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wild lambda reading on MSnSE - why?
Steve Lovelock - 31/12/08 at 01:14 PM

Hello, I am running a MSnSE on a Redtop Vauxhall engine using GSXR TBs.

I have been using MLV to automatically tune the VE table with some success. However I noticed that the table was getting richer and richer and hence fuel economy was getting really bad. So I started trying to understand what the various variables were up to so that I could get a better set up. Then my LC1 broke and I stopped working on it. Now I am back to the tuning with a new LC1 wideband but have notice that the AFR value varies in a peculiar way. The AFR reading is either maximum at 21 or minimum at 7. The value flips from one to the other and then back again. It never stabilises. Any ideas why or what I can check to sort it?

stevebubs - 31/12/08 at 01:16 PM

have you got the output set as narrowband?

Steve Lovelock - 31/12/08 at 02:13 PM

Output from where?

I had previously looked at this and checked that the settings were all for the LC1 but am not sure that I have it entirely correct.

stevebubs - 31/12/08 at 03:18 PM

IIRC you have to program the outputs of the LC-1 to go 0-5v wideband, and the Megasquirt to accept this input.

By default I think one of the LC-1 outputs is set to narrowband...

stevebubs - 31/12/08 at 03:22 PM

http://www.innovatemotorsports.com/support/quickstart/LC-1_Quickstart.p df

quote:

The default analog outputs are as follows: Analog output one (yellow) is 1.1V = 14 AFR and .1V = 15 AFR. This is a simulated narrowband signal. Analog output two (brown) is setup as 0V = 7.35 AFR and 5V = 22.39 AFR.

flak monkey - 31/12/08 at 03:22 PM

The LC-1 has 2 outputs, one is narrowband and one is wideband. Both can be programmed to give readings to suit the application. You need to check you are using the wideband output, and that it is set to read 10:1 @ 0v and 20:1 @ 5v and also set the MS to the same setting in the configurator (File>Configure>Car1>Settings etc)

Also check that your grounds for the MS and LC-1 are very good. Also have you got a 6 or 7 wire LC1? The 7 wire has its own ground for the output which needs to be connected to the main chassis ground and the MS box.

David

stevebubs - 31/12/08 at 03:23 PM

Loads of info here

http://www.diyautotune.com/faq/faq.htm

mark chandler - 31/12/08 at 04:26 PM

Also setting wideband in megatune is not enough, you need to go to file>configurator and select LC1 here also.

Regards Mark