So, I'm actually doing pretty good with this thing...

http://www.fueleconomy.gov/FEG/noframes/519.shtml

Yup, original fuel economy information for the 1985 Grand Prix with the 5.0L V8 and a 3 speed.

15/20. I'm getting that when I don't have roasted plug wires. Hoo-ray for matching the factory with a bigger engine, bigger camshaft, and 3.73 gears out back. Go me.

#$@#% ignition!

So, last tank was a paltry 13.4mpg and it feels like the miss is back.

I go and inspect the plug wires. Two are burned up. TWO. These are supposed to be super-duper high-temp wires. Burned wires on on the passenger bank, so the O2 sensor didn't pick up on it.

Oh, and Edelbrock, your T.E.S. headers for G-bodies are SHIT. I'm sorry, but the passenger side header provides no way to get the damn plug wires to the distributor without running them dangerously close to the primaries. Technically, you owe me three sets of Accel Spiral-Core plug wires.

I've wrapped the burned up wires in electrical tape and tied them up against the valve cover. Hopefully they'll last until I can get some different headers. Wife's going to love this...

Andrew as a gerbil...

Save the Richard Gere jokes.  This was over at Icanhazcheeseburger.com.  Topical, I thought.

15.2 mpg!

Okay, so I got the timing control in the distributor. Prior to that, I had richened up the fuel map to get the car to run smoother, dropping my gas mileage into the low 14s and high 13s. After the first tankful using the computer-controlled timing, a tankful that included a lot of city driving, and lots of putting my lead foot into it trying to tune the upper parts of the fuel map, I'm back in the 15s.

I'm going to drive like a grandmother this tank and see if I can stretch it into the 16s. I've also reduced the authority on the closed-loop algorithm. While I was tuning the maps, I gave it 10% leeway in either direction, I've necked that down to just 5%. The swings are much reduced as seen on the wideband and in the datalogs, so hopefully that'll cut my fuel usage more.

Computer controlled timing!

Finally, I've done it. During that horrible UK/UL football game Sunday, I did the board modifications to allow me to run a computer-controlled distributor.

I then spent three nights, probably 9 hours total, fighting with what I thought were bad HEI modules and coils. Turns out the instructions for modding the megasquirt had me use a resister on the tach circuit that was way too high impedance. I replaced the resister and it started right up.

I ran it around the block yesterday afternoon, and it ran great. Idles better, miss at cruise is gone, and the car can pull all the way to 5000 rpm with no spark scatter. Then it died. After sitting on the side of the road for a few minutes, It started again. I'm guessing an overheated coil. I changed the poop coil I had been using during the troubleshooting out for my good coil and made the drive in to work this morning with nary a hiccup.

Now to find some time to get over to Autolab and use their dyno.