Vibration on acceleration

dano · Jan 21, 2008

My car for the past few weeks has been vibrating on acceleration. I went and had the wheel balanced checked out and they were out of balance and one rim is bent, But, the vibrationonly happens after 3500K and after about 45 mph and only on acceleration. If I either down shift or maintain the rpm if goes away, If I push it it starts to vibrate. I think it might be something engine or drivetrain related, it seems to rev fine, but vibrate. Could a bent wheel cause this? I can cruise at 60 pmh and no vibration, if I drop a gear and rev it from 3500 to 7000 (more noticeable between 4000 and 5000 rmps) it vibrates. It doesn't do it in first gear, kind of does in second and gets really bad in third and havn't gone past fourth besauce I'm going faster than I need to be safe. I checked my plugs, regapped them to .051", they looked ok a little brownish white and have just replaced the 02 with a Motorcraft o2 sensor. No check engines and no noises and I have a pretty good ear for odd sounds on cars. Could I have a bad or loose motor mount? Flywheel and or clutch going out? Any input would be appriciated.

Thanks,

Dan

SVTF4243 · Jan 21, 2008

Long shot but check your cat mount

1svt4u2c · Jan 21, 2008

I'm going to start by taking a stab in the dark and saying I don't think it's the tranny. And as for a bent wheel, usually thats something that would cause the car to vibrate all the time. However, if you have a buddy near you with a focus, swap wheel's for a quick drive around the neighborhood. But again, I don't think it's the wheel's.

As stated above I'm going to have to second that. Check your rear motor mount (the dog bone mount). While you're at it, might as well check your other two mounts. Hope this helps!

-Matt

dano · Jan 21, 2008

Thanks guys, on checking the motor mount, i know there should be some play if I rock if from to back, but how does the engine act (not running) if I rock it by hand and have a bad mount. I'll also check the cat mount, the shield is allready gone, so I'm sure the mount will be next.

Thanks,

Dan

Segovia · Jan 22, 2008

I actually have the exact same problem.

http://forums.focaljet.com/svt-headquarters/566384-shaking-problem.html

I haven't figured anything out yet either. I can say for sure in my case its not wheels, as I swapped out my rims for winter tires and the problem is still there. As of right now all I can guess is a motor mount. You should definitely let me know if you figure something out.

fritotec · Jan 22, 2008

check the drivers side half shaft, the cvs joint might be bad.

McSVT · Jan 22, 2008

I had a bad CV joint and I had a slight vibration while acceleration. Dealership replaced it upder waranty.

dano · Jan 22, 2008

Well, I did go check the top motor mounts. By standing in front of the car I pushed on the out sides of the valve cover evenly and the drivers side seemed to have more give than the passengers side, but it would only move like 1/4" drivers nono passenger. Since I rotated my tires the whole cars shakes now where it used to just feel like the front end. Funny thing is, it vibrates more in 3rd gear than any other.

bmylez · Jan 22, 2008

Hmm...perhaps some of your tires are out-of-round? It's not always the wheels that cause vibration. Just a thought since it seems wheel/tire related. Do the tires make a lot of noise?

Cnelson12 · Jan 22, 2008

it seems to be related only to the engine speed as he says he can "cruise at 60 with no vibration" so its unlikely that it has anything to do with the wheels, cv joints or anything after the output shaft

does it vibrate if you just sit in neutral and rev the engine?

dano · Jan 22, 2008

Cnelson12 said:
does it vibrate if you just sit in neutral and rev the engine?

Havn't tried that yet. I did a WOT test today from 1st to 4th and no vibration. But if I go part throttle in 3rd and try to accelerate moderately fast after 3500 rpms but not WOT, it will vibrate through 5500-6000 rpms and kinda smooth out, and if I shift into 4th its smooth. The funny thing is most of this started after I removed my 65mm tb and went back to stock and also replaced the o2 with a Bosch. I have since replaced the Bosch with a OEM Ford unit. Maybe I need to clean my MAF?

