MSefi.com read only forum (Jan.15,2018)

I just came back from a 2 X 9 hour drive in mt VW van with MS II and an LC-1 with wB O2 sensor. On the way home the old aircooled engine got pretty hot coming up a long pass. I was in second gear for a good 15 minutes at WOT. All is well until a minute or so over the top of the pass and shooting down the other side. I discover I have no power from the engine, only gravity pulling me downhil but the engine will idle. I get stopped at the bottom with the engine idling fine but doing nothing when I hit the throttle. I intuited a problem with the O2 sensor. I cracked open the laptop and megatune and discovered I was right; the O2 sensor stuck on about 10:1. I disabled EGO control and asked my wife to stab the throttle. Vroom, vroom, and we were off like a herd of turtles again, running open loop on the VE table for the next 400 km home.

My point is (and I do have one); if I had not had the laptop available to disable the EGO control I would have been screwed. Is it possible currently to have EGO control fail-over to VE map control if the O2 signal fails? If not could this be implemented in a future release? Thank-you very much.

GG

p.s. I had a look at it last night and the LC-1/O2 was working again once I enabled it. I surmise that I temporarily cooked the LC-1 controller since it was in the very hot engine compartment. I now relocated it to a much cooler area, but I will always be a bit suspicious of its reliability.

If I understand your inference correctly, if the sensor fails completely (controller dies or sesor itself malfunctions), the megasquirt will function directly off the VE table even though the EGO correction is still enabled? In my case I did have the EGO authority at a high level (40%), but it seemed to me at the time that I must disable EGO control in order for Megasquirt to ignore the dead sensor/controller.

GG

I have my LC-1 configured to output 2.5v or 14.7:1 during warmup and in case of fault. For me this effectively shuts off EGO if there is a fault. My AFR table is pretty much 14.7:1 throughout. I to am a little suspicious about the long term reliability of the LC-1.

On the other hand I had a vacuum leak once that blew the VE table straight to heck. I put EGO to 100% and she drove surprisingly well until I could fix the leak. (I.e. all EGO and really not using the VE table at all)

oughtsix wrote:I have my LC-1 configured to output 2.5v or 14.7:1 during warmup and in case of fault.

Can you explain this please? How do you do this in megatune? Thanks,

GG

gundesen wrote:

oughtsix wrote:I have my LC-1 configured to output 2.5v or 14.7:1 during warmup and in case of fault.

Can you explain this please? How do you do this in megatune? Thanks,

GG

You can't. You need to use the application from Innovate; Logworks I think it is.

I don't use EGO correction at all though. Once you have a good tune you can run open loop just fine. To me the O2 sensor is just a tuning aid.

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