Rough idle at start up.

I have a 2001 nissan with the exact same problem and no one has figured it out yet either any suggestions would be helpfull

This question or concern I have is that on my 2003 Nissan Sentra 2.5L. Its idles hard and rough at red lights. I have had spark plugs replace. But not he wires. Still the same idling issue. A mechanic told me to replace my existing sysytem to clear up engine breathing, He said the idling is from the engine trying to push out to much air through exhaust pipes that are clogged or too small for the enigine. Also I recently noticed that When accelerating from a stop I can hear a low rumble. Like the sound of an after market muffler or exhaust tip. What could possible be wrong the car and what should I do to correct the issues?

No light has come on yet. I took to the one shop and the guy there said I needed to free up my exhaust. (Saying it was clog or the exhaust pipe wasnt wide enough for the air passing through. I am curious to know if it is the INTAKE GASKET. At the shop they never did and computer code check. Would something pop up if they did that?

All lights come on and shut off once I start the car. The idling is only present when I am at a red light and the car is in DRIVE. The car smooths out once I put the car in park or neutral or reverse (sometimes). I did check my air to see if it was loose or not bolt on properly. I have an appointment wed at Kal-tire to raise the car on hoist to check the exhaust pipes and such.

P.S. - All your suggestions and your opinions are very much appreciated. I only know a little bit and about cars.

Once putting the car in neutral it smooths out. Once back in drive and motionless the car will start idling rough again. Once back in drive and moving the roughness goes away.

Helped friend change the head gasket on his sentra after the car overheated. Changed the head gasket, water pump, and thermostat. When we put the head back on and got everything else hooked up the we started the car and it sounded bad. Had a very rough idle and was idling at about 600 rpm. We concluded that the timing was off. We took off the valve cover and sure enough our timing was off. We took the timing chain off the cam sprockets, put the cams in time according to the mating marks on the sprockets, put the crank at TDC on 1, then put the chain back on the cam sprockets, valve cover back on and so forth. From the mating marks on the crank and cam sprockets it is timed perfect. We start the car up and it idles high at 1200 rpm, the starts to slow down to around 700rpm. Its rough and shakes alot. However you give the car a little gas and the engine sounds great, fires on all four, and there is no shaking, just smooth running, let off the gas and the rough idle shaking starts. I have three theories, the EGR is not working right, I have a vacuum leak, or the IAC is not working right. Need some help here please on diagnosis. Oh yeah prior the head gasket change, we had just replaced the plugs, wires, and the fuel pressure regulator.

I have the same problem with my 2000 sentra.

We figured out what was wrong. We didn't change the rubber gromets on the underside of the valve cover that sit on top of the spark plug holes and oil was getting causing the plugs to get wet. They changed the ruber gasket/gromet and put knew plugs in and it ran alot better but the timing was off just a little. So my buddy had some other dude go over there and he jumped the timnig the wrong direction and hasn't been back to help him. The chain is supposed to have two blue marks and one pink one on it. There is only one mark, factor defect I guess. So all we need to know is how many chain links should the chain have on top when the cams and the crank are set at TDC so we can know how much slack to leave or take out when putting the chains back on the sprockets since we are missing two of the marks that should be on the chain.

What would cause a car to have a rough idle at a stop only when it is in gear?

Just replaced it and it wasnt the problem I have had the problem for a while and I have replaced a few things and just got the head gasket replaced with new timing chains and everything for timing

I have a 2002 Nissan Sentra GXE 1.8L with 16,600 miles. Car was driven by an older gentleman that passed away. Car sat for approximately 1 year (may have been moved occasionally). Bought a few months ago and have put 3,600 miles on it without any problems. Drove car a couple days ago for one hour at highway speeds. When I came to a stop, the idle started running very rough. The rough idle started all of a sudden, it did not get progressively worse over time. With the car in drive, the idle hunts constantly between 600 and 1000 rpm. With the car in park or neutral, the idle holds around 750 rpm, but is still a little rough. The car comes very close to stalling while in drive all the time, but has only actually stalled once. The check engine light has not come on and I do not have any stored codes. The car starts right up when it is cold, but it starts hard when it is hot. I usually have to press the gas pedal to get it to start when it is hot. The idle seems to work the same whether the car is hot or cold except that it starts out around 1100 rpm and quickly slows down to a rough idle at 750 in park when it is cold. I have seen it sometimes hunt for a little while and then settle down at 750 rpm when the car is hot and in park when it is first started. The car still drives very well at any speed above idle and the acceleration is good.

I tried cleaning the MAF and throttle body without any change (used the correct cleaners). Both the MAF and throttle body looked very clean before I cleaned them. I replaced the air filter when I bought the car and it looks good. I visually checked the vacuum hoses. I did not find any leaks. I pulled the PCV valve and it seemed to be working (rattles), but I cleaned it anyway. I checked the spark plugs and they all look good. I performed the idle air volume learning procedure without any change. I know there is a TSB for my model year car saying to replace the EGR if you have a rough idle, but it says it only applies to cars built later than mine (after 2/02 mine was built in 8/01). The service manual says to verify there is gap between the throttle drum and throttle opener rod at idle. It does not specify that the engine has to be cold when checking. When my car is cold, the rod pulls back and there is a gap. When the car is hot, the rod does not pull back and there is no gap. I verified there is a vacuum going to the throttle opener rod (hot and cold). The manual says to replace the throttle body if there is no gap, but it idles rough even when there is a gap. Does this test only apply when the car is cold?

Since the car is hard to start when it is hot, can I rule out the EGR and MAF? I do not have the tools to check for fuel pressure. Can I rule out fuel pressure since the car runs well at any speed above idle? Any help would be greatly appreciated.