cygnusx1

Not sure why the thermostat gets gutted? Might be off topic. The only reason I can think of, is to prevent it from failing in the closed position? I make lots of power in my stock motor with a stock thermostat and have no cooling issues; even on a road course. I am not good with SU's so I can't help there. I would suggest electrical issues in the coil charge circuit. Is the coil getting a strong 12volt charge, at speed? Plug wires, plugs... Good luck. Just thought of this after looking at the photos...is the throttle linkage opening the throttles all the way?

Don't overlook your air intake system either. I have no idea what you are running, so I say this blindly. Also MUST confirm cam timing.

I hope you weren't directing traffic. ;-) Speaker wires for sure.

Screw an analog gauge into the block temporarily and get a REAL reading. You might want to blow some air into the port on the block just in case it got plugged by sludge. I would also do a filter change for the heck of it.

If your plugs all look like that marshmellow, then you are losing mileage due to another reason. Dragging brakes, low tires, driveline drag, or a fuel leak. The little screw in the corner of the AFM is a BYPASS to allow air to go around the flap without getting metered. The more air you let sneak through that screw (counterclockwise), the leaner it idles. Just an FYI: If someone opened up the idle mixture screw in the AFM, all the way, it might idle lean. To compensate for that, someone may have erroneously turned the AFM tooth wheel to the rich side, making it idle perfectly. However, that would make it too rich everywhere else but idle. OTOH, toasty brown plugs would indicate that the combustion mixture was OK..so I refer you back to my first lines above. If I remember correctly, each tooth in the AFM represents about a 3% change in fuel mixture. PS. What kind of driving are you doing? A perfect Z can get 12mpg if driven hard. If it gets that on the highway at 55mph, then you have an issue.

Head gasket leak pushing oil out the main seal is a long shot at best. By the time the oil gets to the rear main seal, it has already dropped down to crankcase pressure, which is much, much, lower than oil pressure. Make sure all your crankcase breather systems are, well, breathing. Changing a head gasket in a Z is relatively easy. It's one of those jobs that seem like a big deal, until you have done it. Looking back at it, you will say, "That was easy". Don't pull the head though until you have totally proven that the head gasket has failed. So far you don't have proof. Sometimes you just have to drive it until it gets worse. My car had three shattered pistons and a severely breached coolant passage in the head gasket with gallons of water out the tail pipe...and it still started and ran!

Or...block off the vacuum hose and drive it without power assisted brakes temporarily, if you need to for emergency purposes. It can be done safely. Just be very vigilant and aware of the increased braking efforts.

My LC1 wideband with MSII automatically keeps the AFR's in check. ;-) Yes, the cool air feels like NOS!

...and working under an S30 dashboard is the only Yoga I do.

It takes some persuasion to get them on. Don't put rubber back on the steering rack! Everywhere else it's OK but the rack on the Z cars needs to be pinned down with a stiffer material than rubber.

Cool color. Does it have pearl in it?

Must be that German silver.

Replace the little check valve that is threaded into the outlet of the factory fuel pump. Get the boost/vacuum gauge linked above. Most of the VDO ones will require the VDO turbing kit. The tube is a bout as thin as spaghetti and is easy to route to the dash. Then you can velcro the tiny gauge on the dash where it meets the A-pillar. Cake install. The gauge you found at Walmurt is for your toolbox, not your engine bay. I like the SunPro gauges....cheap and little. (caution this has been back ordered for months now, and they keep pushing the dates out) http://www.summitracing.com/parts/SUN-CP8213/

BMW Arctic Silver was my choice....almost the color of sand blasted aluminum.

I only learn that it hurts, after I have hit myself with the hammer. I speak from personal mistakes. ;-) BTW, Putnam is a county in NY. I also perform grammar mistakes.

Looks like some fairly critical rust in that photo. I would be taking welding classes right about now. I think you will need to do custom cut and fab work there. I know floor frame rails are available but I dont think anyone makes the forward sections pre-fab. That's right where the suspension and engine loads tie in. Not an area that you want failing.

I am not entirely sure what symptoms it may cause, but I would think decreased clutch capacity would be one symptom. Inconsistency, might be another side effect. BTW It's not the flywheel bolts, it's the bolts that hold the clutch to the flywheel, that are the issue in the cases I have seen.

The Fidanza flywheel is infamous for people tightening the bolts that hold the clutch...BUT the bolts actually bottom out in the tap hole and don't fully clamp the clutch in place. It's very deceiving. You need to use shorter-than-stock screws or grind them shorter. Washers work too, but I prefer using shorter screws, no washers, and locktite. Fidanza also did not tap the blind holes all the way down, consistently, which exacerbates the problem. Get a metric bottom-tap and finish their job for them, so that all the bolts can fully seat. This may or may not be your issue but it was worth mentioning here.

There is a procedure in the FSM for testing the fuel pressure regulator. You can get the 77 manual online. If the regulator passes the tests BUT you are getting low fuel pressure at high RPM/Loads, then I would look at your fuel supply line. i.e. Fuel pickup tube in the tank, fuel pump inlet, fuel filter, fuel lines, and last but not least the fuel evap control system, which could cause pressure/vacuum to build up in your fuel tank. Besides all that, check all the basics first, then move on to the EFI checklist stuff in the FSM. Often, one can focus on one component only, and miss the actual problem.

I would try to get a factory spec. regulator to be sure the fuel mixture curve does not change too much from the original intention. Rockauto.com has them. The turbo regulators usually have a 1:1 ratio against boost. I am not sure what their vacuum curve looks like. Most adj. regulators can adjust the base pressure which alters the entire fuel curve linearly. If you are running boost and want to tweak the actual fuel curve, look at a Begi Regulator with adjustable gain and onset.

I doubt it's my car. I'm as far away from you in NY as possible. I am all the way on the Southeast side.

My 240, with three Webers, on a stock L28, with 6-1 headers, 2.5" exhaust, and a 12lb flywheel.

How else are electrons supposed to travel 5 feet?

Heat is the real enemy though.

Common we can get this thread to 100 posts! I think that since the damper was so close to the fuel pump, Nissan enginerds have it in there to dampen the pulsation from the pump. They didn't make obvious provisions for the injectors pulsing the rail pressure.