Auto EX Mounts

[WagonLX]

What's up all. It's been awhile since I've written anything on here. Since the H swap in my wagon 2 1/2 years ago, I've kind of lost interest. I still have the wagon and she's purring like a kitten, but recently I have aquired a 93 auto EX coupe. The previous owner did some things to it that I'm not sure about. This car VIBBRRRATES like a mofo at idle. Other than that it runs like a top. I've read a TSB about the front and rear motor mounts possibly being the culprits. The previous owner changed both mounts with new ones, but I'm not sure if they are right or not. I know this is a pretty common problem on these cars, so if anyone has had this issue and fixed it............

[Fleetw00d]

Photos, description, etc. of what you have would help. The rear mount is supposed to uncouple below 1000 rpm to limit vibration transmission to the body. I have a couple sitting around, but haven't figured out a good way to test how well they work. Maybe my next little project after fixing my ABS pump.

Poor ignition and fuel delivery can be a problem for rough idle as well. Is base idle set correctly?

[WagonLX]

It has the vacuum actuated mount in the rear that has been replaced with what looks to me like a cheap aftermarket part. I'm almost positive that it's causing the vibrations. I've been reading alot online since I posted and the general verdict is that these aftermarket mounts are stiffer/firmer than OEM and often times are "bad" right out of the box. The OEM ones are expensive. The lowest price I found on one is $230. I did the normal engine mount test at work today having someone powerbrake the car while I watched and the engine did move about 2" either way.Yeah I set base idle yesterday hoping that would fix it. Anyone with OEM mounts laying around?

EDIT: I see you have or have had a 93 EX Auto, did you notice any vibrations at idle?

[WagonLX]

So here's another one. What exactly is going on inside that rear mount at idle to reduce vibrations. Also, what tells that little vacuum solenoid "OK, we're below 1000 rpm's now, time to work".

[oni_cb7]

So here's another one. What exactly is going on inside that rear mount at idle to reduce vibrations. Also, what tells that little vacuum solenoid "OK, we're below 1000 rpm's now, time to work".

The ecu sends a signal through the plug to that black box on the firewall. This makes the mount looser, to absorb vibrations at idle. And stiffens up when it goes past a certain rpm point.

I hated dealing with it, so I swapped in a 91 ex 5 speed rear motor mount into my 91 ex auto. Had to plug off a vacuum port and tuck away a plug.

[Fleetw00d]

So here's another one. What exactly is going on inside that rear mount at idle to reduce vibrations. Also, what tells that little vacuum solenoid "OK, we're below 1000 rpm's now, time to work".

The mount has a rotor with a hole in it that below 1000 rpm connects the fluid in the upper chamber with the lower chamber to allow the free movement of oil between making the mount "loose". Above 1000 rpm, the rotor is turned 90 degrees to block the movement of oil between the chambers, stiffening the mount.

I'll have to check the manual to see which way is "fail safe" if the system isn't working. It may tend to fail to the "stiff" position and cause the vibration at idle.

If you search around on here, you'll find lots of complaints of vibration at idle with any automatic, EX or otherwise. I had a 93 EX coupe and currently have a 93 EX sedan and 93 LX wagon, all automatics; they all vibrated more noticeably than my two 5 speeds.

If you can see the rear mount vacuum motor, goose the throttle to get the engine speed above 1000 rpm, I believe it will change positions even if the car is not moving.