Torque converter problems?

[ae2598 at wayne.edu]

A friend of mine just got a '90 Buick Century for real cheap, but it had
drivability problems.  The way it was reported, it would run fine until it
warmed up fully, usually like, 1/2 hour or so, and then it would stumble,
stall, and just generally run like crap.  Turned out it was the TCC lockup
solenoid!  Apparently it would stick in the locked position, and wouldn't
let the engine idle properly.  Makse sense, and the TQ converter
functions similarly to a clutch below the stall RPM, I do believe!

 On Thu, 15 Mar 2001, Shannen Durphey
wrote:

> This isn't necessarily a sign of a failing tcc.  There's a definite possibility
> that the problem is caused by the engine running poorly.  When the tcc is unlocked,
> the converter "absorbs" engine vibrations.  Once it locks up, the engine and
> drivetrain are locked together.  
> 
> My experiences with 700R4's, fullsize pickups, and disconnected tcc's is that any
> extended driving without the tcc connected ends with a visit to the trans
> rebuilder.  It's just not a good idea to do this for a long period.   You can press
> down lightly on the brake pedal to force the tcc off during a road test.
> 
> Misfires like to show up around 30-40 mph, under medium acceleration, when the tcc
> first engages.  I've also felt misfires in trucks around 70-75 on the highway which
> were reported as trans issues.  Changing from OD to D while driving will change the
> load/rpm of the engine and will often seem to
> "cure" a misfire related vibration.
> 
> Migh want to check the condition of the tune up.
> 
> Shannen
> 
> 
> 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
> >
> ----------------------------------------------------------------------------
> To unsubscribe from gmecm, send "unsubscribe gmecm" (without the quotes)
> in the body of a message (not the subject) to majordomo at lists.diy-efi.org
> 
> 


----------------------------------------------------------------------------
To unsubscribe from gmecm, send "unsubscribe gmecm" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org