Tuning continued...

[christer.medin at lennoxintl.com]

Well, went for a ride yesterday while tuning the Haltech setup in my friend's car.  Since several people adviced bumping up the fuel a bit, we fattened up the maps a good bit before taking it for a drive... once we were on the road I checked the o2 voltages and adjusted the portions of the maps that were still too lean.  Ended up with o2 readings around 800-840mv consistently.  However, we still have a stumbling/misfire problem right around 3000 rpm (was at 2500 or so yesterday) that's definitely not a fuel issue.  We checked all the wires, and they measured fine, so we're going to pull the plugs tonight and see if running lean earlier may have damaged them.  The 3000 rpm stumble is peculiar though, it feels almost exactly like hitting the rev limiter.  The only thing I can think of that's related to that particular RPM (or close to) is that we have full advance dialed in right there.  Makes you wonder if something goes wrong right after the computer's done putting in all the advance, some type of software glitch or something.  Also didn't see the computer trim the fuel any at all, even when we enabled closed loop.  Seemed a little odd to me.
So, this evening (didn't get going until rather late last night, were out getting parts for a cold air setup for it) we'll pull/replace the plugs, and if that doesn't help, move the advance up/down a bit to see if the stumble follows it somehow... other than that, I don't have any ideas right now.  The fuel pressure holds steady all the way, by the way.  And, the car runs like a champ as long as you keep the revs down.

Christer