lol… Went out to crank out all these tests and the car wouldn’t start at all. The positive wire on the reference sensor that I guess I didn’t re-wire well enough popped out of its pin, so I gotta deal with that now again! Weirdly, after wiggling the wire, I was able to get it to crank WITH the DME temp sensor plugged in, but it was idling super rough. Having an impossible time getting the pins out, no matter what I try. So, I’ll either have to pick up one of those de-pinning tools or just buy a whole new connector. I’m convinced this project is going to outlast the heat death of the universe!

 

Caleb,
If the pins are located in the DME plug, then it is important to use the proper crimper to secure the wire to the connector. I cannot not remember where I purchased the crimper and connectors, but source of receptacles is
https://www.te.com/usa-en/plp/junior-power-timer/X257y.html

Google junior power timer receptacle crimper

 

Weird development! I went out to start running tests with the ol’ multimeter and noticed something a bit different.

First off, I tried cranking the car (with the DME temp relay plugged in), and after a few attempts, heard a loud POP that shot the J-Boot off the AFM (I had taken the air filter box out to check the vacuum lines and probably didn’t tighten it back on quite enough when I put it back in).

So, got a single backfire on the intake side. From what I can find, that seems to be a lean condition, which could be caused by it not getting enough fuel, or… enough good fuel?

I was staring at the engine and realized there was a orange-brown residue on the intake manifold, coming from where my fuel line connects to the fuel rail. I tightened that up and fixed the leak, but it got me thinking… Why was this gas residue this strange orange-ish brown color? I’ve never seen that happen. I took off the end of the fuel rail and pumped some gas out and found that the fuel itself was this same orange-brown color. Really can’t make up my mind on the smell test here, but I’m feeling like it is bad…

After I rebuilt the engine, I drained all of the bad gas and replaced it with fresh gas and that’s what I was running on before the valves got bent. Granted, that’s been about 4/5 months now since I did that. Possibly 6… Which I guess is getting close to when the gas could go bad, but still seems like surely that’s not what’s causing this no-start? Could it be that the gas is just not combusting? Is it possible a lot of bad gas got left over from me not draining it properly? I drained it from below the car on the gas tank, but I guess some could’ve been in the lines still? I’m gonna drain the tank again and see what happens if I put fresh gas back in, I reckon! Will report back later!

 

I've seen that before when there is varnish in the tank from old dried up fuel. New fuel immediately turns dark like that. In that case there are usually cornflakes of varnish in the tank that periodically clog up the tank sock too.
You can dissolve and clean it with E85 but it might dissolve any old fuel lines also, particularly the ones back by the fuel pump.

 

BIZARRE TURN OF EVENTS AND FINALLY SOMETHING GOOD (with slightly more bad):

I cracked the code.

I flushed the dark brown gas out of the car. Refilled it with good gas. Still wouldn’t start. Was still getting some mini backfires through the intake. I figured I should check the timing in case I screwed that up somehow. Timing was perfect, still. Suddenly, a little voice told me to take a look at the rotor. Idk why I did it, I just thought I should thoroughly inspect that section again… distributor cap looked fine. I just grabbed the rotor and gave it a tug. It popped off the camshaft like it was NOTHING. My eyes lit up. The screw that holds the piece that the rotor itself slides onto to attach to the cam was MISSING. I ran to my toolbox and there it was, just staring me in the face, mocking me for my idiocy. I threw that bad boy on there as fast as I could and ran to crank it up. Started instantly. I was elated. Of course it was that simple… STILL, it was stalling whenever I’d move the throttle. Need to figure that out, but a consistent start is what I’ve been hunting and I’ve finally got tha!

Now… (This is where the bad stuff starts lol) I gave it another start and suddenly heard a MASSIVE leak under the car. I jumped under there and oil was dumping out so fast lol At first, I thought the bottom end gasket somehow failed just to spite me. Then, I jumped up and looked at the cam tower, because I had been having trouble getting the bottom row of bolts to stay at 15 ft lbs. I immediately tried to tighten it, then my TORQUE WRENCH BROKE. The teeth inside it just slipped or broke or something! Great timing! The oil stopped leaking, luckily, and I just had to stand there and laugh. Nothing totally catastrophic. I need to drain the oil out of it and I definitely need to pull the cam tower off and see what the deal is. Gotta fix the torque wrench or go grab a new one.

That’ll be this week/next weekend hopefully.

But the car will start and idle (as long as I don’t try to move)!

