You may have a problem with the idle air control valve (IACV). Here's a test procedure:
Thanks! Vacuum is correct. Fuel pressure just a lb or two higher than what you posted. May be my gauge. Ground at engine is correct. Added the 44K and filled the tank with premium gas. I plan on a Compression Test and then I'll either swap the Injectors or just replace that one. I'm concerned about driving it for a week though to allow the Injector Cleaner to work since everything I read says it's very bad for the engine to drive with a misfire. Confused since I used to run engines with a misfire before. Just not a 4cyl Nissan.Several things that could cause your misfire:
- Dirty fuel injector. Run some good injection cleaner, like BG products 44K, through the system; give the cleaner about a week or two to do it's job. You can try swapping the #4 injector with another one to see if the DTC follows the suspected injector in it's new location.
- Incorrect fuel pressure. Tee-in a temporary fuel pressure gauge between the fuel feed hose and the fuel rail. The readings at idle should be as follows:
- with vacuum hose connected to the fuel pressure regulator: 34 psi.
- with vacuum hose disconnected from the fuel pressure regulator: 43 psi.
- There may be a major intake system vacuum leak. To check the intake system for a vacuum leak, attach a vacuum gauge to a full vacuum source. With the engine fully warmed up, the reading at idle should be 18 - 20 InHg. At 3,000 RPM, it should be 21 InHg. If readings are under 18 InHg, check the intake manifold nuts to make sure they are tight. The gasket may have failed; spray a water mist at the gasket to see if the gauge reading changes. Also check the intake plenum bellows at the throttle valve and at the MAF for cracks or loose clamps.
- Check your engine ground. With the car running, put a voltmeter on the lowest scale and measure from the block to the negative battery post. It should read no more than 50 millivolts (0.05V).
Thanks. I'm under the impression those injectors are easy to change on the rail as mounted on the engine. Saw a video, twist and pull.Considering the age of the car and the labor involved to replace just one injector, it would make more sense to replace all the injectors at the same time. it'll be fairly safe for the engine to run it for about a week or so with a misfire. Fuel pressure being one or two pounds off is OK.
www.gbreman.com is a good brand for replacement injectors. I use them on a regular basis with no problems at all. You can buy them from www.rockauto.com
The wrong place? They're in the same place as the one I removed and the same as those on the Rockauto site as far as I can tell. The biggest difference to me is the tip is longer. I transferred the o rings in that photo and actually installed the new longer one. It runs. Please look closer.No, the O-rings are in the wrong place. Get this one from rockauto: