Please provide a detailed report of symptoms. Be sure to provide some background such as model year, odometer reading, recent repair history, etc.

 

i included the information in the orginal post but here it is again because because i think it did not go through.

my 96(58,000) max keep dying, when i press the clutch the rpms drop and the engine shuts off, also when the car is in gear occasionaly it seems jerky and underpowerd, recent repair was a replacement of the vent control valve done at a nissan dealership. No engine mods except for stillen cai.

 

Your car is due for its 60K maintenance very soon. You might choose to do that work right now. It includes new spark plugs and new air filter cleaner.

 

Here is some text copied from the factory service manual.


"Idle Air Control Valve (IACV) -- Auxiliary Air Control (AAC) Valve

This system automatically controls engine idle speed to a specified level.
Idle speed is controlled through fine adjustment of the amount of air which
by-passes the throttle valve via the IACV-AAC valve. The IACV-AAC valve
changes the opening of the air by-pass passage to control the amount of
auxiliary air. ... "


You may make a quick test of your IACV-AAC in the following way. With the
motor at normal operating temperature, and at idle, switch the A/C from
"off" to "maximum". Keep your eye on the tachometer as you do this. The
idle speed should dip momentarily and then recover. If it does this, the
IACV-AAC is working. If the idle drops and does not recover, the engine
may stumble, falter, and stall. The IACV-AAC may require cleaning,
adjustment, or replacement.

The correct idle speed is...
- 700 +/- 50 (automatic transmission, in Neutral)
- 625 +/- 50 (5-speed)

 

More information is needed.

1) Does this symptom occur with the engine cold, hot, or both?

2) Does this symptom occur when the car is moving, stopped, or both?

3) Is there any black smoke in the exhaust when the car stumbles and stalls?

4) Is the Check Engine Light on? Has it ever been on?

5) What makes this engine stalling problem an emergency?

 

i did idle air valve check as you suggested and it seems ok, this behavior only seems to happen when the engine is hot and it only happens occasionaly. i did not notice any smoke when this is happening. Do you think it might be a fuel supply problem. Car seems to be acting as if it was running out of gas. This behavior occurs both when car is in motion and stopped. the check engine light came on when the vent control vale broke, it turned of after the dealer repair

 

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 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.)

 

but if the ects was faulty wouldn't the engine overheet or not hold temperature. my temperature gauge stays solid regardless of weather,ac or agressive driving.

 

The ECTS has nothing to do with engine overheating. Engine temperature regulation is controlled by the thermostat.

The ECTS has nothing to do with the temperature gauge. There is another sensor for the gauge which is located right next to the ECTS.

The purpose of the ECTS is to tell the Engine Control Module (the computer) about engine temperature. The ECM uses this signal (along with others) to control the fuel mixture. If the ECM is getting wrong data it will result in a too-lean or too-rich fuel mixture.

I urge you to get a Chilton or Haynes repair manual. Haynes is the better of the two. Reading the book will help you understand the location, purpose, and testing procedure for the ECTS and many other vehicle components.

 

I posted earlier in the year, right after I purchased my Max, and I had similar problems. I checked plugs, (they were fine with no signs of detonation or carbon build up) replaced my fuel filter, changed the oil, ran a fuel injector cleaner through it, and cleaned the throttle body and MAF sensor, all to no avail. There were no codes and the check engine light never once lit up (redundancy is fun and amusing). On a road trip, the car acted as if it were finally dying, and it seemed to run out of gas with a half of a tank. Well, the culprit turned out to be the fuel pump, which probably burned up due to the malfunctioning MAF sensor sending an improper reading. All this with 180k miles.
Now, I get 24 mpg on the highway and it has not even threatened to stall out, or hesitate anywhere in the power band. I have no mods, and it burns no oil whatsoever.
The bad news is that the fuel pressure is not as easy to check as the plugs, and it is a bit more expensive to replace than some other parts, but the bottom line is that you at least have something else to check, which offers hope.
I can only offer my experience, for what it's worth.
Best wishes, and if there is anything else I can help you with, just let me know.

Sincerely,
Lee DeVine

 

it will all be resolved today as i am taking my car to a mechanic. i am however a little disipointed because i used to own a 89 max(rebuild), pounded on the engine, used cheap gas and even though the car had almost 200,000 miles on it i never had engine problems

thanks a lot for your help

 

There are some aspects of engine operation which the Engine Control Module does not check and therefore cannot diagnose. One example is fuel pressure. There is no fuel pressure sensor, so there are no "fuel pressure" Diagnostic Trouble Codes. I wish the ECM did monitor fuel pressure. If it did, you could get DTCs saying "Weak Fuel Pump" and "Fuel Filter Clogged".

It is irritating to encounter technicians who have the attitude "No Code = No Problem". They are either uninformed or lazy. There are lots of problems which can cripple a vehicle without turning on the Malfunction Indicator Lamp.