Hey! I have a 4.3 2001 Blazer which i bought in February this year. Amazing and kinda exotic car, here in Europe. Few weeks ago it started to develop a really strange behaovoir: Cold starting it, was jerking when in D gear and the RPM gauage was "Jumping", beside that, could drive and no problem at all after few miles. Got home with it, parked and after few hours when i wanted to go out, it barely moved in Drive but in R was absloutly fine. This made me do some research and i bought a kit with all the solenoides. It sat for one week and when i had to move it to the garage to change them it was absolutly fine, again. Even tried some burnouts with it and no problem at all. After 50miles with it it started to jerk again when in Drive, R no problem. Ok, lets say in this case the solenoids are faulty but i have also another problem with it.


The second problem is: In the last few this, it also started to "jerk" even when i rev it in N, so it cannot be a gearbox problem anymore.

On the obd scan it gave me those erros:



Any ideas with that? Thanks.

 

Forgot to mention that didn't changed the solenoids yet. Probably i will changed them and then move to the engine

 

Not sure but could be same issue I have. The seal on the transfer case leaks and the transmission losses most of its fluid. This will cause slip and jerking over time. Make sure to check for fluid level even though you don't see any dripping on under car. Once the fluid fills the transfer case about 4 quarts the transmission should work fine, however the transfer case has a vacuum solenoid and there is a high likelihood the fluid could make its way up the reservoir and wreak havoc on your HVAC controls. Its lots of work for a 5$ faulty part.

 

Ditto on checking the fluid levels in both the transmission and transfer case. Do you have the "3-button" or "4-button" transfer case? The latter is the one with the Auto mode. The 3-button one is the one with the vacuum switch.

 

I had a very similar issue to this . Fluid level was fine , would be ok in reverse , in N or D would randomly seem like transmission was slipping and RPM all over the place. When I dropped pan to check transmission I found a simple cause on mine … Someone put the wrong tranny filter in . Had a deep pan with a shallow pan filter and the filter neck had cracked where it fits in transmission from not being supported. This was causing transmission to randomly alternate pumping air and fluid and loose pressure depending on the level of fluid changing with temp of fluid and angle of driveway .
Installed correct filter, changed fluid and all has been good .