2007 Honda Accord - Vibration at Idle

[The Critic]

My GF has a 2007 Accord four cylinder, automatic, with about 103k miles.

The issue is that the car vibrates noticeably at idle when in gear (D or R), and the vibration is even worse when the a/c is on. I have found that a cold engine does exacerbates the issue, and the vibration is worse in reverse than in drive.

I have driven two different Accord four-cylinders of the same generation (one was a 03, another was 04) and both had significantly more miles -- but both had zero vibration under the same condition.

So far, I have done/verified the following:

- Did a "power brake" test - found no significant rips/tears at the front hydraulic mount or at the rear mount. The front mount does have some slight weather-related cracking, but there are no obvious rips or tears. The rear mount is quite difficult to fully inspect with the bracket still on, but from what I can tell, it looks like it is in good shape. I'm not sure how I would verify a "collapsed" mount.

- Inspected the side mount and found no issues.

- Used a block of wood and a floor jack to lift the rear of the transmission while the car is in gear, and this resulted in only a slight reduction in the vibration.

- Tried to test the function of the dual-mode front mount by increasing the engine rpm to 1,000 - found noticeably more cabin vibration at 1,000 rpm than at 800....so I think the dual-mode function is working properly.

- Performed a valve clearance adjustment, slight improvement in idle quality but no significant changes.

- Performed a complete transmission service using Genuine Honda ATF-DW1, no change.

My understanding is that the front and rear mounts are the load-bearing mounts on this vehicle. Based on what I've seen, the front mount sees the most stress when in D (the engine tilts upward) while the rear mount sees more stress in R (engine tilts downward).

I have done a lot of searching on the forums but have not found any conclusive answers. There is a TSB out for the 03-04 models to replace the front mount (and inspect the rear) as a solution for correcting excessive vibration at idle, but the 07 in question already has the updated mount listed.

I would like to get some additional ideas/opinions before I drop $215 on new front and rear mounts - it feels like I'm just guessing at this point.

Thanks in advance.

 

[Merkava_4]

When you say "vibration," you're not referring to a rough idle correct ?

And the vibration is directly associated with the rotation of the engine correct ?

 

[krismoriah72]

I bought my mother a 2008 and it was doing the same thing when we bought it with around 40K miles. I think they changed the throttle body in 07 vs previous generations...anyways.. I had her switch to top tier shell in our area and also dump in a bottle of techron every other fillup and it has gone away.

Try a fillup of 89 octane or higher with top tier and techron or similar and do an italian tuneup then report back.

 

[Trav]

Does this have the electronic mounts? The rear is the most common and you will not see any rips or tears in it.
Look at the engine where it meets the mount, if there is a gap then its okay but its common to find it laying on the mount and that's what causes what you describe.
Be thankful this isnt a V6 the mounts are over $1200 a set not inc labor and it can be a bugger of a job.

 

[eljefino]

Electronic throttle? Clean that. Maybe the idle is off by 50 RPM and causing a resonance. Also try a bottle of injector cleaner.

 

[BAJA_05]

Motor mounts & how about last time spark plug replacement was done?

 

[Nick1994]

Sounds like motor mounts to me. Whatever you do, don't use aftermarket motor mounts. 9/10 they are junk.

 

[The Critic]

Originally Posted By: Trav
Does this have the electronic mounts? The rear is the most common and you will not see any rips or tears in it.
Look at the engine where it meets the mount, if there is a gap then its okay but its common to find it laying on the mount and that's what causes what you describe.
Be thankful this isnt a V6 the mounts are over $1200 a set not inc labor and it can be a bugger of a job.

Trav - you're probably thinking about the V6 and the ones with the VCM where the expensive rear mount often fails. This one doesn't have a vacuum operated rear mount. Only the front one is vacuum operated and is also hydraulic.

Originally Posted By: eljefino
Electronic throttle? Clean that. Maybe the idle is off by 50 RPM and causing a resonance. Also try a bottle of injector cleaner.

Idle looks like it is within specs. I've tried injector cleaner with no change. The valve adjustment has made the most noticeable improvement so far. I ain't touching the throttle body - have had too many bad experiences with cleaning those DBW units.

 

[Trav]

[quoteThe Critic]Trav - you're probably thinking about the V6 and the ones with the VCM where the expensive rear mount often fails. This one doesn't have a vacuum operated rear mount. Only the front one is vacuum operated and is also hydraulic. [/quote]

Critic, some of the V6 VCM engines are electronic/hydraulic only no vacuum, the rear is $650 retail cheapest online is about $425 and a PITA to do.
Is the one you have electronic with a single bolt mounting tab on top?

