murata

I just purchased a 92 Nissan Stanza about a month ago and noticed that it had a rough idle speed that fluxes between 800RPM & 1,000RPM. The car also boggs out at 2,000RPM for a second and then clears up as the RPM rises.

I talked to a long time friend at Autozone he told me that if the TPS (Throttle Position Sensor) is going bad that it can cause an electrical drop out at a certain RPM, In my case 2,000RPM. This also results in a rough idle speed. You can purchase a new one for around $40 brand new or get one from a junk yard for like 10 bucks.

Now if you are handy you can test it with an Analog Ohm Meter before blowing $40, here's how...

Standing in front of your car, with the hood up, look at the big black air filter box on the right side of the engine compartment. On the left side of the filter box is an air hose running to the engine. The TPSensor is located where the box ends and the hose begins. It's a little black box with a three wire lead running into it.

The wires should be set up like this...
-------------
l l
l TPS l
l l
--l----l----l--
Red Black Red

One of the red wires is the upscale range (open air flow) and the other is the downscale range (close air flow). So when you rev the car up one lead is hot and when the car revs down the other is hot. It's basically opening and closing the throttle's air flow control as the last guy mentioned, good call!

Place the negative ohm lead to the black wire. Place the red ohm lead on one of the red wires. While connected watch the meter and rev the engine up slowly. If the ohm meter does nothing while reving up then you are hooked up to the downscale lead. When the engine revs down the meter should move. Remember one red wire is up rev and the other is down rev to make it simple.

Once you have the lead placed on the up rev lead then your meter should move as you rev the motor and the air flow door opens.

Now, with the meter working, watch it as you rev the engine. Watch as the needle moves up the range, if it sticks or jumps in an irractic mannor as you rev the motor then your TPS is on the way out, go buy a new one!

Hope this helps you out, it did the job for me.

Now, can anyone tell me if the Stanza has self-adjusting vales? Mine are clicking at random times and someone told me that they thought it was self adjusting, any thoughts?