SVTF4243 · Jan 22, 2008

Is your DSI Opening properly? That rpm zone is when it should open

carlingskie · Jan 22, 2008

is there any squeeking/vibrating noise when you're parked?:what:

dano · Jan 22, 2008

Oddly, no noises either parked or driving. I did get a noise yesterday, a squeek like a wheel bearing in the rear as I rolled and it wasn't the brakes, it was below freezing at the time and stopped after a few 100 feet of driving.

The DSI should switch around 5K or so. The vibration is present with either the stock or VMP tune. The funny thing is if I granny it around under 3.5K you'd never know it was there. It's really odd. I'll do some more dirving on my way home and see if I can narrow cause and effect. The one thing I havn't done is get on the freeway and see what it does over 70.

dano · Jan 22, 2008

Segovia said:
I actually have the exact same problem.

http://forums.focaljet.com/svt-headquarters/566384-shaking-problem.html

I haven't figured anything out yet either. I can say for sure in my case its not wheels, as I swapped out my rims for winter tires and the problem is still there. As of right now all I can guess is a motor mount. You should definitely let me know if you figure something out.

I just read your post. The only thing I can relate is that is has been below freezing hear. But the problem still happened above freezing to 50 deg F. Have you looked into anything, seems like a few people have this problem.

Segovia · Jan 23, 2008

I still definitely had the problem before it was winter here. I haven't tried any fixes yet though.

It's pretty much the same thing for me though it sounds like. If I stay below 4k or so, there seems to be absolutely no shaking. Third gear and up is where it's most noticeable. It's pretty frustrating to say the least.

dano · Jan 23, 2008

First off, I'd like to thank all who have aided in my "issue". If we all hold hands, we'll get thru this

So I cleaned the MAF and that didn't help. Did some cause and effect on my way home and here is what I found in my 21.5 mile drive home from work;

-It only vibrates at light and moderate throttle
-It is most noticeable in 3rd gear above 3500 rpms
-you can feel it in 2nd and 4th but not as much
-I can do it in 5th and 6th but i'm bogging the engine at that point (2000 rpms)
-It will vibrate ever so slightly if I hold the rpms arounf 3700
-By vibrate I mean I can feel it in the car/floor board but not in the steering wheel, pedals or shifter.
-There are no noises at all. All I can hea is the air rushing over my car and the ries on the road
-easy around town driving, can't feel a thing unless I go past 3500 rpms.
-I can cruise at 70 mph and it as smooth as an SVT can get, even with a bent rim.

I'm stumped.

I will note that I had a warped rotor on the drivers front for about 18 months. The warp was not real severe, it was out about .010". Could this have cause damage to the suspension or motor mount on that side? When I checked the motor mounts, that side (drivers) moved the most, the passenger didin't move at all.

dano · Jan 23, 2008

Segovia, some food for thought, I checked out this thread and sounds somewhat simular to our problems.

http://forums.focaljet.com/svt-head...t-headquarters/487001-remember-vibration-problem-i-had.html?highlight=vibration

focusben · Jan 23, 2008

I'm getting my axle seal replaced (driver's side) this Friday since it was leaking/trickling some tranny fluid. I had the vibration on and off again this past couple of months. I'm thinking that's all it is and not the CV joint or shaft.

dano · Jan 23, 2008

Well, I just left work early to look this over during the day. I got the front of the car off the ground and looked the cv and axle shaft support bearing over and all looks good. I even had my wife run the car in first gear while I looked under it ( I do not suggest you do this unless you have experiance) and found nothing. No noises, wobbles or anything.

What I did find was that I'm missing one rib on my accesory belt. It was the second one in from the passenger side, completly smashed or ground flat. I contacted my Dealer as I recalled at one point they mentioned replaceing the belt (under warrenty) because it was worn odd for some reason. So it will go in Saturday for inspection.

Vibration on acceleration

dano

SVTF4243

1svt4u2c

dano

Segovia

fritotec

McSVT

dano

bmylez

Cnelson12

dano

SVTF4243

carlingskie

dano

dano

Segovia

dano

dano

focusben

dano

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