Okay-I;m in Central Texas and it is 28 degrees right now. When I left for lunch it was 26, and when I started my 95 Max, it caught right away, but then stalled. When I tried again, it immediately caught, but I had to lightly rev it a bit to get it to stay at the cold/fast idle. After that, it drove fine. I have noticed on some cool mornings, that if I pull out right away and come to a stop in the first 15-30 seconds in Drive (yes, an auto tranny), then the idle drops to about 500 rpms (way too low) for only that first stop. Afterwards, it drives fine. Any ideas?

 

Your fuel injected engine has an Engine Coolant Temperature Sensor. This sensor sends a signal to the Engine Control Unit (the computer). When the ECTS sends a "cold engine" signal the ECU responds by instructing the fuel injectors to deliver a rich mixture. The rich mixture helps a cold engine to start and run smoothly during the warm-up period. This is similar to the operation of the choke on a carbureted engine.

There are other problems which cause cold starting and driveability problems, but the ECTS is the first thing to check. This can be done with 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 vicinity. The one nearest the hose is for the dashboard temperature gauge. The ECTS, the one you're interested in, is adjacent 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, and 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.)

The ECTS is a relatively inexpensive sensor and something the home mechanic can replace without special tools.

 

Daniel,

I think you've posted that reply 30 times since you've been here.

 

You're right! I keep it in a file and do cut-and-paste. That's a big time-saver.

 

I was having the same problem too on my 95 SE Auto. I bought some of that ZMAX additive and put it in. The car runs a lot better now and shift so much smoother, i definetly recommend trying some to any of you. It's 34.95 if you look online and it's guaranteed to improve mpg by 10%
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DakotaSex cam

 

It also affects the engine after it has warmed up to operating temp. If the sensor tells the computer erroneous readings the computer will shut the fuel pump off.