Hi, i get this weird vibration in 3rd gear at about 40-50mph or 1900rpms to about 2300 i would say, then also at about 88mph and so on to over a 100mph, i was reading stuff on the flexplate but i would think it would do it all the time then. Well if anyone knows what this could be let me know. Thanks everyone!

 

Hah!

I had this same issue about 4 months ago
Could not locate the cause for WEEKS! everything was fine (including the flexplate).

Yeah.

Change your sparkplugs. One (or more of them) is fucked, and causes this.
I know, it sounds nuts

Trust me on this one. Change your sparkplugs, and the vibration will go away.

 

Thanks for the reply, i think i will try this when i get time. Thanks alot.

 

When you say the plugs were f&%$# - just exactly what do you mean?

I have had a vibration that appeared mysteriously that has no relation to mods since the vibration was not there intitially after all my mods. Everything was fine for quite a while then I get this annoying vibration - I hadn't changed anything. As with everyone else, the vibration occurs in the higher RPM range (basically at 75MPH & above with 3.73 gears).

I too have checked/had checked professionally the rear (incl. all bearings), pinion angle, driveshaft-u-joints, installed new stock tranny mount, re-balanced all wheels. I was just about to tear into the tranny to check the flexplate and the verter.

I don't understand how the spark plugs could solve this problem as it would more than likely come from a misfiring plug(s) which should throw a code? I have the NGK TR55IX Iridium plugs that have only been installed for about 7K miles - would one expect these plugs to go bad that quickly?

-Jay-

 

one of my plugs didn't give a strong enough spark, and that caused a slight imperfection. Sort of a misfire, but not enough for the code to light up.

The one that I refer to as being 'fucked' was soaked in gasoline.