According to my 95 5 speed Max ECU I have the follwing problem: "Engine Coolant Temperature Sensor". What is this-the thermostat? Car has about 110K miles on it. At idle the revs bounce around from 300 rpm to 800 rpm. Acts like it is going to stall. If I use AC the computer kicks the revs up to 700-800 rpm (which is normal for car when the ac is on). Any ideas? Does Dan Martin still live in these here woods? Any thoughts would be GREATLY appreciated.

 

I was just playing with this today so hopefully I can help you out. Basically the ECTS is a thermistor that registers the temperature of the coolant and changes its resistance based upon the temperature reading. If you have a Haynes manual see page 6-11. Basically replace the sensor and you should be good.
I doubt that the sensor is still good, but if you wish to test it here's the procedure:

The test for a bad ECTS is an electrical resistance test. Instructions for this test are in Chilton (page 4-15) or Haynes (page 6-11).

ECTS test procedure
You may want to test your Engine Coolant Temperature Sensor. This is easy enough, requiring only an ohmmeter.

On the 4th Generation Maxima engine the Engine Coolant Temperature Sensor is located in the water outlet tube close to the engine end of the upper radiator hose. There are two sensors in that area. The one nearest the hose is for the dashboard temperature gauge. The ECTS, the one you're interested in, is right next to the the gauge sending unit. There is a good picture of these sensors in the Haynes manual on page 3-7.

With the engine cold, disconnect the ECTS and measure its resistance.
Reconnect the ECTS, start the engine, run it until fully warmed up. Stop
the engine, and repeat the resistance measurement. The "warm" reading
should be a much lower value than the "cold" reading.

The Chilton Maxima shop manual gives these specs:
Engine coolant temperature 68F, ECTS resistance 2.1 - 2.9 Kohms
Engine coolant temperature 194F, ECTS resistance 0.24 - 0.26 Kohms
(Roughly a factor of ten difference.)
Originally quoted from DBM himself.


-hype

 

If the ECU detects a failed coolant sensor, it may be running the cold idle fuel maps, which is rich. This would explain the engine being down on power and not performing well off/at idle.

The coolant temp sensor is located next to the front cylinder head on the driver's side. It plugs into a metal coolant line that routes next to the head. You want to check the connector to make sure the connection is good. If it is, the sensor may be bad. Best bet is to find a service manual and diagnose the problem as per the manual.

 

Keven you don't usually return emails, but you always post on my threads Want to help me fix some problems? I love my car, but lately I've been finding too many things that don't seem right
http://forums.maxima.org/showthread....hreadid=120697
-hype

 

Thank you both for your responses. I will check the sensor out (now I know where to look and how to test it). You saved me some big $$$