Engine idle vibration -- How much is too much?

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CraigLloyd
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Engine idle vibration -- How much is too much?

Postby CraigLloyd » Tue Apr 24, 2018 10:23 am

I have a base 2007 Vibe and it idles perfectly steady at 700 RPMs. However, there's a little bit of vibration, but I'm not sure if it's a problem or just normal with these engines.

Basically, it's a calm vibration that isn't too crazy or anything. Mostly just feels like a massager if you had it on a very low setting, and it's prominent in the steering wheel and by my feet. When I turn on the AC (thus, upping the idle to around 850 RPMs), most of the vibration goes away. I'm just curious if this is a normal vibration or something that needs looked at. My honkin' 4.8L Silverado from the same year definitely doesn't vibrate this much at idle.

I recently cleaned the MAF sensor and throttle body, but I haven't noticed a huge difference in regard to the vibration.

ehoff121
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Location: Conn.

Re: Engine idle vibration -- How much is too much?

Postby ehoff121 » Thu Apr 26, 2018 6:41 am

On one level, this is subjective- some are okay with what you are describing.

The real question is, "what are the causes of 'excess' vibration at idle?"

A few things could be involved- others will add to the list...

[*]Vacuum leak - typically at intake manifold gasket, but any rubber hose or gasket on the intake side of engine is possible
[*]Idle Air Control Valve (IACV) could be dirty and/or have a bad gasket
[*]Mass Airflow Sensor (MAF) could be dirty [which you already cleaned]
[*]Air filter could be dirty/clogged
2005 Pontiac Vibe AWD - Platinum

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vibrologist
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Re: Engine idle vibration -- How much is too much?

Postby vibrologist » Thu Apr 26, 2018 7:34 am

Chiming in here:

All in-line 4 cylinders are prone to vibration. Engineering deals with it in a variety of ways.
Engine mount bushings: Soft ones will reduce vibration at idle but will allow the engine to tilt at take off and sudden power demand etc. Hard ones will cause vibration at idle but handle the torque inputs better. Our Vibes have hard ones. My wife's '10 Ford Focus has fairly soft ones and and one of them is liquid filled and wears out relatively quickly.
"Smart" engine mounts: they have a magnetically reactive liquid in them that can instantly make the mount hard to deal with torque and go soft when idling. Some Acura's have them.
Balance shafts are used in larger I-4 engines and probably the best way of handling the inherent vibration.

H-4 engines (air cooled Beetles and Subaru) have less vibrations than I-4 but are more expensive to manufacture.
6 cylinder and 8 cylinder in just about any configuration are much better balanced. If you want it silky smooth get a V12......

If your engine is in proper tune the odds are it's vibrating normally. Something to get used to.
I would include the spark plugs into things to check.
Vibrologist
'05 Vibe

"It is important to know the difference between 'accurate' and 'precise' even if you are neither!"

http://forums.genvibe.com/phpBB3/viewtopic.php?f=30&t=43476

jolt
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Re: Engine idle vibration -- How much is too much?

Postby jolt » Thu Apr 26, 2018 10:44 am

Bad or weak motor mounts will let the engine vibrate more then when it was new. You may want to check your motor mounts.

ihaveavibe
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Re: Engine idle vibration -- How much is too much?

Postby ihaveavibe » Fri Apr 27, 2018 5:01 am

I also have vibration at idle and it's starting to get annoying, so thread is very timely. Unfortunately, I have more questions for you guys and no answers:

How can you detect/diagnose the vacuum leak mentioned above?
Where is the IACV and same question, how can you diagnose it?

Is there any way to diagnose the condition of the motor mounts without removing them?
I am basically aware of three mounts, but some places I see references to a transmission mount. Where is this, and is this different from one of the three motor mounts?

Vibrologist mentions a balance shaft in I-4 engines. Does 1zzfe have that? I'm guessing not.

Lastly, could it be the harmonic balancer? Or would that cause vibrations also at higher RPM, i.e. not just at idle?

Thanks!

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vibrologist
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Re: Engine idle vibration -- How much is too much?

Postby vibrologist » Fri Apr 27, 2018 2:29 pm

ihaveavibe wrote:I also have vibration at idle and it's starting to get annoying, so thread is very timely. Unfortunately, I have more questions for you guys and no answers:

How can you detect/diagnose the vacuum leak mentioned above?

