Mainly the IAC and ECM

were is the thermostat located

You need to replace the downstream O2 sensor and have a OBD 2 code reader or scanner to erase the code

Timing chains will normally last the life of the engine. You replace it when the engine is overhauled or if it becomes noisy.

DISCONNECT BATTERY & RECONNECT AFTER 1 MINUTE

This vehicle has 4 oxygen sensors. The front two are located in the rear of the engine compartment by the firewall, one on the left exhaust manifold head pipe and one on the right exhaust head pipe. The other two are under the vehicle by the catalytic converters. They screw into the exhaust system and have a plug at the end of it attached by shielded wires that should be connected.

use the consult-II with the NATS card to erase the codes. have your keys reprogrammed too.

10w-30

location fuses in qx4

It could be the bearing in your tension pulley.

The headlights "turn out" at night when it is below 45 degrees and the car is not warmed up yet after the blinker "resets" to center when making a turn after about 78K miles. This is a power surge problem with the high beam function of the blinker arm that shuts the ballast off just long enough to loose one or both headlights. You can turn them off for one full second and back on they will be fine until the next turn or when the motor comes up to normal operating temperature.

Remove the four bolts holding the u joint retainers to the front of the differential. Remove the two retainers. Slide the driveshaft forward about one inch. Remove the two bearing cups which were held down by the retainers. Be careful to not disturb the needle bearings. Fill the two cups with grease to keep the needle bearings in place and put the two cups in the glove compartment. Reattach the u joint retainers with the four bolts and tighten down with a wrench - not finger tight. Move the driveshaft away from the front of the differential, because the front snout will spin as you go down the road. Attach the rear of the driveshaft to the floor of the vehicle with strapping and sheet metal screws or some other strong attachment method. Reverse the procedure to reattach the driveshaft. OR buy and install a Remco device.

take the plastic cover off the top of the engine 10mil socket 4 nuts hold it on when that is done go to the left side of the motor you,ll see the top cover of the timing belt 10mill socket will take the nuts off there are 4 of them take them off and you can see the timing belt and the twin cam sprockets you should be able to see if any wear is on the teeth and you can see if the belt is going bad dont try to take the bottom cover off its more work than you need to do you should be able to inspect what you need to with just the top cover off if it looks bad take to someone you trust this is alot of work to change the belt you have to unbolt the engine to change the belt

The compressor needs to be changed. There is no more pressure in it.

It keeps working but only hot air is comes out.

The coil packs are mounted directly on top of the spark plugs. Look where you would imagine a spark plug to be on a v-6, and you will see a dark plastic squarish thing with a single bolt holding it to the block, and some light gauge wires coming from it.

255-65-16

mine is a 2001 QX4 with the same problem. as far as i know, it could be a bearing problem.

make sure when you replace the pads, you repack the wheel bearings, replace the grease seals, set proper tension on the bearings, and resurface or replace the rotors

Mass Air Flow Sensor.