My 1996 SR5 started to vibrate just a little when it's in
Drive position and the truck's not moving. If I shift transmission into Neutral - RPMs go up a bit (from 650 to 700) and vibration dissappears.
It only happens when the engine is warm (low RPM idling). I notice it when waiting at traffic lights.

Somebody suggested to run fuel injector cleaner and may
be replace spark plugs (changes at 92K km almost 2 years ago, now I am at 157K km).

I'd like to know what causes it and what can be done to fix it.
It's not a big problem now, but I'd like to prevent something bigger to happen ;-( You know what I mean.

Thank you all
Leon

 

I would recomend the same things, normal maintenance parts. Injector cleaner, plugs, fuel filter, pcv valve, etc. Some of these may not solve the problem, but it sure doesn't hurt to replace them. If you decide to try fuel injector cleaner don't buy that cheap STP or similar cheap cleaners. Use BG 44K it costs alot but is well worth it.

Jeff

 

Sounds like your idle is a little low. I know mine idles at about 750 when it's in gear and stopped. If the idles low it will definitely cause a slight vibration that goes away when the engine is spinning faster. As to what causes it... I dunno. Is there any idle adjustment on these? I realize the obvious that they're fuel injected, but on my old (95) car it has a little screw on the throttle body you could open up to give the car a little more "breathing" room for idle if need be. Perhaps this has something similar. Then again, a tune up could be just what it is that you need as well.

 

Most vehicles have an idle adjustment but if I remember correctly you have to change it with a computer.

 

You can't adjust your idle, it is computer controlled.

I tend to think the solution will be quite easy.
I bet all you need to do it clean the throttle body and change your plugs.
Use a toothbrush and some carb cleaner for the TB and use OEM Densos for the plugs.
Throw some Techtron Injector cleaner in the gas for good measure.
I think it will run like new then.
Hope this helps!