 

[Merkava_4]

Take the accessory drive belt off and see if the vibration goes away.

 

[mclasser]

Originally Posted By: eljefino
Electronic throttle? Clean that.

Hopefully Honda electronic TBs aren't as sensitive to cleaning and finicky as Nissan TBs are.

 

[Vikas]

Is this a misfire?

 

[lubricatosaurus]

Originally Posted By: Vikas
Is this a misfire?
Nope, OBDII "check engine light" is very good at detecting misfires.

 

[lubricatosaurus]

I like the accessory belt suggestion, yet very doubtful of that. Should be obvious the alternator is shaking too much anyway.

Does sound like engine mounts. Maybe gave out in twist (torque).

I don't understand the intake cleaning suggestions, as the OP has already said it idles at the right RPM steady.

 

[Hokiefyd]

Does the idle change at all with a slight increase in engine speed. My '08 CR-V always had what I considered to be too rough of an idle, but if I crowded the throttle JUST SLIGHTLY, to raise the engine rpm up 50-100 rpm, it immediately turned glass smooth, and was glass smooth in park and at all other engine speeds under load.

I attributed it to an aggressively low idle speed for emissions/economy and never did anything about it before I sold it.

 

[sxg6]

This probably isn't the problem but I will throw it out there anyways..

Automatic Subaru's do this with aftermarket cv axles installed. If the car has an aftermarket cv axle, and if the issue goes away when shifted into neutral, I would consider that as a possibility.

 

[The Critic]

Originally Posted By: Trav
Originally Posted By: The Critic
Trav - you're probably thinking about the V6 and the ones with the VCM where the expensive rear mount often fails. This one doesn't have a vacuum operated rear mount. Only the front one is vacuum operated and is also hydraulic.


Critic, some of the V6 VCM engines are electronic/hydraulic only no vacuum, the rear is $650 retail cheapest online is about $425 and a PITA to do.
Is the one you have electronic with a single bolt mounting tab on top?


This particular rear mount has a single bolt mounting tab, but is not electronic. This is the mount in question:

http://www.ebay.com/itm/Genuine-OEM-Hond...Q8Q&vxp=mtr

I had some time this evening and removed the rear mount's u-shaped safety bracket, but did not find any tears at all. I think the scenario I'm facing is that one or more of the mounts are slightly collapsed, but it is difficult to know which ones (or to what degree) unless I compare them side-by-side. At this point, I think I'm pretty much stuck with having to throw parts at the problem.

But on an unrelated note, I found out this evening that the a/c compressor is low on refrigerant. Not sure how this affects this story, but I'll report back after my a/c guy does his thing tomorrow...

Originally Posted By: Hokiefyd
Does the idle change at all with a slight increase in engine speed. My '08 CR-V always had what I considered to be too rough of an idle, but if I crowded the throttle JUST SLIGHTLY, to raise the engine rpm up 50-100 rpm, it immediately turned glass smooth, and was glass smooth in park and at all other engine speeds under load.

I attributed it to an aggressively low idle speed for emissions/economy and never did anything about it before I sold it.


It changes a bit. I've worked on a 08 CRV before I know the sensation that you are describing, and this one is rougher than the CRV.

Originally Posted By: sxg6
This probably isn't the problem but I will throw it out there anyways..

Automatic Subaru's do this with aftermarket cv axles installed. If the car has an aftermarket cv axle, and if the issue goes away when shifted into neutral, I would consider that as a possibility.


Good guess - but no, this car still has the original cv axles (thankfully). The vibration is less in P or N, but is not gone.

 

[Merkava_4]

I must've clicked the invisible ink button before clicking the submit button.

 

[RD400]

I was going to suggest a valve job, but you've got that covered.

Besides the mounts, check out the main crank pulley. Honda calls it a harmonic balancer. It's a two piece unit and the isolating rubber will deteriorate and may start to separate, causing the outer drive belt part to vibrate. If it's bad, you can see it wobbling at idle.

 

[t1snwrbrdr12]

did you check your timing when adjusting valves? mine at 200k runs smooth as new, but it did vibrate at idle when the timing was off due to a stretching chain. stretched chains sound very common on these apparently. I never had a check engine light until it got as far off time as about 3 teeth, and never thought to check timing due to it being a chain driving timing system. thought that'd be a lifetime system as opposed to needing service like a belt.

I've also found broken trans mounts (lower, along the subframe) which appear fine unless you have someone power brake them. just sitting I never knew anything was wrong with them, couldn't even see the slightest tear in them.

and as you already know the front motor mounts are prone to failure, but you usually see hydraulic fluid leaking from them if and when they fail, at least in my limited experience.