I have subtle problem with the engine idle speed that does not happen all the time. With the engine warmed up, the A/C off and no steering wheel movement, after the car comes to a stop in gear (automatic), the engine speed remains high between 800 and 1200 rpm. Then it slowly (between 2 to 5 seconds) goes down to 650rpm where it remains and idles smooth. When the engine slows down during the transition the engine idle is rough but never stalls. The ECM does not set any engine code. I cleaned the throttle valve and the valve opens and closes smoothly.

 

Sounds like the IACV could use some cleaning

http://forums.maxima.org/4th-generat...g-dummies.html

 

Also make sure that the Fast Idle Cam is adjusted appropiately. Basically, warm up the car and check the adjuster, if there is a gap between the bolt and the stop, loosen the nut, adjust the bolt until it reaches the stop, tighten the bolt again, and voila. At least it worked for me, hope it helps...There´s a more detailed how-to if you search ¨FIC¨.

 

I will clean the IACV and set the Fast idle cam when it get warmer.

Thanks,

 

Logan: I'm new at Max details but I have a similar "bit low" low idle and a serious cold idle issue.

Are you saying there's a fast idle cam like the old school choke operated carburetor cam right on the TB ?

 

I reset the cold idle and idle set screws which were not off by very much. I cleaned the IACV pintle and seat but was not able to clean the motor shaft behind the pintle. Now the engine with the car stopped, in drive, no A/C, and no steering action, idle at 650 RPM, the engine shakes and smoothes out. The shaking does not happen at a set time interval but will shake at least once a minute for a second or two. It almost feels like a missed fire but does not stall. Does anybody know if the IACV keeps moving even at a constant idle?

 

BobMax: Yes, you can set the cold idle speed but if you set it too high you can affect the hot idle speed as this adjustment screw moves the throttle plate. If the hot idle speed needs adjustment, there is a another set srew that you can the hot idle speed on the throttle body, simular to the idle speed set screw in the old carb.

 

TMax:

I took a look in there while awaiting your response... I saw the screw on the TB that sets the idle once warm. I also saw the cam that the throttle "pin" sits on when cold.

But, I don't see the adjustment you mention where I could set the cold/may affect the hot. I think that's what I need as the cold is low and the hot is only 600 RPM. Where is that adjustment?

 

Let me try to direct you to the location of the cold idle set screw. Looking into the bore of the throttle body it is located at about 7 O'clock and below the cold idle spring assembly. If you can see it read on….
Locate the end of inner cable control for the throttle body. There should be an arm going from the cable terminal that has a roller at the end of it. The roller rides on the cold idle cam. Immediately below the cam you will see a set screw that bears up against a plunger in the throttle body that will extend and retract with changes in coolant temperature.

Before you make any adjustments to the cold idle speed, I recommend you check the movement of the plunger. If this plunger does not move with temperature change, your problem is in the throttle body and not the set screw.

Keep in mind the hot idle set is for setting the throttle plate position and the cold set screw position also controls the throttle plate position. The IACV controls the air flow that by-passes the throttle plate and is controlled by the ECM. Your 600RPM tells me the IACV and the hot idle are set correctly.

 

When in doubt.. Seafoam

 

could be bad/dirty injectors. Do 2 to 3 treatments of Lucas cleaner works wonders!

 

Hmmm... I will look in there and see what I can find.

You think 600 RM is OK hot ? It seems a little low for an automatic to me.

 

Hot idle should be 650 rpm Plus or minus 50. Mine is running at 650-675

 

OK... then I guess I've just got an initial start issue then. Thanks,