 

Caleb, you live near Hollywood, right? You need to shop this story around with the creative crowd

You didn't state so postitively but do you clearly see that the oil is coming from the cam tower?

 

LOL you should hear the story about what happened when I bought a ‘73 Honda CB500. Wasn’t running, so I fixed it up, had a mechanic look it over, he said it was in great shape. Naturally, I decided to immediately ride to Colorado (my friend was riding from LA to Atlanta, so I was tagging along)! Bike broke down on the side of the road, friend ditched me because he was on a tight schedule. Got stranded in this microscopic Utah town inside a massive national park with 40 people (including the only motorcycle mechanic in all of southern Utah, who was only known as “The Desert Doctor”) for a week where, after Doc worked on it for days, the bike spontaneously combusted. Ended up having to hitchhike 8 hours (4 hours of walking until I got picked up) to the nearest town with a single Uhaul truck so I could get my bike back to LA. THAT’S a movie hahaha!

Anyway… yeah, I could see it dripping down onto the exhaust headers. Gonna have to take the cam tower off to be 100% sure, but I’m thinking that’s the source.

 

Great story about the bike!

OK, so I know my article about oiling is extremely long winded but there are some things near the end of the article about checking the air/oil cooler with a straight edge to determine which gaskets and spacers you need. If you simply didn't tighten the bolts then shame on you but a simple fix. But make sure that your cooler is capable of seating squarely on the block. You wouldn't want to crack it if the internal spacers are holding it proud.

 

Fixed the leak. Can’t seem to figure out what caused it, the gasket had a tear in it, but not really big enough to explain the amount of oil that dumped out. Anyway, it’s fixed now! Got the timing perfect (it’s become a strangely fun job to do on the car lol), the car started right up and idled just fine UNTIL I moved the throttle, of course. Though this time, a weird sequence of events regarding the DME temp sensor. I plugged it in, the car would start and then immediately stall. I unplugged the sensor again, the car would idle for probably 1-2 minutes before it would sputter out. Then it wouldn’t start at all… So, I plugged the sensor back in and the 944 came back to life, but his time, it would idle for as long as I’d let it. The second I’d touch the throttle, it would… ummm… flutter out. I stopped touching it immediately! I did not want anything to change lol

So, here I am. Seems so much like a vacuum leak, but I can’t seem to track it down. I’ve traced all of the lines, they all seem to go to the right place. No visible spots where it would be leaking from. Smoke test isn’t giving me anything. Read it could be TPS, so should probably test that too. Any other ideas?

 

Once you get the hang of the original Arnworx tool, it's fun to use. Especially on the balance shaft belt, it gives you a good reference to how loose it really is.
I'll ask one more time. Fuel pressures?
Now that the engine will idle, you can do this:
Q: What Can I Spray to Check for Vacuum Leaks? A: Any sort of flammable liquid can be used. Carb cleaner, brake cleaner, starting fluid, and propane are all commonly used for the process as they will increase the engine speed when they enter through vacuum leaks.

 

If you set the engine to TDC and pressurize the intake, that can also reveal sounds of hissing air (vacuum leak).

For instance, finding a PVC fitting or cap over the throttle body that you can plug an air compressor into and run between 10-20psi through it (throttle open). The engine needs to be at TDC so all the valves are closed and air can only flow out of the intake. Soapy water can also enhance this by the creation of bubbles.

If a vacuum leak is the culprit, more than likely it will be a large vacuum leak. Again, no more than 10-20 psi

 

I read Caleb's and Harvey's most recent posts.
1. Symptom of engine stall immediately after throttle valve is started to be open is more symptomatic of insufficient fuel than unmetered intake air leakage.
2. As Harvey raised the question, what is the fuel pressure doing at idle and then when the throttle valve is started to be open?
3. I also say "where is the beef" aka fuel pressure data.?
​​​​​​

 

@walfreyydo With all due respect, how do you set all 4 pistons at TDC at the same time?
Seriously, for this test, where you want to get pressure on the intake, you would need to seal off the exhaust pipe and the intake at/near the air filter.
And be very careful, as you can blow out a crankshaft seal doing this. I would start with 5 psi.

 

I was thinking that two pistons are on compression stroke and two pistons are on exhaust stroke. All four should be at the top of travel, but now that I think of it two would be at the bottom of their travel and two would be at the top.

You can disregard my comment about needing to be at TDC then

 

You are correct that two pistons are at TDC at the same time. It's just that one is firing and the other is exhausting.