glester
04-21-2010, 07:33 AM
Hi everybody. I confess to being an infrequent contributor. I'm not much into posting unless someone brings up a question I can speak to intelligently. Today I am looking for some input on a problem I can't get my head around. My vehicle is a 1998 Toyota Corolla LE, 1.8 litre, 4 speed auto. In October of 2008, I had a hydrogen boost system professionally installed in this car, as gas prices at the time were heading for the $4.00 per gallon mark. I have been very happy with the system, and still am. The requirements of making this system work correctly include removing the upstream O2 sensor and installing a 50Kohm pot in the signal line between the MAP sensor and the ECU, so the air/fuel ratio can be adjusted manually. I have gotten used to the "check engine" light being on all the time, as the typical gains I have seen with hydrogen boost have been 20 to 25%. There have been a couple of occasions where the car's ECU lost its mind and the fuel trims went way out of whack. However, two days ago, on my commute into work, I rolled off the interstate and stopped at the red light at the end of my exit ramp. When I went to apply the accelerator, the car just didn't want to move. It would sputter and stumble. I managed to get it off the road. First thing I did was to get into my Scangauge and look for any new codes besides the two that I expected to find in there relating to the O2 sensor. To my surprise, I found NO codes at all. The Scangauge also showed the car to be in closed loop operation! With a disconnected O2 sensor??!! The car was due for its annual tune up, so I had it towed to the Toyota dealer. They tuned the car up and changed the oil. The car is running well now, but it's too soon to get a handle on my gas mileage, since scangauge was disconnected when Toyota techs ran their own diagnostics. My gas gauge shows slightly less than half a tank with 245 miles on the trip meter, which is good. I guess my question is this : What happened to the O2 sensor codes? The O2 sensor is still disconnected, yet the check engine light remains out. I'm baffled by all this. Any similar experiences??:confused: