Engine vibrations, who has them?

[Ross]

Hey all,

My EJ25D, which I've just done a manual conversion on, has a low frequency vibration at around 1800-2000rpm. Only noticeable when free reving with the car at rest. It feels something out of balance -- you can feel it through the whole car, not to an alarming extent, but it is noticeable. Can also hear it.

 

The engine runs perfectly otherwise, no misfires etc.

 

Is this kind of thing normal for a manual EJ?

 

The flywheel is off a Ej20 twin turbo...

[Legacy777]

How old/worn was the flywheel on the EJ20? Was it a stock flywheel or aftermarket? If aftermarket, is a standard weight or lightweight flywheel?

[Ross]

It is a standard flywheel from the EJ20R, and looked to be in good condition. The donor car had done 160,000km (~100,000miles). Clutch is a new excedy one (turbo style).

[GeneralDisorder]

How is the rubber on the harmonic dampener? Mushy engine mounts? The flywheel would not be my first suspect.... does it have an aftermarket filter/intake? These have been known to cause issues with harmonics at certain rpm.

 

GD

[Ross]

Are the engine mounts different between manuals and autos? They are the factory auto ones at the moment, they look OK but are certainly not new -- the car has done about 200,000km.

 

The pulley damper rubber is a little cracked looking. Do these casue a vibration that can be felt when the rubber goes bad?

 

The intake system is all standard.

[Legacy777]

In the states, there can be some difference as to whether they're liquid filled mounts or not....that was primarily due for engine noise damping. However they serve the same purpose and should be interchangable.

[Fairtax4me]

What transmission mount did you use?

 

Checked everything under the car for proper body clearance?

Is the pitch mount installed properly?

[Ross]

Trans mount and crossmembers are all from the manual car. Pitch stopper is installed correctly and in good condition..

 

There is good clearance between everything....

[Fairtax4me]

Is it a shaky feeling like a misfire, or more like a buzz type of vibration?

 

Didn't knock a heat shield loose by accident did you?

There are some rubber dampeners that go between the transmission mount brace and the cross member, are they in good shape?

Edited December 13, 2010 by Fairtax4me

[Ross]

It's quite a heavy shaking, like a misfire but not as 'sharp'. But definitely a shake rather than a buzz. Yeah those bushings looked pretty good.

 

Everything else with the engine seems fine, other than a suspiciously good fuel economy figure... 10km/l (23.5mpg) for mixed city/open road with a fair bit of AC use, roof racks, and a 5th gear that puts it at ~2900 at 100km/h....

[Fairtax4me]

Ok, I was thinking along the lines of the buzz.

 

Not sure, that might have something to do with the weight of the flywheel + clutch assembly.

The 2.0 clutch assembly has a "pull type" pressure plate, while the 2.5 (non turbo at least) are "push type".

Of course I can't find any flywheel weight specs for either.

 

Mileage sounds good for easy mixed driving. I'd expect approx ~30 mpg at 55-60mph. Might do better if driven right.

2900rpm seems fast at that speed. You got 4.44 FDR?

[Ross]

Oh OK, maybe my mileage expectaions are a bit low then. Taking it on a trip tomorrow so we'll see how it goes.

 

Yeah I'm thinking it may be that the flywheel is lighter than what would normally be used on the 2.5. It's quite possibly a lighter than normal flywheel fro the ej20 since it came off a 206kW version. The engine is very rough below 1500rpm if it has any load on too (yes, I know that's quite low revs) -- more so than I'd expect. This also points to a light flywheel.

 

If this is the caes then I'll leave it be and not worry about it.

 

Yeah it has a 4.44 fdr. I wanted the low ratio as I'm setting this car up to tow my suzuki samurai on it's trailer on long trips. Should purr along quite nicely at 2900rpm. Just need some heavyer springs and new struts for the rear now.....

[Fairtax4me]

The engine is very rough below 1500rpm if it has any load on too (yes, I know that's quite low revs) -- more so than I'd expect. This also points to a light flywheel.

 

Yeah, that sounds like a the flywheel is too light. You will get some "chugginess" below 1500 rpm under load. The weight of the flywheel will affect clutch engagement from a standstill more than anything, but you will also feel the effects of the lighter weight at lower rpm.

Why it shakes the car probably some kind of balance issue, but if it's livable, then like you said it's not worth pulling the engine again to change it.

 

There are people on here who swear by Delta Cams for getting more bottom end grunt out of the EJ. It might be something worth looking into if you have a lot of hills to traverse.