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.

15.4mpg

Some more tweaking on the map netted me another 0.5mpg. That's an additional 3%. I may be able to gain a bit more by tweaking the cold start stuff, I think I'm richer than I need to be under warmup. The priming pulse is also too long and is flooding the engine, so that's wasted gas as well.

In August the Street Rods are coming to town. Hopefully I can score a 3.42 or 3.08 ring and pinion for my rear end. That'll drop my cruising revs a bit and fix the speedometer.

I also need bigger fans. I've seen the coolant temp as high at 230 degrees on a 92 degree day sitting still in traffic.

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.

Progress? I think yes...

Verdicts after driving to work this morning:

1. No exhaust leaks when I started it, and it was colder this morning.
2. Thanks to the fixed exhaust leaks, the wideband was showing sane numbers
3. Valve tick is gone
4. I was crossing an AFR border on my target table on the way in to work today. I've raised my 16.0:1 AFR cruise block by one row to try and get a leaner cruise at highway speeds. The difference appears to be large. Using the calculated instang MPH in the log viewer, at 65mph, an AFR of 16.0:1 = ~24mpg. 15:1 = 17mpg. Its huge. Just hope running it at 16:1 doesn't melt anything.

Oh, and click on my google ads and send me pennies.

Moving along...

Fixes from tonight after work:

• Valve adjustment on #5 exhaust valve, got rid of a tick
• New driver side valve gasket, should eliminate my only oil leak (so far)
• Checked #5 plug (because it was easy to get to), looks good
• Put a spring on one of the bolts to the driver side header to hold the flange tight when cold
• Tightened a finger loose bolt holding the driver side header around #7.

Took a ride. Car starts wonderfully now since a cranking pulsewidth tweak during lunch at work. Dunno about peppy, which it really isn't, but some acceleration enrichment adjustments made it feel peppier, and it makes neat noises when you rev it in neutral. The wideband is no longer showing ridiculously lean conditions at idle, which was really an indication of a super rich condition (opposite day!).

We'll see how it does on the way to work. I just finished some dinner, I'm going to take a shower and look at the datalog from the drive home and see how the gas mileage was.

Well, drove it to work again...

...plus to the Y and back during lunch, and just now got back from AutoZone. No fuel leaks. The annoying exhaust leak at the passenger header is back. I got some exhaust bolt springs at AutoZone, I'll try to get them on tonight and hopefully solve that leak once and for all. Then I can listen for leaks elsewhere and get rid of all the weird O2 readings.

Car's a dog again. It was kind of peppy the other night, but it's not feeling quite as spunky today. Then again, it's 20 degrees warmer than it was the other night, so that may have a lot to do with it. I also may have an ignition miss. Again. Fucking cars...

Snowballs

A interesting tale of cause and effect:

I've been fighting with this Pontiac for a long time. I couldn't seem to catch a break. Stuff just didn't work right.

To catch everybody up, I've had massive fueling problems for awhile. Just way too rich. Gas mileage, which was near 15 mpg right after I put the Megasquirt on, had fallen to 10-12.

I'd found a torn diaphram inside my fuel pressure regulator. The tear was allowing fuel into the intake via the vacuum line on the regulator. Fixed that. Still too rich, even with the FPR backed all the way out.

I dyno'd the car, and got a stellar 109 hp. Not right. I took the car to an exhaust shop and had them look at the catalytic convertor. It was fine, but there was lost of unburned fuel in the exhaust tract.

I finally got a decent fuel pressure gauge, and pressure was pegged at 60psi at idle. Way too much. Then, to top everything off, it started leaking from a fitting at the fuel filter. I parked it. Tests with the new gauge revealed I had a restriction INSIDE the fuel rail.

So, today I pulled the rail off, filled it with carb cleaner, and blasted it out with compressed air. I put it back on. I then pulled the line that runs from the fuel filter to the fuel rail out of the car and re-did the AN fitting on the end. I put it back on. I hit the fuel pump relay with 12v to fire the pump and watched the gauge.

46psi. I'd done it. I took the car out for a test drive and when I got back, my heart sank. It was leaking from the filter still, plus a leak out of the schrader valve on the fuel rail.

I pulled the filter off, and found the problem as soon as I loosened the clamp. I was greeted with a fine spray of fuel from a crack in the filter. I replaced the filter and put it back on. I then pulled the schrader valve from the rail, slimed it with thread sealant, and put it back on.

Fixed. Finally. I hope.

So, to recap:

A small amount of dirt in the rail caused a restriction in the return line that forced pressure from the outlet of the pump to the rail to not drop below 60psi. Over time, that pressure tore the diaphram in the regulator, causing a massive fuel leak into the engine. Once I repaired the regulator, it burst the filter and compromised the seal on the schrader valve, causing leaks onto the ground and onto the top of the intake manifold. It's a miracle the thing hasn't caught fire yet.

A little dirt, months of frustration. Months. And wasted gas. 10mpg with $3.50 gas sucked. Now that it's $4, I'm glad it's fixed, and I hope it stays that way.

Blah

So, I finally got my fuel pressure test kit and hooked it up. With the pump on, pressure in rail shoots to 60psi. Turn off the pump, and it drops to 20psi and holds, which is about where it should be with the regulator turned all the way out like it is.

I unhooked the return line and ran it into a bucket, same result, so the restriction is in the rail. Yippee.

I won an auction for another rail assembly last night. $23.50. Hopefully it isn't all full of crap like this one was.

On the bright side, the Datsun has been running beautifully. No smoke, good fuel mileage, though I can't tell exactly how good since the speedometer doesn't work. derp.

Yee-haw!

Well, I drove the Z to work today. Vast improvement over the truck, though a radio would be nice to have.

No smoke. It's wonderful. I'll pay attention when I start it today to go home, but it looks like the new valve stem seals did the trick. Warm idle needs to be raised, but that's all that's wrong so far. I even got most of the interior panels installed last night.

For reference for anybody out there:

If you're rebuilding your Z-car head and using anything other than bone stock valvetrain parts, save yourself three head rebuilds, and throw out the standard valve stem seals. The seals you want are Fel-Pro part number SS 72686. They're for a Ford Capri V6. They fit the Z guides perfectly, and are much shorter than the stock guides, giving you lots more room for those thicker spring retainers and larger camshaft. They're also designed to be immersed in oil and still not leak, which is a big consideration if you use a high volume pump and end up with a lot of oil up in the valvetrain. Autozone usually has them in stock.