Torque converter problems?

[Roger Heflin]

Gabe wrote:
> 
> Got a father-in-law with '92 4x2 Chev full size pickup with either a 4L60 or
> 700R4 tranny & a 350...
> 
> Recently it has developed a pretty nasty vibration/shudder it seems when the
> torque converter locks up under light throttle & at low RPMs...  As a side note,
> my work van (92 Astro) does the same thing & has for the last couple years (I
> only put about 4-5K miles on it a year).
> 
> Is this a sign that the torque converter is preparing to expire and send
> shrapnel thru the tranny or just that the ECM is getting a bad signal from
> somewhere or is in need of reprogramming for better lock up points?  Don't
> really have much experience with lock up converters & OD tranny's - have always
> had TH400s or TH350s.
> 
> We were contemplating disconnecting the wires for the lock up converter for the
> time being to see if that would cure the problem for now.
> 
> TIA for any input.  BTW, the truck has not had any programming work done to it.
> 
> Gabe

It is almost always a miss.   Minor misses seem to show up at low speeds (right
where the TCC locks up in high gear 45-55 or so), and are obvious if you realize 
what is going on.   Low throttle is also  required as higher throttle unlocks the
TCC and hides it.

Mine did this, it when away after a valve spring broke and was replaced, I suspect
it had been partially broken/weak for a while).

My car has also done this when it has plug wire problems, after the plug wires 
were fixed it went away.  So look for a miss, it is more often than not the cause,
and really nothing to do with the TCC.

				Roger
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