Lethaldosage423

Ill start by saying i have the 4.0 V6 Automatic stang
When im at a stop light, there is a strong vibration like the whole car is shaking, whats causing this?

could it be my TPS on its way out or even my tune?

thanks for the help

Mr. Ugly

Exhaust?

Or maybe the harmonic balancer on the engine is separating? It's a two piece that's bonded with a rubber ring between them. Saw some pics of one that had gotten torn up.

Had the same thing happen on my 92 Jeep 4.0L.

Natalya[AF]

It's probably the HVAC if you have it turned on. Turn off the AC or heat before you stop and the car shouldn't do that. I have a tune as well but my car has been doing that since I got it so I seriously doubt the tune, unless this vibration is something new.

The Potato

Does it sound like metal hitting against metal?

my first mustang

Loose plug wire? Vacuum leak? Try reinstalling the tune. Use your tuner and raise the idle 50 rpm. This happend to me when I went to Florida & used the AC all the time.

Torch Red GT

Does it sound like its coming from under the car? I have this problem too and have a 4.0 v6 automatic as well. Does it only vibrate when in "Drive" or "Reverse"?

Lethaldosage423

Thanks alot for the help guys, its probably the HVAC system pulling power
im really hoping its not the harmonic balancer pulley but im going to check it out
and it does it when its in drive, at long lights ill drop it into neutral just to stop it, ill check all of these things out

thanks again guys!

tx_zstang

I think I know the 'vibration' you are talking about, or if its a rattle, that's different. I think you're referring to the situation that when you come to a stop and let off the throttle, the rpms drop and the engine just runs rough fir a bit or for awhile.

When you're at a stop and it does it, note your RPMs. You can try putting it in neutral and/or reving up the rpms just a little to see if it stops or helps, as well as (as suggested) turning off your a/c or defroster (just to see if it makes a difference).
You might need your idle speed rpms tweaked in your tune, depending on the rpms. (the sct had a setting you can adjust, if your tuner activated the adjustment.)
And yes, the A/C and defroster running can affect idle smoothness, too.

If you haven't changed your plugs in awhile, that could hurt, too, as well as a restricted fuel filter. But both should cause running issues at higher rpms, too, not jsut when slowing to an idle.

You can do a datalog of when it does it and get a better idea of what is going on, too, and you'll see how low your rpms drop.

let us know what you find out.

illin

I think there are two different issues being tracked here, but TX is on it.

Try dropping your idle speed 100 rpm with your tuner and see if it vanishes. Even with a custom tune, it is easy to do. I have a Diablo...so someone with an SCT will chime in and tell you how to modify your custom tune. You should have some control over idle speed, TCS, fan speed etc.

rl05mustang

You have a GT takeoff single muffler listed as a modification. There is a dampener on the original V6 muffler that removes vibrations. Try getting a muffler clamp and fabricating a bracket to allow the dampener to bolt up in the original position.

I did this to my V6 automatic after switching to a single GT muffler after noticing the increased vibration. Afterwards it was all smooth again!