Engine Mechanical problem
1991 Nissan 240SX 4 cyl Two Wheel Drive Automatic 190000 miles
I recently replaced all 4 fuel injectors on my 240SX (4 cyl w/double overhead cam).
1) after installing re-built injectors, upon start up, billowing grey smoke. Before replacing the injectors I tried to de-carbonize using cleaner through a vacuum tube, so I thought it was left over cleaner. After about a mile, the smoke cleared up and I drove it about 5 miles. Ran great.
2) about an hour later, next start up, flooded. Eventually started, drove about 5 miles, lost power to the point where I could not go over 50 mph. Took next exit to get home after about 2 miles. It stalled at the end of the ramp and could not start. Towed home.
3) pulled injectors. The lower o-rings were damaged. I had lubricated them with oil when I put them in, but did not use silicone. Probably it. Heavy gasoline smell in the oil. Changed the oil which was very diluted with gas. Maybe 1 or 2 quarts.
4) replaced o-rings on new injectors, plenty of lube, they went in very smoothly. Idled great, after the engine was under load, more grey smoke. Pulled injectors and o-rings were intact.
6) reinstalled the old injectors to get back to a baseline. Lubed properly and they went in smooth, same smoke once engine put under load. That really puzzled me.
7) pulled the spark plugs. There is a fine layer of dry carbon covering them. No oil at all. All 4 looked exactly the same. Plugs were put in new with injectors. Now I am really puzzled.
Checked water, OK. Don't think it is a head gasket. Tailpipe is wet, but does not smell like oil or antifreeze. Smoke is not black or white, just grey and smells fuel rich. Plenty of exhaust pressure, so I think converter is ruled out, maybe. Perhaps the damage to the o-rings allowed so much unburned fuel to pass through the exhaust that either the converter is fouled, or the O2 sensor is fouled, causing an extremely rich condition. I cannot tell because the car will not work with my OBDII code reader. I guess it could be another fuel component, but I wouldn't think it would fail at the exact moment I replaced the injectors. Also, if it were rings, I would think the plugs be oil fouled and most likely they wouldn't all be coated so evenly. No oil back to the air filter, so I think the PVC valve is OK. Something must be telling the fuel system to dump fuel, or maybe I am not getting the injectors sealed properly. They feel like they are in there pretty good and I am almost certain that they are going in without damaging the o-rings. Also, I didn't see any damage to the sides of the fuel rrail. I was very careful getting them out. Any thoughts are much appreciated.
Monday, August 11th, 2008 AT 9:26 PM