I am having problems with my 94 nissan maxima with 31K origional miles. when its cold it idles at around 700-800 rpm but when it warms up the idle drops to around 500 rpm. as the rpm's drop to 500 the car begins to vibrate. Also when I turn on the heater or any electrical component, headlights, roll up windows the rpm' s will drop and the car will begin to vibrate. The vibration only happens when the transmission is in Drive or reverse. While stopped at a light I usually switch the tranny into neutral and that will smoothen out the engine. I have also noticed that the exhaust will smell like sulfer "rotten eggs" I did notice that s vaccum line was disconnected from the top left of the intake manifold, I reconnected it but didnt notice much of a difference in the idle. I also tightened up the main hose screw on the fuel rail. it smelled like gas everytime I started it up. Could the rough idle be the fuel injectors, catalitic converter, o2 sensor, voltage regulator. Please help...

 

lots of cars RPMs lower with electrical load as the alternator has to work against a increased load, that also increases the engine load. The rotten egg smell has plagued my Maxima since I've owned it. Possibly the Cats, but more likely just a common maxima problem, sometimes related to fuel brand. I doubt a 31K maxima would have bad cats, if they are bad, drive around and they should glow red if they are plugged, which I doubt. Does it still smell like gas? Has the car ever had a tune up? Does it have original EGR, plugs, wires, etc...Basically I would try some fuel additive like STP red bottle fuel additive. Sometimes that smooths my idle. If not work on raising the idle-Chilton has a pretty cheap Nissan Maxima manual.

 

I just took it in for a major tune-up and they replaced cap, rotor, plugs, fuel filter, pcv, and some other stuff. could the problem be clogged injectors. Does anyone recommend a gas additive to clean injectors.

 

A 94 with 31K....I should be so lucky.
There is an idle adjustment circuit in the car that is supposed to compensate for extra load on the engine. Basically to hold the idle at roughly the same RPM regardless of the load. Usually referred to as the IAV (idle adjustment valve) or IACV. (control valve). You might get a manual and start with that. Easier yet is to continue to look for vacuum leaks. Those will kill idle faster than anything. If one or more of your injectors is not working properly, you could be running on less than 6 cylinders, which also could be your problem.

Has the car been sitting for a while without being driven (maybe a dumb question with 31K on it)? If so, the fuel may be gummed up in your system and the fuel additive suggestion might help.

One other thing- is this an SE, or GXE?

 

Its a GXE. I bought my 94 Maxima from a woman who live less than 2 miles from work. I seems that she didnt drive much, so the car probably just sat around. I purchased the car from this woman in California and brought the car to brookly NY. It seems that the cold weather is making it run funny.

 

I have a '94 Maxima GXE with ~82k miles. I had the exact same symtoms as you described, I think. I feel the shakes even in the steering wheel at the stop sign, and it goes away in Neutral or Park. I didn't have the idle rpm drop as noticeably as you described, though. Just the vibes out of P or N, and I don't remember it being related to any electrical loads to the engine.

Before I get your hopes up, I haven't been able to fix it yet.

While spending time to visit different mechanics and dealers, somehow the symtoms got better, and now it's barely noticeable. Lasted maybe a few months - during the warm months, though. It used to be so bad that I could feel it on my neck and cheeks if I held the steering wheels tightly. Someone suggested starting with tune-up. Did the tune-up help at all? At first, I thought it was the engine mount, but haven't gone down that route yet.

I'm keeping my eye on it for now. Let me know if something fixes it. I'll post it if it comes back as well.

 

cna y'all say "DRY ROT"?

 

Do you feel that the vaccum lines are dried up and leaking

 

Vaccum lines, injector seals, misc gaskets.
Basically anything rubber is suspect.
and should be replaced

 

Whats a good way to check if my IACV is failing. Also what is a good way to check for vacuum leaks. I remember something about spraying brake cleaner or carb cleaner on vacuum lines and when the solvent hits a leaky line the engine will idle faster, something like that. Is this true?

 

if you can use propane to check for vaccum leaks.
the idle will rev up when the propane gets near the vaccum leak.

 

did you ever figure out what caused the car to vibrate while stopped in drive?
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