I just bought a 2006 nissan Maxima got it really cheap knowing it had some issues. I pulled 3 codes of the car p0745, p0507 and p0795. The car starts and runs fine but sitting still and shifting from Park to Reverse or Park to drive it shifts hard and makes a thunk noise, it has no power taking off but once it gets going it is fine. I do notice a little shaking around 55mph then goes away at a faster or lower speed. also brakes are really sensitive and if I apply a lot of pressure to the brak car shakes a good bit. I know I am asking alot but any info could help about what the problems could be and the best place to start? Thanks guys!

 

P0507 - ISC SYSTEM (Idle Speed Control)
The idle speed is more than the target idle speed by 200 rpm or more.
Possible causes are:
● Electric throttle control actuator
● Intake air leak
● PCV system

The idle speed should be 675 in neutral with the a/c off and at least 825 with a/c on.

P0745 - PRESSURE CONTROL SOLENOID VALVE A (LINE PRESSURE)
The pressure control solenoid valve A regulates the oil pump
discharge pressure to suit the driving condition in response to a
signal sent from the TCM.

P0795 - PRESSURE CONTROL SOLENOID VALVE C (TCC AND SHIFT PRESSURE)
The pressure control solenoid valve C is activated to control the
apply and release of the 2nd brake and 1st and reverse brake,
and torque converter clutch.

Lock-up operation, however, is prohibited when A/T fluid temperature
is too low.

When the accelerator pedal is depressed (less than 1/8) in lockup
condition, the engine speed should not change abruptly. If
there is a big jump in engine speed, there is no lock-up.

You need a good brake job. The shaking when you step on the brakes is from a warped rotor. Sometimes the rotor can be re-surfaced and this will correct it, but most times it will have to be replaced. And there could be more than one rotor bad.

The sensitivity could be partially your perception. My Maxima brakes are more sensitive than my Lexus and after driving the Lexus for a while, I have a tendency to throw myself through the windshield when I first get back in the Maxima.

But brake pads that are worn out can grab harder than good pads. Also brake pads made from the wrong material can grab harder.

The shaking at 55 mph could be the brakes as well. A warped rotor tends to be out of balance. But it could also be your tires, which is more likely. What you can do is swap the tires from front to rear and drive the car. Out of balance tires are more noticeable on the front wheels. If a front tire is out of balance, putting it on the rear should make the vibration softer. But if it was a rear tire that was out of balance, putting it on the front will make the car vibrate harder. If you can't tell any difference, then maybe it is the brakes.

Transmission work is expensive, but very few people are willing to try and work on it themselves. Take the car to several places and get an estimate.

Here is a link for the service manual:
http://boredmder.com/FSMs/Nissan/Maxima/2006/

The file IDX.com is the master alphabetical index. But see file EC.pdf for the P0507 code and file AT.pdf for the P07xx codes. Each section has its own index and you can look up the P0xx code.