Tuning only to an EGT gauge can be very misleading, but also, can be very helpful, providing you know what to look for, and have the proper system running the engine to tune it. With just the SFMU setup, you at the mercy of the stock ECU for ignition timing, which is VERY important also, but nobody ever mentions it. Hot EGT's don't necessarily mean running to lean or rich. Not running enough timing advance under boost can make for REALLY hot EGT's, and a fast rising EGT. Combustion is taking place too late in the engine cycle, and the flame front is still burning, partially out the exhaust valve and into your EGT probe. Case in point here, from personal experience:

Using the Megasquirt for fuel AND timing control, i set A/F to around 12.4:1 at 10 psi boost. Ignition timing was around 22-23 degrees advance. Top of 4th gear at 10 psi, EGT's were sitting steady at 1550 degrees aprox, and not going any higher. This is a *good* state of tune for that boost pressure. Now, with the stock ECU doing ignition, timing advance is roughly around 17 degrees, at ANY boost pressure,with no good way to get more timing(playing with the MAP signal can help, but only if you run the MS for fuel). So with the stock ECU at 17 degrees, and the A/F the SAME at 12.4:1 at 10 psi, EGT's RISE FAST up to 1600 in 4th gear, way before i can even get through all of the gear.

This goes to show that tuning to EGT only, is not the best way to do it. Since with the SFMU we are at the mercy of the stock ECU for timing, we have to run richer than that *perfect* tune, in order to keep the EGT reasonable(and also not making the power we should be). I hear a lot of people say that running too rich can cause hight EGT, but i've run this motor in the 10:1 A/F range before, and EGT's were cold as hell with all that fuel. Too little timing will cause a high EGT over too rich A/F any day. To sum it up, too little timing, or too little fuel will give you a high EGT, and fast climbing EGT. Hopefully this clears things up a bit with boosted tuning.

13.5 @108 MPH-2.2 60ft(stupid FWD!)
S16G @ 18 PSI/FMIC/Running on MegaSquirt II (Now with sequential
fuel injection)
My webpage: http://eclipsed4evr.home.comcast.net
-1998 Mitsubishi Eclipse RS-T- "Toy"
-1992 Plymouth Laser Turbo AWD(SOLD)
-2000 Honda CR-V(daily)