I own a 1993 Nissan Maxima GXE. When idling with the air conditioning operating, the tachometer jumps back and forth between 600-900 RPM and feels as though it would stall, but it doesn't. If anyone has a clue as to what the problem is, please respond.

BTW-The car ides normally with the a/c off.

 

Anyone?

 

Assuming it runs okay, what is your idle normally? Mine used to fluctuate between 500 and 700RPM. I raised my idle to ~950RPM and it's fine now, even under load (AC, brakes mashed). Plus I don't stall my car at all now, used to happen 'bout once a month before. If that doesn't really help and nothing else is happening (surging, bucking, CEL, miss, etc.) then you may just need a tuneup. Don't skimp on the Distributor Cap/Rotor though, or it'll be a REAL PITA. OEM plug wires (or NGK) and decent plugs (not platinum, VG's hate platinum) will suffice. I just got NGK wires and V-power plugs from
www.sparkplugs.com
Wires were like $72, but the V-power plugs were only $2 a piece. Took about a business week to get 'em.

 

I have a '91 SE, and i don't get any variation in RPMs with the AC on.

You might want to make sure your engine is firing alright. Meaning, check your spark plugs, wires, and/or anything that has to do with ignition and electrical part of your car.

To me (which is not very important b/c I am a newbie), I would think that you're having problems in the Power stroke of a or the piston/s. Check to see if compression is good. Also if there is any misfiring or something.

Remember, the only thing I can do to a car that would be helpful to it is change the oil. , so someone else might down my questions... but it's all GOOD!

 

There is a relay activated circuit that raises the idle once the compressor engages (so with the compressor load it maintains teh 700-750 idle). It sounds like this is cycling when it should stay on. Probably a corroded contact somewhere, a condition that plagues older Maximas in many locations.

I am aware of its existence, but never had the need to fix it, so I can't give the the nuts down specifics. You can demonstrate it functioning if you disconnect the wire on the compressor, and let the a/c "engage". You'll see teh idle go up. If you have a FSM, it details the function and location of the components.

Good luck,
John

 

I'd suggest to clean your throttle body and idle air control valve. When the ac is switched on the idle should rise 100rpm and stabilize. You probably have carbon deposits within your IACV that is preventing this increase in air flow needed to raise the idle.