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3 simple MegaSquirt questions
02GF74 - 12/11/07 at 11:57 AM

1. Can someone confirm that Megasquirt can run without lambda (oxygen sensor)? (know as open loop?).

2. So in this set up, the tweaking is more guess work as opposed to MS optimising it using the signal from the sensor (closed loop).

3. Will a lambda (oxygen sensor) be damaged by lead replacement additive, the stuff in the Castol bottles?

MikeRJ - 12/11/07 at 12:15 PM

quote:
Originally posted by 02GF74
1. Can someone confirm that Megasquirt can run without lambda (oxygen sensor)? (know as open loop?).


Yes. Many people only use a wideband lambda sensor for mapping, and remove it once done.

quote:

2. So in this set up, the tweaking is more guess work as opposed to MS optimising it using the signal from the sensor (closed loop).


Total guess work. I'd go so far as to say you will never get it mapped properly without one.

quote:

3. Will a lambda (oxygen sensor) be damaged by lead replacement additive, the stuff in the Castol bottles?


Yes, they contain phosphorous which does contaminate oxygen sensors.

paulf - 12/11/07 at 12:36 PM

1 yes it will work ok.

2 it is guess work and will be nearly impossible to map correctly.

3 I had the same problemm when I ran a crossflow and was concerned about it .I bought a couple of sensors from the scrapyard for a fiver and tested them , they were both ok so fitted one and ran it using lead replacement additives.
I used to use millers VSP which the manufactures told me was ok for O2 sensor use and had no problems.I then changed to Castrol which was not said to be safe for the sensor but still had no problems with it.
The millers product is manganese based and from what i could find on the web is better for Lambda sensors than phosphorous or sodium based additives .
I would think that if you do a limited mileage then you may get away with it and narrow band sensors are cheap anyway.I also found that widebands can be used with lead but have a limited life of about 50 hours when in contact with lead products.
The best way would be to fillup with unleaded and fit a sensor to tune the car , then remove it and run open loop whilst using leaded fuel which was my method at first but as i mentioned i eventually left the sensor in and it still worked ok.
Paul.