[mrturrari]

Here's an update:

That slightly lower voltage going from the SMT6 to the ECU was causing problems. It was actually causing AFRs to go to 17:1, 18:1 and even 19:1 during moderate loads especially between 2000 and 3000 rpms. This would sometimes cause a bit of detonation, felt as a loss of power and even a couple of times send the ECU into panic mode. It would die and then I would have to turn the ignition off and on again to start it. So for the last week I have had it bypassed to see what the ECU does normally.

I know people always say how rich the 5sfe runs but let me tell you the 93 5sfe is not that way at all. Realize that mine is highly modified but I am still running the stock cams for now so I think the same would be true for any 93+ 5sfe. Once the car is warmed up, during part throttle from 2000-3000 rpms it seems to be perfectly normal to see AFRs go to 15.5:1 all the way to 17:1. Because it's low load and low RPMs this is nothing harmful and not even noticeable. However when you add the voltage drop from this SMT6 of 1 to 2 tenths of a volt it moves that up a point or two and things start getting nasty.

The solution is pretty easy. The SMT6 has a setting under Global Parameter Setup called Fuel zero calibration. I just set this to 1 and the problems went away.

So for anyone who is installing an SMT6 I would recommend you check the voltage coming from your MAP sensor to the SMT6 and be sure it is the same as the voltage going from the SMT6 to the ECU. This is done at idle and with the fuel maps at zero after you have calibrated the load and rpm scales. If the voltages are very different then set the fuel zero calibration until they are as close as possible. The grainularity is not great, an increase or decrease of one moved the voltage by more then a tenth, but it should be enough to get it safe again.

I'm going to drive it around a few more days and see if it remains good. If it does then I am ready to either install an AFPR or put in some bigger injectors.