Chevy Trailblazer Acceleration Problems

I just bought an 03 Chevrolet Trailblazer ext. Problem that I’m having is, when I’m driving doing 50-65 it acts like it accelerates and then slows down? N keeps doing it!!
Please help me with this problem..
Thank u.

Answer: If you mean that the engine is revving up and down, not that the truck is actually speeding up or slowing down, then this sounds like a transmission problem.

There are a few things in the transmission that can cause this. At that speed, the transmission should be in 4th gear- overdrive. Also, between 3rd and 4th gear is what is called TCC- Torque Converter Clutch lockup. This almost feels like another gear, but it really is not. It is where the internal portion of the torque converter locks up getting ready for 4th gear.

You could have a problem with TCC coming on and off which would give you the feeling of acceleration and deceleration because the engine RPM will go up and down as TCC goes on and off. The same thing could be happening with overdrive- it may be going in and out of 4th gear. This would give an even more pronounced sensation than a TCC problem.

When the problem is happening, put the shifter in the “D” range, not Overdrive- D with a square around it where you most likely always have the shifter. What this will do is stop the transmission from going into 4th gear, so if the problem quits, then you know that the problem with your Trailblazer is in the overdrive of the transmission.

If this procedure makes no difference, then the problem could still be in the TCC system of the transmission.

There is not much you can do to your Chevy Trailblazer other than checking the transmission fluid level and condition. Aside from that, a mechanic will have to scan the computer for trouble codes and drive your truck while watching data on his scanner to watch what the transmission is doing.

Chevy Blazer Crank sensor Code

I have a 2000 chivy Blazer that I have replaced the engine in and the timing chain but it throwing a check engine light and the code is reading for crankshaft error or something like that. The crank shaft sensor is not the same one that was originally in it. That was used in another truck. Do i have to get this crank sensor flashed or what?

Answer: By telling us “crankshsft error or something like that” is not very helpful. There are several engine light codes related to the crank sensor. We need to know the code number.

Aside from that, yes i would put the correct sensor back in. No, there is no re-flash for this.

Check to make sure you got the engine timed properly.