car shakes violently when at a stop in D

[bo0st]

Hey guys please help, my car shakes violently when at a stop in D.

Mods are current in profile. Motor mounts recently changed. No CEL lights.

Brakes are new, so are tires.. Have no clue where to start here..

 

[n0de]

What is violent to you? My car feels like the end of the world is coming when im stopped and the cams are loping, but thats just me. To someone else, it may feel ok/tolerable.

What rpm is your idle at when in drive and stopped. Does it shake like that in Park?

Also, your nitrous, is it on a throttle switch? How is it activated?

 

[JDT]

Are your motor mounts polyurethane? It could just be the exhaust makes it feel like it shakes abnormally.

 

[bo0st]

What is violent to you? My car feels like the end of the world is coming when im stopped and the cams are loping, but thats just me. To someone else, it may feel ok/tolerable.

What rpm is your idle at when in drive and stopped. Does it shake like that in Park?

Also, your nitrous, is it on a throttle switch? How is it activated?

It's like someone is shaking me to death .

RPM - 700 - 800, then it would rise to like 1100 - 1200 at the most as if I'm giving it gas and If I'm not HARD on the brake that baby wants to drive.

Nitrous is activated via throttle switch and only at WOT (wide open throttle) Haven't hit WOT In a long time trying to stay away from the speeding tickets.

Thanks for the fast reply.

Are your motor mounts polyurethane? It could just be the exhaust makes it feel like it shakes abnormally.

No they are OEM autozone/oreilly one's

 

[fun kart kid]

Does it stop if you put it in neutral?

 

[spawn87]

well you need to check all your TB sensors vacuum lines and i would seafoam your engine you broadly have dirty ignition. ive had a couple cars that ran like crap just because they ether didnt gap plugs right or it was just that time for a cleaning.

also clean your TB and MAF

 

[fun kart kid]

also clean your TB and MAF

Op's car is a 420A so he doesn't have a MAF.

 

[bo0st]

Does it stop if you put it in neutral?

Yes it does stop when put in neutral. Does that help identify the culprit?

well you need to check all your TB sensors vacuum lines and i would seafoam your engine you broadly have dirty ignition. ive had a couple cars that ran like crap just because they ether didnt gap plugs right or it was just that time for a cleaning.

also clean your TB and MAF

TB was cleaned as well as new plugs put in. Properly gapped too.

 

[ThunderChild]

when you put the car in D it is applying a load via the transmission. id check for vacuum leaks and a properly functioning EGR, as well as cleaning out the map sensor port, and the map sensor itself.

also, do you have an codes? i would scan it to check, get back with us after all that.

 

[n0de]

Ok Im going to toss out a few possibilities, you may have to check some of these with a voltmeter (for sensors) or just replace entirely. This may not be the easiest issue to find, just a heads up.

Throttle position switch could be bad, I believe the TCU relies on the TPS to determine engine load and shift points? Is it possible the car is in a high gear at a stop due to misinformation from the TPS?

Bad TCU

Bad torque converter or the balance weights may be missing

The only reason I believe it could be something to do with you driveline is the fact that you've replaced all of your motor mounts and only get this vibration when the trans is engaged.

I am unsure if EGR issues would cause the 10.0 earth quake type vibrations your a describing.

 

[Total Eclipse]

Usually, if it vibrates that bad when stopped in gear, but stops when it's in nuetral (or park for A/T's), that would point to motor/trans mounts going bad. Simple problem to fix, and pretty cheap too. Suprised no-one else suggested this?

 

[n0de]

Usually, if it vibrates that bad when stopped in gear, but stops when it's in nuetral (or park for A/T's), that would point to motor/trans mounts going bad. Simple problem to fix, and pretty cheap too. Suprised no-one else suggested this?

Because OP wrote this:

Motor mounts recently changed. No CEL lights.

Granted he didn't explicitly say he replaced all mounts, but he did implicitly state it.

 

[bo0st]

Turns out it was the throttle body, it needed replaced. Problem solved!