Help, car jerks/rocks when accelerating

It seems when I accelerate or hold the gas down just a little while trying to maintain a certain speed (or cruise control is on), the car will kind of rock a bit. It's not terrible but definitely noticeable. I was thinking this might be due to a bad motor mount(s). I replaced the top one not too long ago but I'm thinking maybe there's another that needs to be replaced. Does anyone know of a good/easy way of checking the mounts to see which one needs replaced the worst? I was also thinking that it could be some kind of fuel injection problem? It's the most noticeable from 5mph~50mph. Your comments/suggestions would be greatly appreciated. Thanks.

Classic defective EGR valve. Pull the vacuum line off the EGR valve and plug the line. Then drive it. If you notice the problem goes away, replace the EGR valve.

+1^^^^^^^^^^^^^^^^^^

Your top motor mount is bad regardless. Its over 10 yrs old. Time for a new one :)

+1^^^^^^^^^^^^^^^^^^

Your top motor mount is bad regardless. Its over 10 yrs old. Time for a new one :)



And, it's about the easiest thing to do ever on a car.

Classic defective EGR valve. Pull the vacuum line off the EGR valve and plug the line. Then drive it. If you notice the problem goes away, replace the EGR valve.

Thanks. I pulled it off/plugged line and it did seem to help but I'll have to drive it around a little more to know for sure if that is the problem for sure. Does it hurt anything by driving it around with the EGR line off for a little while? Say a trip to town and back?

+1^^^^^^^^^^^^^^^^^^

Your top motor mount is bad regardless. Its over 10 yrs old. Time for a new one

I replaced the top motor mount about 7 months ago...but I'm sure the others need it as well.

Readdddddd:

Additional TAM requirements when replacing any of its four components When changing any of the four components of the TAM (((>Torque Axis Mount<))) the following should be stressed. http://www.saturnfans.com/forums/images/smilies/yes.gif

Attached and supporting the Engine (http://www.saturnfans.com/forums/showthread.php?t=73563#) Strut, often overlooked, is a bracket in which one end of the strut sits. This bracket, upon close examination, is afixed to the engine cradle. However, it is attached with two bolts/fasteners. The nuts can be reached only from underneath the cradle.

These two nuts, should be loosened after any work is done on any of the TAM's four components. Therefore, after replacing either the (upper) Engine Mount, the (lower) Transmission (http://www.saturnfans.com/forums/showthread.php?t=73563#) Mount, the Transmission Strut, and/or the Strut-to-Engine, it is important to loosen these two nuts/fasterns and then re-torquing (Spell ?)them .

This effort accomplishes the removal any "fore/aft preload" from the Engine Strut. http://www.saturnfans.com/forums/images/smilies/snide.gif

Torque = 37 ft lbs.

-Luke-

Readdddddd:

Additional TAM requirements when replacing any of its four components When changing any of the four components of the TAM (((>Torque Axis Mount<))) the following should be stressed. http://www.saturnfans.com/forums/images/smilies/yes.gif

Attached and supporting the Engine (http://www.saturnfans.com/forums/showthread.php?t=73563#) Strut, often overlooked, is a bracket in which one end of the strut sits. This bracket, upon close examination, is afixed to the engine cradle. However, it is attached with two bolts/fasteners. The nuts can be reached only from underneath the cradle.

These two nuts, should be loosened after any work is done on any of the TAM's four components. Therefore, after replacing either the (upper) Engine Mount, the (lower) Transmission (http://www.saturnfans.com/forums/showthread.php?t=73563#) Mount, the Transmission Strut, and/or the Strut-to-Engine, it is important to loosen these two nuts/fasterns and then re-torquing (Spell ?)them .

This effort accomplishes the removal any "fore/aft preload" from the Engine Strut. http://www.saturnfans.com/forums/images/smilies/snide.gif

Torque = 37 ft lbs.

-Luke-

I'm almost positive I did this but I will loosen them again and re-torque. Maybe I didn't loosen them enough the first time...We are talking about the two nuts under the passenger's side of the engine that are accessible through two holes..?

The jerking seems the most noticeable in the 40~50mph range. My "Service Engine Soon" light came on after disconnecting/plugging the vacuum hose from the EGR valve. Not sure if this can really cause any damage but I will try it again soon.

Disconnecting the EGR valve for a few days won't do any damage.

Classic defective EGR valve. Pull the vacuum line off the EGR valve and plug the line. Then drive it. If you notice the problem goes away, replace the EGR valve.

Well, I've driven it for a while with the vacuum line off and it seems like it helps but doesn't totally eliminate the problem...is this possible or am I just thinking it's helping? I mean, it seems to be smoother in cruise control but you can still feel a slight rock when accelerating a bit. If disconnecting the vacuum line is supposed to completely eliminate the rock then I guess I can rule out the valve...If it's not that EGR valve though, then would a bad motor mount(s) be the next suspect?

Well, I've driven it for a while with the vacuum line off and it seems like it helps but doesn't totally eliminate the problem...is this possible or am I just thinking it's helping? I mean, it seems to be smoother in cruise control but you can still feel a slight rock when accelerating a bit. If disconnecting the vacuum line is supposed to completely eliminate the rock then I guess I can rule out the valve...If it's not that EGR valve though, then would a bad motor mount(s) be the next suspect?

Never mind. About ~$75 later this did indeed fix the problem. Thanks again for your help.

Glad you got it fixed!