MacGyver

I tried increasing my idle speed, but the idle speed control screw doesn't do anything. I turned it counrt clockwise and it does nothing....i tried doing disconnecting the throttle position sensor harness connector and doing it that way, but it stalled after it started.
I turned the idle speed control screw a couple turns...should i turn it until it's out....it just seems like it does nothing. Anyone else have this problem?

BIGMAX

Same here, I tried adjusting it once,but like you said the idle never changed it stayed at 600RPM

Maxfreak

I did the same thing about 2 weeks ago and also noticed nothing. But two nights ago I did disconnect my battery for about two hours to reset my ECU and did notice that the idle did go up to about 850. I think the resetting of the computer must have made the idle where I originally wanted it. Try it, ya got nothin to lose.

Nismo87SE

You have to unplug the Idle up solenoid harness to adjust the base idle.

Eric L.

Actually, if you follow the directions in the repair manuals (Chiltons or Haynes, don't have the Nissan one so I dunno about that one), the idle speed can be adjusted temporarily by turning the idle air control screw.

But a few days later, the ECU will adjust itself and your idle will be low low low again. It happened to me that way. I just gave up and have to live with the low and slightly vibrating idle.

I just had my spark plugs changed and it seemed to make my idle smoother. My Max still idles at 650RPM in drive, but it doesn't vibrate as much anymore.

MacGyver

There has to be a way to adjust it and keep it at the adjusted idle speed....someone must know!

ny96max

ok, so to raise you idel just follow these steps:
1) warm up your car to normal temp and shut it off
2) disconnect the TSP clip off the throttle body(furthest away from you out of the 2)
3) start up the car again (car will hesitate but shouldnt stall)
4) while running find the screw and turn it counter clock wise till the idel starts to go up
5) stop when the idle reaches the rpms you want
6) shut off car again
7) re-connect the clip to the throttle body
8) re-start the car and check out the new idle.....

*9) if you have time, reset the ECU, unplug both the + and - terminals for an hour, reconnect and let car run for 10min without turning anything on (NO LIGHTS,FANS,STEREO,ETC..) or touching the gas (NO REVING THE ENGINE!!)

HOPE THIS HELPS!!

JohnnyMax

The ECU (computer) controls the idle based on the program in the chip. It can vary the throttle position, throttle bypass, timing, etc to maintain the programmed idle speed regardless of what you try to do . The idle screw is a backup to keep the engine from stalling should the control system fail.
So to raise the idle you have to fool the ECU into thinking a higher idle speed is needed.
Running the A/C moves the idle speed up to approx 950 RPM, you could try switching on the A/C. The ECU should then bump up the idle.
I suppose you could also disconnect the compressor clutch (to eliminate the load of the compressor)

Why not just fix the motor so it idles at the correct speed?

MacGyver

1. I tried disconnecting the trottle sensor thing...just like the directions (i did this all before a few times) and it starts like normal...revs up, but then it comes down and stalls

2. What do you mean "fix the engine" it runs fine, the problem is when i put an extra load on it like the light, fan, power steering. It's at like 600, but then with the extra load it drops to 500
turning at night in nutral it drops below 500....it hasn't yet, but i fear it may stall

JohnnyMax

Ok,
The ECU should "sense" additional loads like the lights and PS and readjust the idle. It does this via the idle air control valve (IACV), be sure its connected, wiring looks ok etc.
If that seems ok you can test the valve with an ohmmeter. The procedures in the manual.

Hope this helps

Daniel B. Martin

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)

There are other engine parts which play a role in maintaining the right idle
speed, but the IACV-AAC is the first thing to look at.

96BLUMAX

iTrader: (3)

For me the idle went up for a few days and then returned to normal, but I haven't had any problems with it dropping below 600. Before I changed the screw it was getting enough air through that part of the throttle body, which caused the car to stall when braking.

MacGyver

what if it isn't the IACV-AAC valve. There is no hope?

Daniel B. Martin

If the idle problem does not lie with the IACV-AAC valve then you have to embark on a wide-spectrum diagnostic program. Clean the Throttle Body. Search for vacuum leaks. Test the Throttle Position Switch, the Mass Air Flow Sensor, the Oxygen Sensors, the Engine Coolant Temperature Sensor, the Crankshaft Position Sensor, etc. Another Maxima.org member said his dealer cured a similar problem by cleaning out "dust" which had accumulated in the intake tract.

96sleeper

iTrader: (4)

Go to autozone and buy a can of throttle body cleaner. I cleaned mine today and it fixed my low idle problem and greatly improved part-throttle acceleration. Depending on how many miles you have, it will be absolutely nasty. Be sure and clean it good, make sure the bottom edge of the valve is free of debris and smooth.

bigtexan7

Raising idle speed also raises gas consumed.