Anyone with LM-1 Gas Analizer Experience

Milton, If you remove the 02 sensor it will give you an inaccurate mixture reading because you have changed a parameter the ECU uses to set its injection pulse time there by giving you an incorrect reading for you to adjust to. The 02 sensor is the sensor the ECU uses to fine tune the mixture and then signals the injectors pulse time(lean or rich) at idle after full warm up of the engine, it is trying to keep the mixture at 14:7. Anyway if you remove it you will be in open loop mode and then you would be tuning to that OL situation. Then when you reconnect the 02 sensor you are changing the parameters and you are out of adjustment again ie; right back where you started. There should be somewhere on the exhaust that you could weld the extra fitting. On my 355 I installed them(2) near the existing 02 units. You also want to be as close to the source as possible. I also thought I should be as close to the factory position to duplicate the reading as best I could. Hope that helps. Regards, Vern

Edit: Milton it didn't dawn on me what kind of car you are adjusting until after a wrote the above, my frame of reference is based on the 2.7 motronic which is not what you are working on. Is your 02 sensor the single wire type? If so you are probably OK to remove the factory sensor and plug and play. Sorry for all of the above it may or may not apply. Regards, Vern

 

There are 2 correct procedures for the cis system according to Ferrari.
One is to disconnect the O2 (at that point it really doesn't matter if it is screwed in the pipe or not) and make an adjustment measuring up stream to the correct CO level, making sure the other gasses stay within limits.

The other and more common is to use a duty cycle meter hooked in line with the frequency valve and to adjust that to 50% at a hot 1000 RPM idle with everything hooked up.
If you dont have a duty cycle meter a dwell meter is the same thing with a different scale. 60 degree scale, 30 degrees = 50%.

CIS mixtures change quite a bit with RPM so make sure the idle speed is right.

I also ALWAYS retest after the O2 is reattached to be sure the 02 system is working correctly. At that time it should drop below .6% CO with a good balance of all the other gasses on a US car.

BTW Late 328's have an upstream analyzing tube built into the car. It's behind the R/R wheel sticking out to the side.

 

The dwell meter should show a sweep of about 10% of the range. That indicates normal functioning of the O2 in a K lambda system. No sweep but proper setting (50%) suggests that the sensor is not functioning at all and may just be unplugged. Pull the boot on the large green wire for the sensor back to expose the metal terminal to be sure it is connected. I have seen them inside the rubber but disconnected or taped off to fool a visual inspection when the o2 system was malfunctioning and no one wanted to repair it.