Rough running at idle

DIRTMANDAVE

MEMBER
1993 NISSAN ALTIMA
23,000 MILES

Runs rough at idle and cruising. If you nail it is smoother than silk with all power. I have changed wires, plugs, egr, fuel filter, fuel pressure is in specs, in other words a complete tuneup. It ran great before the tuneup but turned over for 5 seconds before it would start. I pulled the plug wires with it running and 2, 3 and 4 showed a change at idle. Ok, then I pulled the plug in #1 and turned the engine over and had plenty of spark. Could the injector be plugged at idle but work fine when you really take off or just speed up on the road? Any help muchly appreciated. This car is actually mint condition in and out even with the miles on it - it looks brand new! Oh yes, the cat converter has been cleaned out so there is no restriction in the exhaust

1 Reply

DRCRANKNWRENCH

MECHANIC
3,380 POSTS

I would run two cans of high quality fuel system cleaner through it.
BG44K is the only fuel system cleaner that really works. You will have to go to a car dealership and get it from the parts department. It is around $20 a can. You will run a can on a full tank and expect some strange things to happen as deposits are removed. Once the two cans and two tanks of gas, are run through you will still experience some little things as the computer catches up and depsosits are blown out or end up in the oil. When you run the third tank out you will see a noticeable difference and the injectors will be clean. If you have issues stilll then something else is wrong, but you need to do this anyway as since you have low mileage the car has sat and the probablity that the injectors are cloged with old gas is very high.
So, you won't loose out by doing this. Also, it is a good idea to change your oil after the thrid tank of gas has been used up.