2001 w/ tach jump
 

I have a 2001 S-10 Blazer 4x4 with 137k miles. At normal cruising speeds of 45-50 mph, the tach will start jumping from 1400-1700 RPMs. It always does this on any kind of incline, but it will also do it on flat roads. The transmission was replaced about 11k miles ago at a local Aamco transmission shop. I have been told this is the transmission jumping in and out of overdrive. Is this correct? If so, should it be doing this constantly at those speeds? Any help is appreciated.

Charlie

Sounds more like the torque converter coming going in and out of lockup. Speed matches up with TC lockup in OD as well. With your right foot holding steady throttle position to maintain speed, use your left foot to lightly press on the brake pedal (just enough to get the brake lights to illuminate). If the jumping tach goes away, then the torque converter clutch is what is going in and out of lockup.

2001 Blazer jumping RPM
 

Hey everyone last year I purchased my 2001 4 dr 4wd blazer. It currently has 153,000 miles I have had no problems with it until the fuel pump went. This past weekend I had the fuel pump replaced along with a new fuel filter, spark plugs, wires, distributor, pcv valve, and an o2 sensor (not sure which one). As soon as I drove away I have been having problems with the rpms. At first it would start when I was doing around 50 mph the rpms would jump from about 1500 to 2000 back in fourth before it would change into gear. As of today even at lower speeds (10-15) the truck will start with the rpms. It seems like it's harder for the transmission to change gears but when it does it switches smoothly. Just before getting home earlier today my ses light came on so I'm going to have that checked. Any suggestions would be much appreciated as I'm starting to become very stressed out .....

word of advice.. if/when that happens, drive right back to shop.

Anyone can make a mistake and it sure helps when the job procedure is fresh in the tech's mind. A week later he wont remember the car at all, let alone what he did to it.

@pettyfrog
 

I did turn around ... The mechanic is my step-father I brought my blazer back and had him drive it .. He told me I would be fine to drive it home honestly I think he may be a bit stumped as to what the problem is he thinks it's the fuel filter that he just replaced ..