Random Rough idle/shifter shake/seat vibration

[AngryBeavers]

So my car (3000 miles, base GT) has this really bad, random vibration more noticeable at idle. It doesn't do it all the time but when it does it causes a bad left to right shake most noticeable in the seat. When it happens you can also see the shifter shake a good bit. I looked under the hood and saw a real steady wobble in the bolt on the front of the engine connected to the harmonic balancer/crankshaft.

I took it to the dealer and had a tech look at it before I admitted it for service (I know coyotes can be finicky with this kind of stuff.) and pointed the loose screw out to him. He told me it was normal and that the nut just wasn't machined through perfectly center so it looks loose. He did agree that the idle felt rough and I should leave it over night though.

I pick the car up the next day because the dealer cannot replicate the issue. I'm like wtf?? the tech in front of me admitted it was strange?? It didn't flash any codes and they didn't notice anything on the test drive.

I still notice the vibration and the shifter shake (I can get a video up later). It does not seem to matter with cold start or if sitting at a light after driving. It definitely isn't a consistent issue, it comes and goes. Another thing I've noticed is my voltage fluctuates sometimes when driving. It ususally sits around 14.4 but I've noticed it moving down to 12 and back up to 14 in mid drive. I'm thinking it has to be that balancer messing up the pulley/alternator.

What do you guys think? Timing chain? Loose screw? Should I take it back to the dealer, take it to a different dealer or is it just coyote things? I'm worried that the balancer being off will cause damage to engine/transmission components.

Sponsored

 

[Nemesys]

Hey Angrybeavers,

I may be able to shed some insight on this for you. That wobbling harmonic balancer I had checked out by a dealer ( I had the same concern ), and it turned out to be the washer was off center. But looking at it head on it looks like its wobbling completely.

The idle in my opinion on these cars seems way too low. 850 or so seems like it would be much smoother. Want to know how I know? Next time on a cold start crank your car up, youll notice three idle down points. First is from about 1000 then kicks down to about 850 ish, car feels great, no weirdness, the final idle point where you hear the exhaust noise drop considerably is when you feel the vibration.

Generally speaking my 3valve 4.6 had a little shake at idle, its a big motor ;) They all will tend to do that, and kinda adds to the "muscle" feel of the car. However, I think a higher idle would benefit everyone.

My voltage also fluctuates like you mention, and I had it checked out twice at a dealer and Ive heard a few different reasons for it, but its something Im monitoring.



Here is the video of my pulley/bolt , dealer checked it and said it was fine.

[ame]

 

[Asharus]

ive seen my voltage drop to the 12s before, but the following morning it was up to 14.x. i've only seen it dip to 12/13 2 or 3 times. im not sure what that's about either, but i'm not really concerned about it. as long as the car starts strong in the morning in this cold winter, i think im good.

 

[bvdawg13]

As for the voltage, my car does this too. The first time I saw it in the 12's and I was on the highway. Most commonly its in the upper 13's, lower 14's. At first I was paranoid my car would end up not starting after the the time I saw it in the 12's but everything has been good. I did end up reading that these are 12V batterys so when the voltage is low like that, it means they are charged. When the voltage is 14.xx it means the car is charging. It does make sense.

My shifter vibrates as well, I thought it's just part of having a 5.0?

 

[Asharus]

that makes sense. the last time i saw it in the 12s was during a really really long commute

 

[AngryBeavers]

Thanks for the replies everyone. Now that you mention it, I did notice the voltage does go into the 12s on long commutes. As for the vibration, I get the whole "muscle car" feel as I like some vibration in the shifter/car. What concerns me is the randomness of it. The shifter/car will just violently jerk side-to-side sometimes at the light, other times can't feel anything. I've noticed also that when you push in the clutch when its vibrating, it gets worse (although I think this is due to the slight RPM increase).

I think what you said is right Nemesys. Probably something off with the idle in the computer that ford can't figure out yet. Hoping that when it gets warmer the sometimes clunky transmission/rough idle issues pan out. At 3000 miles of some WOT, some long commutes, and normal city driving I'd say this stuff is beyond engine break-in issues. I just want to make sure everything is squared away before I throw on new exhaust and get denied a warranty claim.

 

[Nemesys]

I think what you said is right Nemesys. Probably something off with the idle in the computer that ford can't figure out yet. Hoping that when it gets warmer the sometimes clunky transmission/rough idle issues pan out. At 3000 miles of some WOT, some long commutes, and normal city driving I'd say this stuff is beyond engine break-in issues. I just want to make sure everything is squared away before I throw on new exhaust and get denied a warranty claim.

Out of curiosity, as I do experience the same little weirdness as you do with the vibration. Do you mind on your next cold start letting it idle down for about 5-10 minutes.

The thing Ive noticed is the drive-train on this car is pretty damn quiet at about 750-800 until it idles down completely at 650, then the noises tend to start and the vibration/lumpy feeling begins. You can even hear occasionally itll try to rev up too.

See if you can snag a vid of the idle down from the middle 800 point to the final 650 point. I wonder if theres a huge difference in the way the noise sounds on yours. For example, this is what I hear at that idle point.

At 58 seconds the noises start. It slowly quiets down after it warms up completely though or if its been driven.

[ame]

 

[bvdawg13]

Bumping up. Just realized tonight when remapping my car with the X4, that I could set the idle myself. I set it at 750 rpms. I will see how it feels next couple days

 

[AngryBeavers]

Bumping up. Just realized tonight when remapping my car with the X4, that I could set the idle myself. I set it at 750 rpms. I will see how it feels next couple days

How did you manage this?

 

[jamesfd21]

Mine does the same thing, i find it stop when i push the clutch in. Noticed it when i was at the bank next to the window.

 

[Nemesys]

Mine does the same thing, i find it stop when i push the clutch in. Noticed it when i was at the bank next to the window.

Notice too when you clutch in the rpms slightly go up. The idle on our cars is stupid low. On my read out it reads 600 flat a lot of times and even 590.

 

[FordService]

What do you guys think? Timing chain? Loose screw? Should I take it back to the dealer, take it to a different dealer or is it just coyote things? I'm worried that the balancer being off will cause damage to engine/transmission components.

Mine does the same thing, i find it stop when i push the clutch in. Noticed it when i was at the bank next to the window.

Have you contacted your dealer yet to address the issue, jamesfd21? Send me your 'Stang's mileage, and I'll see how I can further assist.

Also, AngryBeavers, are you still experiencing the issue? I'm going to look more into this.

Jeff :ford:

 

[jamesfd21]

I agree the idle is too low for the car, i think it should be at about 800 or so. I have an appointment to Brig my car this Friday, im pretty sure they will tell me there is nothing wrong with it so they dont have to spend any money, happen the last time on my 2014, had a rough idle, and nothing was done, they said we have it in our notes so if something breaks we will know you tried to resolve it.

 

[Nemesys]

I agree the idle is too low for the car, i think it should be at about 800 or so.

Thats what Ive got mine set to.

 

[jamesfd21]

Thats what Ive got mine set to.

Im kind of holding off to tune mine, my luck as soon as i tune it, something expensive will break.

Sponsored