Zed Head

So, throttles mostly open, engine working hard to push the car. Did it miss at or stutter at all while at speed? Does the engine use any oil? Could just be an occasional oil ring letting some oil slip by. Or worn valve seals, same thing. Or a leak on to a hot manifold, vaporizing. Do you ever smell burning oil? It has a distinctive odor. It's an interesting puzzle, but if everything else is perfect are you going to tear the engine down to fix it? Might be one of those things you live with when you have an old engine.

Could really use a lot more detail. Where was your buddy? In the car or behind you? Where were the puffs? In the car or behind you? How much time did you spend between 90 and 100 mph? Seconds or minutes? What was going on with the engine, were you goosing the throttle or just cruising along at 95 mph? Literally, it's not even clear that it was your car that was puffing smoke. Maybe someone had a camp fire going and your buddy was looking out the window - "Hey look, I see some puffs of smoke". Kind of kidding, but seriously, there aren't many clues here.

I had a 1978 B210 coupe with 5 speed. Carbureted 4 cylinder. Awesome little car, 38 mpg at a 70 mph, plenty of power, no problems at all over the 4 years I owned it. Sold it to move cross-country, but should have drove it there and kept it instead.

Sorry, odds are you guys are right. I'm certain it was tiny though. I have one of those little jeweler's screwdriver sets, Phillips and slot, and it was one of those small drivers for sure.

I think that the aluminum fuel rail is the key. Lots of fuel volume to boil and condense, to bring the heat up to the rail to be dispersed. I'd been thinking about posting in my other thread recently. I got a tank of gas a little while ago that caused bad heat soak. Ran through it and refilled, and it diminished, now it's almost gone. The winter fuel has to be a big factor.

Forgot to say, I think that I used a small mirror to get a look at the orientation of the slot so I'd have a head start once I stuck my hand in there.

Almost positive it's a tiny slotted head screw. Jeweler's screwdriver size. Slotted heads are the hardest to find, blind, Don't take it all the way out, just loosen it and turn it out enough to release the cable, plus a little more so you can get it back in. There's a tiny hole for the tiny end of the screw to sit in. You'll know you got it it in if you turn the screw in finger-tight and it locks the cable end in. Then tighten the screw down. I dinked around with that several times because I never got the screw tip in the hole before I tightened it down.

If the gear in the transmission had a problem, then it seems like it should have been the same problem after changing the cable. Can you be more clear on what's happening? Is the needle indicating 0, then 40 mph? Or is it bouncing a little bit as you accelerate from 0 to 40 mph? And before, was everything fine until you reached 60 mph, then it started bouncing? Or was it bouncing on the way up to an actual speed of 60 mph, then it stops bouncing? Did you replace the compete cable or just the inside portion? And does the sheath, or housing, for the cable have a kink in it? Not real clear what exactly is going on.

If they do a load test,which I think they do in CA, you'll end up screwed up. The system is designed so that idle fuel is a whole separate function from driving (loaded) fuel. That's why there's an idle switch in the TPS and an idle air bypass screw on the AFM. You'll probably pass idle, but fail 2500 RPM.

Could be that one of the ends is not seated correctly, probably the transmission end. I've found that there's enough play in the sheath to get the fitting partially tightened and have that happen. Take the transmission fitting off, pull the cable out partway, and insert it into the transmission. Then slowly tighten the fitting while rotating the propeller shaft. That way you'll know the trans. end is in, and the odds are good that the speedo end will slip in like it should.

One easy small step up in usable power is the exhaust system, apparently. Shouldn't affect emissions negatively. If you have a catalytic converter, there might be better flowing newer options out there than the stock unit. Slightly bigger pipes, new cat, better muffler.

This isn't about ignition switches or anything causing bodily harm, just a view on how business people think. I had to read it twice to be sure I understood. The words, not the logic. This product's value is not drawing the consumer in. We need to make it worse. http://finance.yahoo.com/news/gm-cut-chevy-gmc-powertrain-warranty-60-000-143947688--finance.html

Did you hear about the constipated mathematician? He had to work it out with a pencil. Har har, a joke from before calculators. You probably could have worked that pencil out with some math though...

Looks great! So, of course, it's time to change things for more power! Seriously, it all looks good to me.

I didn't actually see anything on my AFM contacts and it was a new one from MSA also. Out of nowhere it just quit. I got home, took the AFM out, checked the pins for continuity (none), took off the side cover and fiddled around with the contact surfaces, and it started working. I figured that a hair or something small and hard to see got stuck between the contact surfaces. But I didn't have all of the issues you had before I got the "ten seconds of running after Start", so I went directly to looking at the AFM contact switch. Good luck. The worry will fade away eventually. With these cars there's always something else anyway. I have my favorite tow shop's number in my cellphone.

There's a good picture of the fuel pump switch here - http://atlanticz.ca/zclub/techtips/afm/index.html I wouldn't do any adjusting though.

It's the directionality of the relay diagram that gets me. There's some backward loops in there. Anyway, back to crazy - the start-run for 10 seconds-then die is also a sign of a dirty AFM fuel pump contact switch. I had that happen to me but once it got dirty, it never fixed itself. I had to run power from the rear window defogger to get home. You can see the switch under the black cover of the AFM. Maybe yours was slowly losing contact and now it's totally open. The Start signal runs the pump, the engine starts,and only runs until fuel pressure drops. You can clean the contact with a match book striker. You'll see a tiny spark with the key On when it opens and closes if it's working. It's also another way to test the pump circuit. Take the cover off and rotate the weight and you'll see the lever that opens and closes the switch.

How do you know it was at TDC? The piston barely moves up or down over a pretty wide range of crankshaft rotation. Just saying, that's why they use "dead center" to describe it. It's a very specific location.

Thanks for the explanation. Believe it or not I've wondered about the Start power. No more. I might have enough in my head now to work through that maze of connections. Hard to do though, without a problem to solve.

I was thinking more of dirty connections, not a melted link. I mentioned early on in this thread about someone with a fuse, hidden in the trunk, that would open the connection when it got hot, then close and mysteriously fix itself when it cooled. It's apparently a BMW problem that has happened to more than one person, but is not common. The fuse is in a moist spot and after 25+ years the corrosion builds up. He might fix the problem with just a wiggle of those connections.

This is my new "most likely cause".

I'm still back on "engine dies tach goes to zero". You're right though, I did not delve in to the details, I'm just posting things that might help. Plus, I can't really figure out how exactly that combined relay works. Is there not a diode between Pins 36 and 39? It connects the two relays somehow, but what does it do? No offense to crazy but the wiring diagram and the information you posted are in the same chapter as the tests he's run. The trees and forest thing. Maybe the fusible link you mentioned is the one overheating. Check 'em all.

Your chain guides actually look in really good shape. The used ones I've seen all have grooves worn in them from the links rubbing. The damper pulley looks like a problem. I don't know if Nissan put zero at the same spot on both styles or started from scratch with each design. I think that you could get a 240Z pointer and be right, assuming the damper is in good shape. But it's always good to confirm the TDC mark is correct.

I think I had my befores and afters backward in my other comment. Looks like you're at after-after now so should accomplish your objective well.

#4 and upper right should help.