I have a 2001 Blazer 4x4 lt. This problem just started where at normal driving with light throttle input, the tach starts bouncing. Acing like torque converter clutch is dis-engaging. Before I start trying to change the solenoids out should I check other things.
BTW over 300,000 miles
Already done
oil and filer
plugs, wires and cap and rotor
throttle positioning sensor
fuel pressure regulator

 

Probably is the TCC engaging and disengaging (or is it a sharp bounce that feels like a misfire?) My trans did a sharp intermittent shudder at only 50-55mph when TCC was locked up for a while before it went out. I initially thought it was a misfire, but fixing the trans cured it.

 

No not sharp, actually very gracefull. Thanks

 

Does anyone know where the tcc solenoid is located?

 

TCC in a 2001 Blazer is a fairly complex system controlled by the PCM. You can read about it some here.

https://www.sonnax.com/tech_resource...-modifications

just drive steady 60 mph and let off the gas and tap the brake pedal lightly. Do the RPMs rise about 200 rpm? If so the TCC was engaged and you just disengaged it. Now go back steady on the gas to watch it engage again and RPMs drop. Is this what you are calling the tach bouncing? If so, the only cure is to make the engine run better so the % load on the engine doesn't disengage the TCC so much (doesn't work as hard to maintain speed). Also know that the TCC first engages about 46mph and disengages at below 43mph or so.

 

No this is happening at various speeds as long as it’s a constant speed. Then when you let off the gas JUST A HAIR you will see the rpm drop which is normal then when you feather the throttle back on the rpm will raise a bit which is normal but then without moving the throttle when the rpm drop in order to maintain it will then start surging between like 1000 and 2000 until you move the throttle a lot to stop it. You can here the engine also, it’s like you are goosing the paddle. Also this only happens after the engine gets up to a normal temp.

 

Oh and thanks for the article, boy it’s a head full of tech.

 

BTW here is the full list of what I have done to the truck this year.
2001 Chevrolet Blazer LT 4x4




New stereo.

New speakers

Replaced speaker grills and defrost vent covers

Replaced oil filter and oil.

New fuel pump

New fuel pump access

New coolant reservoir cap

Flushed cooling system

New coolant

Vacuumed AC system

New refrigerant and oil

New fuel pressure regulator.

De-carbon manifold

New spark plugs

New spark plug wires

New distributor

New brake pads

New rear drivers side rotor

New rear drivers side caliper

New 3” suspension lift

New shocks

New off-road tires 31”

Cleaned and checked EGR

Cleaned and checked IAC

New Mass sensor

Replaced 1/2 vacuum hoses

Checked tightened valve covers

New 12000 pound hidden winch

New wireless winch controls

New idler arm

New lower ball joints

New sway bar links

Transmission flush

New transmission filter

New throttle position sensor

New fuel filter