CIS w/Lambda Innovative Approach???

[fireant911]

I finally built my apparatus that will permit going from closed loop with the Lambda computer to open loop from the driver's seat with simply a 'flip of a switch'. I installed the unit today and was watching the results on my A/F monitor and have a couple of questions on what I had witnesssed.

While in closed loop (Oxygen Sensor connected to Lambda), during normal cruising, the car 'mostly' maintains 14.7 on the Westach A/F meter - some swinging of the needle is occuring which signifies that the Lambda brain is doing its job. Once I switched to open loop (which essentially disconnects the Oxygen Sensor from the circuit though I still have the ability to directly read the A/F reading) I am seeing a steady reading in the neighborhood of 12.2 during the same cruise speed. The basic mixture was adjusted with the Oxygen Sensor disconnected from the circuit and was set around 14.4 on the A/F monitor while the engine was fully warmed up and idling at 950 rpm's (I cannot afford the proper gas analyzer at this time).

1.) Is this proper behavior or does the mixture seem a bit rich when the Oxygen Sensor is disconnected from the loop? I thought that I have read here several times that an A/F ratio in the neighborhood of 13.5 was ideal when the Oxygen Sensor was disconnected.

2.) Can the CIS have the ability, with only one basic mixture adjustment, to both run properly with the Lambda computer and then run in the open loop mode (which essentially should be better with the more rich mixture / slight increase in performance / run a little bit cooler)?

The reason for my project and my questions is that so many folks here on this board strongly advocate disconnecting the Oxygen Sensor - I guess that I am hoping to "have my cake and eat it too".

[epbrown]

Originally posted by fireant911


2.) Can the CIS have the ability, with only one basic mixture adjustment, to both run properly with the Lambda computer and then run in the open loop mode (which essentially should be better with the more rich mixture / slight increase in performance / run a little bit cooler)?

It sounds like you want the car to run like the O2 sensor doesn't work while leaving it in. If it runs the same mixture with or without, why leave it in? Once you've got your mixture tuned properly without it attached, why bother? I'm a novice at CIS, so I'm seriously asking; I disconnected mine last year while troubleshooting some CIS issues and I've never looked back. You've gotten me wondering if I left something on the table.

Emanuel

[Paulporsche]

I would think that having a dual setup as you propose would be good

1. Use it in O2 mode for emissions testing and greate fuel economy
2. Use it in non lambda mode for extra hp, say on track days

I think you should use a WUR w/vacuum ports so you can get extra enrichment on start/warmup and WOT

[fireant911]

Paul,
You nailed my intentions exactly on the head. I realize that what I am wanting to do can easily be achieved by opening up the engine lid and either connecting or disconnecting the Oxygen Sensor though my desire is to have it be controllable from my driver's seat while I am traveling down the road. The unit I built works great but I am simply curious about the A/F readings I recorded when the Oxygen Sensor was not feeding readings to the Lambda computer.

[stlrj]

Why not run it at 12.2/1 and see if you notice your oil temps run cooler and engine more powerfull.

[fireant911]

Running at 12.2 A/F should decrease the temperature; however, my goal is to have the ability to shift from closed loop to open loop on the fly. I know from previous experiences with my car that open loop will give me 17.4 mpg and closed loop yields 21.5 mpg. I would much prefer to be economical when simply using the car to get from point 'A' to point 'B' and when I wish to 'truly drive' the car it would be desirable to have that extra kick immediately.

[john walker's workshop]

sounds reasonable. it's just the light surging from the oxy sensor doing it's thing that annoys me.