driveshaft for $290 and am waiting for it to show up from UPS. I hope it fits and hopes it fixes the noise problem. I am also going to fix the original driveshaft for a spare IF I can find a way to do it. The new replacement driveshaft is a little different then the original. The new one I have coming only has one CV joint where it bolts to the transfercase. The center and rear joints are conventional U-joints. If it fits, I doubt it matters. I am amazed that Ford would make a driveshaft with a center-support that is considered non-replaceable.