14.9mpg!

Yes, lower than the 15mpg I posted earlier, but there's a caveat:

That 15mpg was 60 miles of highway driving. This 14.9 is 191 miles of mixed city driving.

Also, updates to this blog will probably slow down again. At 6:45 am on June 17, my daughter, Wednesday Judith Huffman Scott, was born. She was 8 pounds, 6 ounces, and 19.5 inches long. A week later sees her back up to her birth weight and the whole family is doing quite well. She is sleeping well, eating well, and has proven to be a poop machine.

Refinement

Not being one to leave well enough alone, I set about trying to improve my erratic RPM signal. As you can see in this picture, the RPM (yellow plot, top graph) the Megasquirt has been reading has been really choppy. This can be due to lots of reasons, but the biggest is noise getting into the signal line.


After about 30 minutes of fiddling, a 10K ohm resister turned out to be the best at filtering out the noise without cutting off the signal entirely. You can see a huge difference in the graph below (again, yellow plot).

Fixed!

Finally, after nearly two years, the car runs properly!

In addition to the plugwire I saw shorting the other night, one plug wire was disconnected. The car has been running on six cylinders for a long time. The plug was fouled something terrible.

I got the new shorty plugs installed last night, got the new wires and looms installed, and drove the car to soccer with my stepson. It has power now, like it should. It runs smoothly, like it should. I was seeing some pretty high temperatures last night (205 degrees coolant and 165 degrees intake air). I hooked the vacuum advance back up this morning, and that solved that problem. Not enough timing at cruise generates a lot of heat.

Oh, I also fixed the sticking rear brake. I took the drum off and sanded the shoes and the inside of the drum, then doused it all in brake cleaner, and cleaned the drum with carb cleaner. It still smelled like gear oil, I guess the stuff managed to embed itself in the pores of the metal. If the squeal and sticking comes back, I'll have to get that drum turned down a couple thousandths.

I'm pretty happy right now.

Parts parts parts

Well, O'Reilly had everything. I got new plug wires, shorty header plugs, and a wire loom kit. $100, but it should hopefully end these recurring ignition problems, and hopefully bump the gas mileage a bit more. If it can get to 20mpg, these parts will pay for themselves quite rapidly.

Damnit!

Way back on March 15, 2007, I detailed a burned up spark plug end that was causing a miss.

Well, it's happened again. I bought schmancy new high-temp 8mm Accel wires, and have them in the little fiberglass socks, and I still managed to burn one up. Found it again tonight with the idling-car-in-the-dark trick.

So, tomorrow, I'm off to O'Reilly to pick up another set of plug wires and hopefully they can order me some shorty spark plugs to give me more header clearance. Their web site says they have them but they have to be ordered. I may call Street 'n Strip and see if they have them in stock or not. Hopefully they do.

I disconnected the vacuum advance, too. Feels a little better until it gets hot and that plug starts shorting.

It's a miracle the catalytic convertor hasn't taken a dump yet. I'm going to have to check the oil, too. Stupid car.

15mpg!!!

Woo-hoo! Drove sixy miles last night on four gallons of fuel. Yee-haw.

Finally, improvement.

13.2mpg

GODDAMNIT!

Runs much smoother with the timing fix. I'll check back in after I go through another tank.

Timing is everything

So, I'm almost through the first tank of gas since fixing all the fuel issues. I don't know the mileage yet as I haven't filled up, but it looks to be a bit higher than it was. I'm at 210 miles on the odometer with about a quarter tank left. After adjusting for the incorrect speedometer gear, that means ~175 miles on ~12 gallons, or 14.5 mpg. That's a vast improvement, nearly 50% over pre-fuel fix (10mpg).

Moving the bottleneck down to the next step in the ladder, I went outside today with my fancy timing light to check the timing. With the vacuum line off at idle, in gear, 12 degrees. Perfect. With the vacuum hooked up? 35. Oh snaps. Too high.

Rev the engine to around 2000rpm in neutral? FIFTY DEGREES of advance. That's way too much. I backed the vacuum advance off until it was 40 degrees at 2000rpm. That put it ~23 degrees at idle, and really smoothed things out a lot. We'll see how it drives on the way to work tomorrow.