photog

I've been having some harsh audible vibrations at idle for about 2k miles now. Since then, I've replaced all my mounts with OEM mounts, rebuilt my leaky PS pump with fresh seals, cleaned my EGR, ran seafoam through my fuel tank, and nothing has improved the audible vibrations I'm having at idle even with A/C off. After talking to a Parts guy at my local dealer, I was suggested to either A.) get a valve adjustment, or B.) check to make sure my spark plugs are still torqued. Apparantly they get swarms of 04-08 TLs into the service department with loose or ejected plugs. This didn't occur to me because I just replaced all of my plugs 30k miles ago, using a calibrated torque wrench, and double checked each one before installing the coils.

Turns out the middle rear plug was nearly 50% unscrewed, and the coil was hard to get out because it was covered in oil. Apparently this plug worked itself free sometime in the last 30k miles and allowed carbon and exhaust heat to leak past it's threads and dry out the o-ring gasket at the top of the valve cover, creating a slow leak. There doesn't seem to be any oil on the spark plug, but there is a ton of carbon buildup all over the plug and tube.

I'm due for a valve adjustment (114k miles), so I might as well replace all the o-ring gaskets when I do that.
After retightening the plug it seems like my vibrations are still just as bad. Do you guys think my coil might be shot from having oil buildup and extra heat exposed to it? I am going to try swapping the spark plug and seeing if that helps with the rough idle. I still have a loud valve tick coming from the rear cylinders, but was hoping that was just an indication of needing a valve adjustment

rockstar143

iTrader: (6)

Any CEL's? Damaged coil should kick a misfire.

photog

Unfortunately no CEL, just vibrations as if all of my brand new mounts are cracked

rockstar143

iTrader: (6)

Could it be that the vibrations are just MORE apparent because you were used to broken mounts absorbing a lot of the shock?

Won't valve adjustment also help with quieting and lessening vibration? I have that on the horizon myself.

J.

photog

I hope so, might try the adjustment this weekend. I can't see it really having that much of an effect on the vibrations but I suppose it's worth a shot since it's such a cheap DIY.
Does anyone know if a throttle position sensor would throw a code if it was giving a rough idle?

rockstar143

iTrader: (6)

I thought that would cause limp mode, not bad idle.

Just for kicks, why not move the dirty/hot coil pack to one of the front cylinders, just so see if you get a different vibration etc.

How are your tranny mounts?

Have you been doing squats? Maybe your glutes have gotten more firm and that's why it seems more obvious now? Just thinking out loud and outside the box!

photog

Ahah nah definitely lacking on the squats. I've never been sensitive to the usual honda AT vibrations but I'm hearing these vibrations through my dashboard (pulsating rattle) and feeling it in the pedal and steering wheel. night and day difference to what the car used to feel like at idle.

My upper tans mount is new, bottom one looks to be in good shape too. My subframe mounts looked okay as well but there isn't an easy way to tell how those are holding up.

nfnsquared

OP, did you use anti-seize when you replaced the plugs? What torque spec did you use?

photog

I used a microscopic dab of anti-seize , set the torque to 13ft lbs

rockstar143

iTrader: (6)

And you're feeling this just sitting there at idle?

paperboy42190

iTrader: (7)

broken mounts do not absorb any vibration. quite the contrary, a broken mount would send in tons of vibration into the cabin

paperboy42190

iTrader: (7)

did you neutralize your motor mounts when you installed them? if not, it will def cause slight vibrations.

photog

Yea at idle, used to be only with A/C on and turning the wheel slightly at a stop, eventually has gotten worse and happens in all conditions at a stop. even with A/C off, wheel turned straight, lights off, etc.

I neutralized all of the mounts at the same time after replacing them, then torqued down the bolts where they all connect onto the subframe.

rockstar143

iTrader: (6)

I was just thinking out loud...sorry, man. I do hope you find out what it is. Thanks for that George, that makes sense.

photog

Thanks man, I appreciate all the feedback

photog

After another hour under the car/hood i've found that the vibrating noise I am hearing is the rear motor mount bracket bouncing against the metal bump stop that bolts down on top of the mount. This mount was just replaced and is in perfect condition.
Seems like something is bogging down the engine enough to shake the motor hard at low RPMs.

Does anyone know if a worn out drive belt tensioner (the 2 pullies on a spring loaded bracket) would bog down the engine and cause a hard vibration?
Maybe a clogged catalytic converter?
No CEL otherwise I'd know where to start

rockstar143

iTrader: (6)

Still don't think it's that coil pack being bad? Move it to the front bank of cylinders and see if the engine vibrates differently.

I had to replace the entire tensioner assembly (chose to) to get rid of a LOUD bearing failure noise, but I don't think it could put enough pressure on to affect the motor vibrations.

photog

I swapped it to the front and didn't notice anything change with the vibrations, also put a new spark plug in but that didn't help either.
That makes sense regarding the tensioner, I figured I'd be hearing a bearing failure if it was toast, but what about the spring loaded bracket becoming worn? The whole unit seems to wobble around but I think that's to be expected with the belt spinning