I have a dodge sx 2.0, and I have a fairly well rounded knowledge about how cars work, but I'm no mechanic. And about 8 months ago my engine started rocking back and forth when ever I would even just lightly step on the accelerator especially when stopped. Or accelerating while already moving at a constant speed, and when ever the brakes or applied. The engine will rock so much that the exhaust actually hits the bottom of the car really hard and you hear a clunking noise. I can do this at a stand still with the brakes applied as well.

I've had all the motor mounts replaced twice now... once by me and once by the dealership. And the problem still continues. So I'm not exactly sure what is wrong and can't really locate where the problem is coming from.

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I also have another issue that my other SX does not have, but the same one does it idles really roughly, not so much in neutral as in drive. But it shakes hard I've replaced and gapped the spark plugs, coil pack, cleaned fuel injectors, replaced belts, replaced air filter, cleaned throttle body.
I've also read about a lot of other people with neons having this problem, I'm not really too concerned I just find this one a bit odd.

Only error code I also get is for the battery sensor, which is missing.

Any help to either of these problems would be greatly appreciated.

 

All motor mounts...how many are there? Just asking as people usually miss one. Just double-checking, if you will.

If it shakes badly, it's one of three possible things (or all): either the torque struts aren't aligned, the motor mount wasn't installed back in the exact same factory-specific location or the motor mount is still bad as it wasn't actually replaced.

While we're at it, the transmission mount is still good?

 

I'm not exactly sure where the transmission mount is but these mounts have been replaced twice in the past year and a half, the one below the air filter, the one that is near the pulleys next to the engine, and both torque struts below and above pulley system. Am I missing one?

The first time I did them about a year and a half ago, and there wasn't really any problems, but then about 8 months ago the engine started rocking back n forth depending on if i gassed or braked, so i took it in the dealship and got the mounts replaced and there was no difference made at all in the rocking or shaking.

I'm actually starting to get exhaust leaks because my exhaust is smacking the bottom of my car so hard.

Incase you're wondering why I replaced them twice, I've drove the car about 150,000km in a year.

 

trans mount is under the battery tray its an easy one. but you have them all done thats it. the bottoming out could be worn/weak front springs or if your running 50 series tires up front. if the rocking back an forth can be done by hand the mounts are torn and the torque struts are slightly out of alignment but its easy to realign it back

 

I'll try a realignment, do you know if the haynes manual for neons has the correct torque strut alignment measurements for 2004 sx 2.0? Just wondering because I know that these cars have been mass produced so much that even a lot of the same models have slightly different parts.

 

I have a link to the procedure in my signature, along with the alignment specs.