ECU Mystery

[glester]

I just wanted to relay a story you might find interesting. First, my vehicle. It's a 1998 Toyota Corolla LE, 4-spd auto, with close to 200K on the clock. Back in October 2008, I had a hydrogen boost system installed by a guy in Glens Falls, NY. I've been generally happy with the system, but I have had continuing problems with the ECU occasionally losing fuel trims. The system requires the upstream O2 sensor to be disconnected. The A/F ratio is controlled by a 50K pot wired into the signal line between the MAP sensor and the ECU. I do not have an EFIE installed on my car. I have been driving with the CE light on all the time, and scan gauge showing open loop operation. Several weeks ago, my car died as I was getting off the highway. I barely made it off to the side of the road. Long story short. I had it towed to a garage. Most of them are not knowledgeable with these HHO systems. The mechanic saw what I had in there and I had to explain it all to him. Well, what he did was reset the ECU and restored the MAP wiring to factory original. Since it was due for its annual spring tuneup, I told him to go ahead and do that. He never reconnected the O2 sensor. Here's the thing. No complaints here : The car is running great!! My tank averages are getting close to 38 mpg now that the warm weather has arrived. On flat straight stretches of highway at 55 mph, I am getting 55 miles per gallon! Scangauge shows the car in closed loop operation, and when I sent a command to the ECU to query the emissions status, no issues were reported! There are no trouble codes and the CE light remains out!! I don't know how this is possible. All I know is that it works and I will not screw with it. Just wanted to get that out there. If anyone has any ideas how a vehicle can run closed loop with a major emission control component disconnected, I would be interested to read about it.:):)