Acceleration Vibration

[stkelly]

I recently replace my front differential due to bad bearings. Now the truck drives great when coasting and there is no noise. However, when accelerating there is a vibration that you can feel in the steering wheel, gas pedal and even the floor boards a little. As soon as I stop accelerating the vibration goes away completely. You can feel it mostly around the 2K - 3K rpm range, outside of that the vibration subsides. This vibration issue existed on the previous front diff.

I've searched and seen that others have reported the same symptoms. Unfortunately, none of the treads I read had a solution to the problem.

Does anyone have any ideas as to what could be causing this vibration? I've heard u-joints, but most said that the vibration should exist even when coasting.

I was thinking of disconnecting my front drive shaft and driving around to see if the vibration stops. But I wasn't sure if it was 100% safe to do that in the AWD Moutaineer's. Some threads I've read said driving without the drive shaft could ruin the transfer case. Is this true?

Thanks in advance!

08 Mercury Mountaineer AWD.

 

[Flag Gibby]

If it is not the tires, then it is definitely from the u joints or CV joints. In my experience, you don't feel u joint vibrations in the steering so I don't think it is the driveshaft. To answer your question, if you completely remove the front driveline and pull the transfer case fuse (4x4 fuse) you should be fine for low speed testing. However, when you do that I believe you will lose fluid from the transfer case and front differential.

 

[stkelly]

Thanks for the input. I'll try and drive around without the front driveshaft and report back what I find.

Just for testing purposes, I decided to rev the engine in park. I noticed that the engine shakes the truck in the ~1500 RPM range and smooths out completely above ~1,800 RPM. Is this normal for the 4.6L 3V? If not, any ideas of what could cause this vibration? I wonder if this is contributing to the problem.

Thanks!

 

[Flag Gibby]

A stumble at 1.5-1.8K sounds like the ignition system has problems. A lot of the V8 owners here regularly have 1 coil go bad and they have to track it down. It is typically the ones closest to the firewall because they get water trapped in the spark plug area of the manifold (typically #8 cylinder I believe).

 

[stkelly]

Thanks again. I found a ford tech bulletin that said to unplug the transfer case to diagnose acceleration vibrations. I gave it a try and there was no difference in the vibration. I could definitely tell the truck was sending the power to the rear wheels. They were quite easy to break loose!

I'll purchase a new COP and rotate it around each cylinder to see if I can stop the vibration at 1500 rpm.

Thanks again!

 

[stkelly]

Yeah, I had water trapped in cylinder 4 (drivers side firewall). I blew out all the water and installed 8 new COPs. I installed the yellow accel ones. There was no difference in the shaking between 1,500-1,800 rpm. I was going to try replacing the spark plugs next. Is there anything else in the ignition system that can cause this shaking/vibration? Should the engine be perfectly smooth from 1,500-1,800? I'm wondering if some of the vibration is normal. The truck has 63K miles.


Thanks again.

 

[Flag Gibby]

You could try cleaning the mass air flow sensor and that might help some, but if you have more than 60K miles on the plugs then it doesn't hurt to change the plugs.

 

[stkelly]

Could the harmonic balancer cause a vibration in this range? I looked at all the items in the serpentine belt and nothing even really looked like a balancer. The shaking at 1,500 is enough to make items in the passenger seat shake. Like straps to a purse and whatnot.

I already ordered some plugs, can't wait to tackle the sticky plugs. I'll probably video tape that as well. (I have a diff replacement video I haven't finished processing yet).

Thanks!

 

[Flag Gibby]

I don't know what frequency/RPM the balancer is specifically for. However, a few individuals here have reported shaking issues that have gone away with a spark plug change so I would just focus on the spark plug change and then go from there if the problem doesn't subside.

 

[stkelly]

Just for anyone following: As I was waiting for my plugs to come in I decided to run a can of BG 44K through. It was for two reason, first to see if it would help at all with the acceleration or revving vibration. And second, to help break up some of the carbon so I can hopefully pull my plugs more easily.

The BG 44K didn't make any difference at all in either vibration. So maybe save your $25 if your thinking this my address any engine vibrations.

I'll be changing my plugs this weekend so I'll see if it helps me go 8 for 8 on the plugs. I know It'll be hard to say if the BG 44K definitely helped, but hey anything that may make it easier I'm all for.

Thanks

 

[jcat9]

it's not throwing any codes at all?

Have you investigated the possibility of motor and/or trans mounts?

 

[stkelly]

I did have a misfire code when there was water in plug well 4. Cleaned the water out and new COPs no more codes.

I looked at the mounts and they looked fine. Solid piece of rubber. Are there any hidden signs they're broken?