There are different methods. Most common is to use a carb cleaner and spray it at suspected areas while the engine idles. If the engine reacts to the spray you found the vacuum leak. You can also use a length of a garden hose, hold one end to your ear and put the other at suspect parts along the intake. You may be able to hear a hissing sound.

Where is the IACV and same question, how can you diagnose it?
Somewhere at the throttle body, I believe

Is there any way to diagnose the condition of the motor mounts without removing them?

Visual inspection: Are there cracks? Put the gear in neutral and have someone stepping on the accelerator. Watch for excessive tilting of the engine
I am basically aware of three mounts, but some places I see references to a transmission mount. Where is this, and is this different from one of the three motor mounts?
See this thread: viewtopic.php?f=12&t=38461

Vibrologist mentions a balance shaft in I-4 engines. Does 1zzfe have that? I'm guessing not.
Your guess is correct.

Lastly, could it be the harmonic balancer? Or would that cause vibrations also at higher RPM, i.e. not just at idle?
I don't know

Thanks!
Vibrologist
'05 Vibe

"It is important to know the difference between 'accurate' and 'precise' even if you are neither!"

http://forums.genvibe.com/phpBB3/viewtopic.php?f=30&t=43476

jolt
Posts: 554
Joined: Sun Mar 02, 2014 2:07 am

Re: Engine idle vibration -- How much is too much?

Postby jolt » Fri Apr 27, 2018 9:58 pm

Finding vacuum leaks use carb or throttle body clean. Spray area and if engine RPM's change, you have a vacuum leak at that location. Be sure to spray around the intake manifold and all hoses. This includes the power brake vacuum line and the vacuum lines running back to the gas tank under the car.

IACV is part of the throttle body. In the upper right hand corner of this page is a box that says "Search", use it. ;) You will find posts about cleaning the IACV, and if I remember right, there are pictures too. This has more to do with idle speed then anything else.

Motor mounts, as vibrologist said, look for cracks in the rubber. Compare pictures of new mounts to the ones you have. Pictures can be found at http://www.rockauto.com of most any part. The rubber portion of the mounts that are round in shape on the out side, when new, will have the inside hole centered in the rubber. If the inside hole is not centered in the rubber, it has deformed over time. Watch for motor movement when under load as vibrologist suggested. There will always be some movement as that is what the mounts are for but there should not be a lot. You can watch the mounts and see how much they compress under load. If the rubber compresses a lot replace the mount. Also use the "Search" on this board about motor mounts because I have seen posts here in the past about this topic.

This motor does not have balance shafts, which really do not balance anything. Balance shafts are a counter balance of the forces from the pistons and crankshaft movement used on line motors or single cylinder engines. They can help smooth out an engine in some RPM ranges but also add more moving parts that can wear out and take more power from the engine to turn the shaft or shafts.

No harmonic balancer either. Harmonic balancers are typically used to dampen torsional vibrations with in the crankshaft. In most 4 cylinder engines there is not enough crankshaft length or journals where harmonics become a problem for the crankshaft, so a balancer for it is not needed.

ihaveavibe
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Re: Engine idle vibration -- How much is too much?

Postby ihaveavibe » Thu May 03, 2018 11:05 am

Thanks for the info. Will try the carb cleaner test. Regarding the mounts (there have been quite a few of these threads of late) it seems that the terms motor/engine/transmission mounts are used interchangeably. (But based on the parts websites and the diagrams, it seems there are four altogether, front, back, left, right). A few threads mentioned that a worn right hand one contributes a lot to the vibration... Are the aftermarket ones really to be avoided? Someone mentioned the compounds are not as good as the original.

ehoff121
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Location: Conn.

Re: Engine idle vibration -- How much is too much?

Postby ehoff121 » Thu May 03, 2018 12:01 pm

There are four mounts:
https://www.rockauto.com/en/moreinfo.php?pk=8518676&cc=1432959&jsn=340

RockAuto sells a kit (linked above) that contains three motor mounts and one transmission mount.

The favorite brands on their site are Anchor and DEA/MRC.
2005 Pontiac Vibe AWD - Platinum

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cq358
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Re: Engine idle vibration -- How much is too much?

Postby cq358 » Thu Aug 09, 2018 3:44 pm

Check your wiring for your IGN system as well
https://share.qclt.com/%E4%B8%B0%E7%94%B0Toyota%20RAV4%20Repair%20Manual/2AZ-FE%20Ignition/Ignition%20System/020000.pdf
something was chew chew chewing my sparking coil wire
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