# Rough idle in the cold



## eddy_75165 (Jun 22, 2005)

Hello everyone,

Everytime I have used this I have recieved great advice, so here we go again.

My 4 cylinder, manual transmission, 97' Nissan XE Pick-up w/ 150,000 miles started to have a rough idle a few weeks back. It was acting as if it were going to die but it just idles eratically and rough...anywhere from 300 to 800 RPM instead of the normal of around 1000 RPM. In addition it will act as if it is missing a little unless I keep the RPMs up while driving, and as long as I keep the RPMs up it is like normal. If I lug the engine even slightly, it sarts to act like it's missing again. It also goes back to the rough idle when I depress the clutch to slow down. What's more confusing is when I crank it in the morning in my warm garage (I live in North Dakota) it runs fine. It doesn't start the rough idling until I'm a few miles down the road. Maybe the cold is not helping matters. 

So I bought a Hanes repair book and it told me that it was probably either the PCV valve or the EGR valve.

Well I checked all of the obvious things and replaced my air and fuel filter and PCV filter, but I can't find my PCV valve, although I can feel some suction on the hose that goes into the valve cover from the air cleaner. So I don't suspect the PCV valve, but I still want to replace it since I never have.

SOOOOO...... 1. Can anyone tell me where my PCV valve is located?
2. Any ideas before I buy the $100+ EGR valve?

Thanks,
Jason


----------



## Smith1000 (Dec 29, 2005)

Might not be the pcv valve or egr if it starts and runs okay when it is in the warm garage. This is just and idea, but maybe look real close for any loose or broken vacuum lines. I have an 89 pickup and was experiencing a similar problem at the beginning of the winter. I was able to bump up the idle to keep it running. It has throttle body fuel injection. Later I looked real close and found a broken vacuum line. When I reattached it, I had a very high idle. Had to adjust it down then. 

Another thing: Have the plug wires been replaced recently? Are they all on tight? Any codes all?


----------



## eddy_75165 (Jun 22, 2005)

I looked for vacuum leaks and didn't find anything, in fact everything looked really good, but I'm not against taking another look.

I keep my vehicles in otherwise good shape. So yes, it does have fresh plugs, wires, distributor cap and rotor. I will recheck their tightness.

What do you mean by any codes? I haven't paid to have a diagnostics yet. I wanted to try this forum before I go to a shop and start to spend money.

Thanks,
Jason


----------



## Smith1000 (Dec 29, 2005)

Has the check engine light been on at all since you have been having this problem? If so, there might be a code stored that will give some indication of the problem. I use and OBD II code reader on some of our vehicles (Buicks). Also have a 95 Pathfinder. The 89 Nissan is a farm truck. Have had the Pathfinder for 6 or 7 years and have never had a problem with the engine-not one check engine light. Some of the Auto parts stores around here will read/check codes for free. 

How is the gas mileage? If it were a vacuum leak, mileage would probably be dropping some.


----------



## eddy_75165 (Jun 22, 2005)

No check engine light. The gas mileage has been steady.

Do you know how I can find out where the PCV valve is?


----------



## Humanure (Feb 15, 2007)

eddy, this link will tell you where to find the PCV valve: http://www.nissanforums.com/hb-truc...e-cover-gasket.html?highlight=pcv#post1139788


----------



## Chick Marmelade (Dec 22, 2004)

Hey eddy,

I had a similar problem on my '94 4x2 when it had about 40,000 miles. Turns out the gasket on the intake manifold came apart where one of the injectors goes into/through it. The injectors are at the top of the intake manifold and the gasket has semi-circular humps to go around the injectors. Don't know how it could have happened, but the gasket ripped and flipped up around the first injector causing quite a vacuum leak. It would start but run really rough except at speed when it was warmed up, and alway run rough at idle. I'd look really carefully around the intake manifold to see if the gasket blew up.

Chick


----------



## xero69 (Jan 24, 2007)

Jason (eddy_75165) my truck is same as yours and is doing the exact same thing. Before I go throwing money at it I was wondering if you had solved your problem and if so how. Thanks!


----------