Thanks

 

[stkelly]

So after changing the spark plugs, COP and fuel filter I still have the revving vibration right around 1,500 - 1,800 rpm. I'm beginning to think this may be normal. My sister has an 02 Explorer with the 2V v8 and it seems to have a similar vibration at those rpms. If anyone happens to have a 3V V8 could they let me know if their engine is 100% smooth in the 1,500-1,800 rpm range?

Also, the acceleration vibration hasn't really changed either. I haven't been able to 100% verify due to a flat on the drivers side front. I have the spare on, but I don't want to risk damaging the front differential I just replaced with a mismatched front tire. Tire Rack is shipping in a shaved tire as I type.

Thanks!

 

[paulyjsob]

I've had this exact issue since I bought my 07 AWD V8 Mountaineer. Mechanics have tried to track it down with no success and have driven other AWD model with the same behavior.. I've learned to live with it and have accepted that its normal for this truck.

 

[Gargoyle]

I had a similar problem with an old Landcruiser. It was smooth until I replaced the rear drive shaft universal joints - the vibration was terrible. I replaced the U-joints with OEM and the vibration sunsided a lot.
Stupidly I read the manual to late. It explicitly said that the drive shaft components MUST be re-assembled exactly as they came apart - everything must be lined up. Eventually, after having to replace a flange, the vibration occurred only during deceleration, if I turned the flange around 180 degrees the vibration occurred only when accelerating. So to make it short, I had to purchase a complete new assembled drive shaft - no vibration. Somehow the compnents of the shaft are matched and balanced during manufacture. This may have been your problem. So far I have had no driveline problems with my '08 explorer v8.

 

[Back_Yard_Handyman]

Little late too the party but I have a very simple solution for your gas pedal vibration! Your engine cover!! I noticed whenever I had mine off on my (2002 MERCURY MOUNTAINEER PREMIER 4.6 2VALVE) my gas pedal and steering wheel wouldn't vibrate, but as soon as I had it back on it vibrated both of them at low speed and RPMs. I think it's touching the throttle body cable just enough to vibrate it. Also I think you're cruise control cable runs right underneath the cover as well if I'm not mistaken. This is only true for DRIVE BY CABLE not drive by wire. Take the engine cover off and go for a spin might be surprised!!

 

[smittyCO]

hi! new here! have had a vibration when accelerating between 45-55mph in my 2013 exploder after changing the rear brakes and rotors :/ I have balanced the tires, then got new tires....took it to a garage near me and they cannot figure it out either. I'm at a loss. but so tired of the shaking (I fear the vehicle will shake apart!). This shaking didn't show up until after changing the rear brakes. any suggestions are appreciated! thank you! =]

 

[Gargoyle]

I recently replace my front differential due to bad bearings. Now the truck drives great when coasting and there is no noise. However, when accelerating there is a vibration that you can feel in the steering wheel, gas pedal and even the floor boards a little. As soon as I stop accelerating the vibration goes away completely. You can feel it mostly around the 2K - 3K rpm range, outside of that the vibration subsides. This vibration issue existed on the previous front diff.

I've searched and seen that others have reported the same symptoms. Unfortunately, none of the treads I read had a solution to the problem.

Does anyone have any ideas as to what could be causing this vibration? I've heard u-joints, but most said that the vibration should exist even when coasting.

I was thinking of disconnecting my front drive shaft and driving around to see if the vibration stops. But I wasn't sure if it was 100% safe to do that in the AWD Moutaineer's. Some threads I've read said driving without the drive shaft could ruin the transfer case. Is this true?

Thanks in advance!

08 Mercury Mountaineer AWD.

You may have changed something in the drive shaft - I had the exact same vibration experience on rear drive shaft when replacing the flange 180 degrees off, and on the front driveshaft when replacing the flange.

 

[Gargoyle]

I recently replace my front differential due to bad bearings. Now the truck drives great when coasting and there is no noise. However, when accelerating there is a vibration that you can feel in the steering wheel, gas pedal and even the floor boards a little. As soon as I stop accelerating the vibration goes away completely. You can feel it mostly around the 2K - 3K rpm range, outside of that the vibration subsides. This vibration issue existed on the previous front diff.

I've searched and seen that others have reported the same symptoms. Unfortunately, none of the treads I read had a solution to the problem.

Does anyone have any ideas as to what could be causing this vibration? I've heard u-joints, but most said that the vibration should exist even when coasting.

I was thinking of disconnecting my front drive shaft and driving around to see if the vibration stops. But I wasn't sure if it was 100% safe to do that in the AWD Moutaineer's. Some threads I've read said driving without the drive shaft could ruin the transfer case. Is this true?

Thanks in advance!

08 Mercury Mountaineer AWD.

You may have changed something in the drive shaft - I had the exact same vibration experience on rear drive shaft when replacing the flange 180 degrees off, and on the front driveshaft when replacing the flange.