03 Monte Carlo LS
3400 v6
97,000 miles

I don't know much about the 3400. I had an 01 SS signature edition that I loved dearly and never had any problems with the 3800.

Here's the scoop...

I just bought this car a few weeks ago, and it ran perfect up until today. The gears seem to be rough on the downshift and there is a high pitch chirp and it feels like the engine is jumping when I let off the gas. Also, after first gear it shifts rough. Hoping it's not a trans problem and praying it just needs some wires and plugs. Any insight would be great.

 

Sounds like motor mounts (Broken)

Why are u downshifting it? and at what RPMS?

These transmissions aren't designed to be beat on..
They are the weak link on this car.

The "Chirp"
Could be the change in RPM's and slipping the belts...

 

I am not downshifting it manually, I guess a better way to describe it would be on deceleration. It feels like it is lagging/not jumping into the next gear when it should, and when I let off the gas, it jumps and chirps. It just started as I was coming home, so I am going to take it out and drive it around to get a better understanding of what is happening. It sort of feels like a misfire, I just don't understand the chirping.

 

Is the car throwing any codes? And have you checked to ensure the trans fluid is at the proper level? At your mileage, you should be doing a pan drop/fluid/filter change on the trans (i would do this before 100K if you can).

 

I was planning on taking it to my uncles shop to get everything done/checked out next week anyway so it will be done then. As far as codes, I do not know. No check engine light.

 

Lots of codes don't cause a CEL. Unfortunately lots of them can't be read by a regular scan tool either.

 

It depends which computer is generating the code. The Electronic Brake Control Module (aka ABS Computer) controls the ABS and traction indicators. If you have an ABS code, the ABS light goes on. The PCM controls transmission and engine related codes that cause the Check Engine Soon and sometimes Service Vehicle Soon indicators.

Also, each code is really a self-diagnostic the car runs on itself. In some instances, that diagnostic has to fail more then once before an indicator lights up. If you have a good scan tool, it can show you codes that may be pending (have not failed enough to cause an indicator, but may be coming up) vs active codes causing the indicator to be lit up on the dash.

Most code readers on the market read just the PCM. Takes the better ones to read the computers that don't usually throw codes (like the ABS computer). Just went through this with a friend's Dodge mini-van. It had ABS codes, none of my code readers were new enough to read anything beyond the PCM on an '09 Dodge. Luckily, a friend of mine has access to a newer tool that can.

There is a lot of technology in this stuff. Takes a while to sometimes figure it all out.