'99 SE Limited - Automatic

Periodically, I get a serious idle drop to the point where the car feels as though it will stall.

This seems to only happen when the car is in gear, it's idling with brake depressed (standing still). Also, it only seems to happen if the car is driven prior to full warm up and at the point where the engine would idle down due to reaching normal operating temp, or at least the temp when idle down would occur.

The idle will drop or stumble down to below 500+ then stumble back up and run as normal.

Due to this symptom, I attempted to pull a code and got one indicating a malfunctioning o2 sensor. That has been replaced.

The only other work done was the cleaning of the EGR system, which was done by the dealer. According to them the intake was cracked open to clean EGR tubing. I'm wondering if their reinstallation of the upper intake was insufficient, the seal is poor, and it's intermittently gulping unmeasured air.

Any thoughts?

 

I just had the EXACT same problem on my Altima. It was the idle air control valve. When the car was not warmed up and idled high it was fine. This is due to an auxiliary valve that stays open until the engine reached temperature. The car also idled fine when the a/c compressor was on due to another auxiliary valve to provide higher idle for the compressor. When neither of these things were happening, the idle stumbled. The brake being depressed did seem to make it worse, probably because of the extra draw on the vacuum system. It did this for about 2 months on and off, then one day it wouldn't idle at all. I replaced the IAC ($130 for an Altima) and everything is better.

I did pull codes before I did this too... but had none. The IAC does not self-diagnose on an Altima, but not sure about the Maxima.

Hope this helps.

 

Also... did you clear the code and then wait to see if it came back before replacing the O2 sensor? Always a good idea, because the code could be really old or a fluke.

 

I believe you have faulty Ignition coils.

Refer to this thread.

http://forums.maxima.org/showthread.php?t=431458

 

All six coils were replaced at 60K which was about 7K ago...

 

Yes, code was read, cleared and read again... pretty sure it was no fluke.

 

TPS check that

 

had exact same problem as you. I cleaned my iac valve and it idles perfect. It no longer drops below normal idle speed.

 

^^^^ True for that one plus TB cleaned

 

how do u clean ur iac?

 

Clean the trottle body and IACV valve.

 

go to http://www.motorvate.ca/mvp.php/517 there is all the info about cleaning the TB and Idle Air Control Valve cleaning procedure is described here in the stickies. It took me like 30 min to do both. If you have any questions feel free to ask- thats what we are here for, right?

 

i recently had a similar problem, turned out to be a bad TPS and a vacuum leak. You should check those out as well as your MAF