During any other day the car runs great. Just during rain or snow that it runs rough, almost like running on 4 cyl. It does not happen when driving on water or through deep water, just rain or snow. It sometimes smooths out again after driving for a while. I imagine it is a sensor but does anyone know which one?

 

need more info..start testing electrical sensors.. if it only happens in cold/rain conditions it is prolly electrical... check ignition system, see after a rain if water is getting under the hood etc etc etc...

 

if it's a VG then I would blame wires/cap

 

With the info provided, I would say, cracked distributor cap...

 

If it is raining or snowing, I start the car after having it sit for awhile, it will instantly run rough. Like I said on a non rainy day even if there is massive water puddles I drive through, the car runs perfectly fine. There is no way a distributor or wires can get wet if there is no water near it. It seems to somehow detect the moisture in the air. That is why I thought it was it was a sensor. It is a GXE model and a 91.

 

No, there is no way anything can get wet with no water near it but, when it rains, it normally raises the humidity in the air. Your engine compartment is not immune to this humidity. The reason you're probably not noticing anything while driving through puddles is, (splash guards) it didn't splash on the distributor. But, a distibutor-cap with a crack in it will let in humidity. Then if the temperature changes, that humidity turns into condensation inside the cap. I speak from experience; my father had an old 1991 Camry that did the EXACT same thing...

 

The only sensor that deals w/ humid air would be the MAF, but still it sounds like it is ignition.

 

Do you have a custom intake?
I have a cold air intake and my filter is only 1 inch or so above the splash guard. It turns out cheap ebay filters tend to rust away, so I had water reaching the MAF and causing a rough idle or stall.

 

this this this..+1

 

I will remove the distributor cap in the morning and inspect it for cracks or wear. I did not mean to sound harsh before but my tire blew driving over a massive water covered pothole and then my donut blew a few minutes later and I was a little irate to say the least but i'm better now and just want to thank all who responded with great possible solutions.

 

when its cloudy or raining theres low air pressure thus sensors should be able to sense this and equals out air/fuel ratio but could be one of ur sensors....check the dist and wires then clean the maf with maf cleaner and see if it fixes ur prob...or try using higher octane gas wen its raining or snowing and see wat happens...

 

first: seriously, check the stuff above.

my quick story: I had similar issues,when I first got my car from my sister; would bog down really bad, when wet outside (got it in early fall, so it wasnt cold). changed the cap/rotor, wires, plugs (needed doing, anyway) even threw some Heet in the tank, to no avail. changed the oil (yes, that is all I did that day)... and I haven't had that problem since... I don't know why, but it helped. and it was done on schedule (dad had previously done the oil change, since my sister is a blondie)

 

I got another one better: blew my tire by hitting a pothole.
changed to the spare (after about 20 minutes cussing, swearing and threatening God, and the lady walking her chihuahua over the way my wheels won't accept my lug wrench, and calling work, saying I would be late). got in my car, drove ten feet and my spare blew. fawking valve stem blew clean off the wheel.
I then proceeded to call in dead to work....
fortunately, for me, I was only about a mile from my parents house, so I walked there, got the truck, and proceeded to get new tires.

 

i have a problem with my 1991 nissan maxima it runs like crap in the rain i replaced the wires cap rotors and air filter and still runs like crap please help

 

check over your wiring. does it run like crap as soon as you start it when its raining out, or only once you get rolling and water being flung up into the engine bay perhaps and getting into electrical connectors?

 

More specific please..We need details...just how is it running? we need words that describe the running condition you are experiencing, otherwise we can't help you..

 

i had this problem also.. it started speratically then almost ona daily basis then i baught a new distributer/cap plug wires and mass air flow sensor in the intake. The kind of missing sound will on a rare occasion come back but it seems after i have washed the car or it rained but it will go away fast.....who knows what the deal is ive never officially determined the cause

 

One or both of 2 things...either your injector harnesses have some corrosion or a loose connection, or you have a intermittently failing injector..

 

yea that was the finel step was to swap my injectors but ive been running lucas injector cleaner through it and z-max just trying to clean them up and it has worked pretty well it runs very well and strong through the powerband its jsut that rare occasion it will want to miss

 

are you sure the dist cap is sealing to the distributor?