Vibe shaking

[Kevinsordid123]

Bought a 2009 gt with 130k on it. Car is awesome but has one issue. When it starts it idles a little rough and when I put it in reverse I can feel the car vibrating, as well as when I am at a stoplight. No issues when I’m driving only when I put it in reverse and sometimes stopped at a stoplight it shakes. What could this be if anyone has any experience?

[joatmon]

welcome to genvibe

might be a couple of things.

first guess is maybe a weak motor mount, although I'm not sure how to check them. One way is to look at the engine (from the safety of the side of the car) while someone else stands on the brake, shifts between drive and reverse, maybe steps on the gas to put extra torque on the engine, and look for excessive engine movement, although "excessive" is a subjective term hard to quantify with no frame of reference

also might be a low or rough idle, which could be a tune up kind of fix. When its shaking at idle in gear, what RPMs does the tach show?

[andrewclaus]

Just to add some info to this old thread, my '07 developed a rough idle recently. It sounded like a common problem noted here over the years, so I looked at several threads for solutions. I had replaced motor mounts last year for another issue, and the car is well tuned up--clean MAF sensor and throttle body, newer spark plugs, and is in mechanically great shape at 230K miles, no DTCs. Before I tried to chase a vacuum leak, I thought I'd try a bottle of Techron I got last year in a two-fer sale at the parts store. Within minutes, the idle smoothed out.

[vibedrivermatt]

Did you unplug the battery by chance?

My car always idles rough for awhile if the battery cable is disconnecred for any reason. The cars computer or ECM needs to relearn how to idle smoothly everytime battery is unplugged for an extended amount of time.

Its impossible for me to say if this is the cause of your issue but its a possibility, especially if your battery was unplugged recently .

[andrewclaus]

Did you unplug the battery by chance?

My car always idles rough for awhile if the battery cable is disconnecred for any reason. The cars computer or ECM needs to relearn how to idle smoothly everytime battery is unplugged for an extended amount of time.

Its impossible for me to say if this is the cause of your issue but its a possibility, especially if your battery was unplugged recently .

Yeah, the battery went completely dead over the winter, < 1V. I disconnected it and cleaned terminals before recharging it. Good thought. But I've had that rough re-learning period before. This was worse and lasted weeks.