Everything EXCEPT the $&@!!*! Engine Starting
As the spoiler title makes clear, I still haven't gotten the engine to start. Here are the steps I've taken so far:
1) Shane the ECU Guru has been reviewing my TunerStudio settings and and has suggested some changes along the way. He's experienced with Miatas. I'm sure some additional tweaking will be needed when the thing is actually running, but I'd say Shane's involvement rules out any fatally wrong ECU programming problems.
2) Tested the injectors and the spark plugs. They respond appropriately to the ECUs commands.
3) Above: installed a fuel pressure gauge. The pressure reads around 40 psi when cranking, which is in the middle of spec.
4) Suspected I may have gotten the cams out of synch when I installed the timing belt. I did have them one tooth off. Since I did that job a year and a half ago, I read some bad reviews of the timing belt brand that I used so while I was in there I replaced with a Gates.
The marks used to synch the cam timing are awkward to read. The alignment depends on the angle you're looking at them from and it's easy to get them wrong. My brother Uncle Ray the Engineer Who Can Actually Work on Things in Real Life came over to double check my work before I put everything back together. He's done 3 Miata timing belts in the past, and he's a very good mechanic, so I feel pretty confident this is now correct.
5) Changed out injectors as noted in the previous blog post.
6) Decided that the spark looked weak and so replaced the coil pack. This was kind of a desperation move. I've never heard of a Miata coil pack going bad.
7) I've checked the base ignition timing LOTS of times - repeated after every other change I've made. I don't think this is the problem.
My next area of exploration is that my starter motor is cranking the engine a little more slowly than optimal. It also drains the battery more quickly than I would expect. The battery tests good under load after recharging so that's not the problem. Next I plan to test for voltage loss between the battery and the starter. If that's not the problem, I will probably replace the starter. In my past experience, starter motors are either good or they fail completely. So "cranks too slowly and uses up too much power" would be surprising. However this is the OEM starter motor, 22 years old, so it's possible.
Everything EXCEPT
The startup manual for my ECU says that when things don't go right, step away, cool off, and come back. I think this is generally good advice. My frustration and disappointment are reaching levels that sometimes require two or three days away before I can gird up my gumption to try again.
When I'm avoiding the engine start headaches, I've been gearing up for bodywork and painting. I have a paint sample and plan to paint one of the doors to test out the color as well as my own set up and techniques. In anticipation of this I have upgraded some of my kit.
My compressor is 88 gallons so plenty of capacity, but the pump is only 11 cfm. The paint gun I've been using is a 3M Accuspray, which wants more like 12-13 cfm. This is fine for primer but would be undesirable when trying to keep up with a base coat or clear coat job. I looked into replacing the pump but that would also mean replacing the motor and rewiring the power supply - which gets a little spendy. So on the recommendation of Aussie YouTube car painting guru The Gunman I got an ANi 150 from Spray Guns Direct in the UK. It's LVLP, and his favorite gun when compressor throughput is a consideration. Even accounting for shipping cost, Spray Guns Direct beats US prices for similar grade equipment.
I also installed an intercooler on my compressor (above). This is the best way to get moisture out of the system - cool the air rapidly as it comes out of the pump then straight in to a water/oil trap. It was a little bit of wrestling around with tube flaring and tube bending, but it really works well. The tube going in to the heat exchanger is too hot to touch and the one coming out is not even perceptibly warm. Water and oil in the air line is a sure-fire way to ruin a paint job. Also, I'm kind of lazy about emptying the water from the bottom of my compressor tank and every time I do, I think "I waited way too long to do this." This trap is right out where I can see it.
The most expensive part of this project was all the fittings/adapters. I think the whole thing was about $75 (however my brother Uncle Ray had the copper tube laying around, so maybe more like $100 if I'd had to buy that).
For a long time I've had a painting station with a regulator and an oil/water trap, but I decided to improve this by adding a dessicant trap. This is a regular home water filter housing rated for 100 psi (notice there is a regulator in front of it, so it won't be exposed to the full line pressure which is up to 150 psi).
Instead of a water filter, you put a piece of PVC pipe down the middle. The PVC has small holes drilled around the bottom, enough to add up to the diameter of a 3/8 inch air line (all the fittings and parts for the paint gun are 1/4" so this should be more than adequate). You do have to reverse the flow direction so that the compressed air comes in from the top, down to the bottom of the PVC tube, and then is released into the dessicant, then goes up and out to the spray gun. This is not my idea - this same setup is widely recommended by home/garage painters all over YouTube.
I will have a filter on my gun to prevent any of these little do-dads from clogging up the works.
The product above is just slightly more volume than is needed. Turns pink when it needs to be re-dessicated so that's handy.
Taylor and Materials Science
My 13 year old daughter Taylor announced that she wanted to do TIG welding for her science fair project. I promise I did not put her up to this. We talked about what to investigate and how, and landed on testing the tensile strength of TIG welds that are untreated, annealed, and heat treated. I knew this was rather ambitious for a 13 year old science fair project but I felt compelled to support her.
Here she is welding her material samples (above). 16 ga mild steel. 16 of them.
Hardening: heat to red glow with oxy-acetyline torch and dunk in oil bath.
Annealing: heat the same as for hardening, but cool down in sand to slow the cooling time. This actually made the can uncomfortably hot to touch.
The verdict: tensile strength was greatest for the untreated welds. Annealing and hardening both weakened them.
I am pleased with this result because otherwise I'd have had to invent excuses for not annealing or hardening all of my welds.
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