tuning with LM 1 on my MFI 2.4 T
 

All,

I have been reading some of the threads where the LM 1 was used to tune both air flow ratio at idle and under load. Does anyone know what the ideal ratio's would be to shoot for both at idle and under load. I am assuming that the rpm at idle would be 950 and under load would be at 3,000.

I've been helped quite a bit on this site and have gotten my car running not badly at all but would like to really get it there. Using the LM 1 seems to quantify the end points to a tuned engine.

thanks

Hold it around lambda 1.0-0.95 at idle and light load and around 0.82-0.84 at WOT.

Of course, MFI being MFI it won't be possible so shoot for lambda 0.83 at WOT and make sure it doesn't go pig rich at idle and light throttle. That's probaby the nearest you can get by fiddling with old worn MFI w/o making custom space cam.

Mark,

The rule of thumb is 5-6-7-8-- five to six percent CO at idle and seven to eight at part load. Part load MUST be measured in gear with the car moving at 3000 rpm, and you always set part load first, THEN idle, as outlined in CMA.

Those settings make it run way rich but seem to be the magic numbers for drivability and the chainsaw-like throttle response of MFI. For example, 5.0% CO is about 12.6:1, whereas 8.0% CO is about 11.54.

OK, let's convert to Lambda for our friend from Sverige-- lambda * stoich value= AFR so 12.6/14.7 is .85 lambda.

LM 1 tuning MFI
 

Thanks a million guys, this clarifies everything.

As soon as it gets warmer up here in Toronto and I can get the car out of the garage (we've had 30 to 40 cm of snow over the last couple of days) I'll get going on this.