cozye

check for continuity between pin 1 of the ECU connector, and the negative side of the coil. If that is good, you should be fine there. Do you have the water temp sensor connected ? Sounds like it's bad, or unplugged. If it is connected, what is the resistance reading between the two pings on the water temp sensor ? The tach bouncing around could be a bad tach, so I wouldn't put a lot of faith in that.

Yeah, let me know how it goes. I've already dissassembled my intake fuel system, new intake gasket and inspected AFM throttle body, new injector gaskets, etc.. and put it back together. Didn't help me. Your M3 story is good info though. As I mentioned before, my first sea foam treatment brought the vacuum up 1.5. It may be just gunk, goo, and carbon build up on the top end causing my issues. I did advance my AFM module spring 5 teeth to get it driveable and it is pretty drivable with that setting although the slight stumble is still there. I think I'm about at the point of just cleaning/lubing the top end a few times with a seafoam or similar, and just getting some miles on it and see how it does.

balance test at 500 rpm didn't reveal anything. would drop equally with each cylinder pulled.

External tach and dash tach agree on 800 rpm. The video was taken on an iphone, I think it has the tendancy to magnify high frequency sounds and not the lower frequency, so it makes it sound faster and makes the injector ticking seem louder than it really is. Yeah, i've looked for the spark in the dark test. PVC valve is new, PVC valve hose is new. Oil dipstick, oil filler cap, etc.. checked. valve cover gasket is new. rear main seal is new. car dies with idle screw turned all the way in. timing light put on all cylinders too and watched reference point on crank for irregular pattern or skipping trigger on light. I've got a brand new ignition system on the car. It's firing flawlessly. I'll try the balance test again with a much lower rpm and see if I notice anything unusual.

The injector noise isn't as loud now that I got them cleaned and flow tested. It was two injectors that were making the noise. Too fast for valve noise as you could pull the oil cap off and watch the cam lobe, which wasn't turning near that fast. You could put a screw driver on the injectors with your ear up to it, it was obvious. I've run through the valve adjustment twice, once when I first got it and again just last night to double check. The tach reading was right, it doesn't have 4/6/8 setting, just different scales. You were probably looking at the scale on the top and not the one on the bottom. It was at 800 rpm. The reason I haven't called it a miss is that it doesn't have a rythem, and is sporadic. I think it's actually just slight lean popping. The more gas you add to the A/F mixture, the more it goes away. When it does it badly, it will "afterfire" back through the intake. I've done the balance test, bunches of plug reads, etc.. All cylinders are firing.

I've tried timing at 10-15 degrees, doesn't make a huge difference where I time, except that the more advanced timing will lessen it slightly, but too much advance causes it to accelerate slightly less at higher rpm. I've got it set on about 11 now, 10 is what the manual calls for. It's running a bit lean, at worse you will get the accasional intake pop. It seems to vary depending on outside temp a little, and how warm the car is. The warmer the car is the more it stumbles, but it's not really a huge difference. It still does it when it's cold too. So when taking off in 1st gear it's the most noticable, mostly I believe because you are at lower rpm and any hesitation or stumble in first is going to be felt a lot more due to the gearing. It will do it in all gears, but the higher the gear and the higher the rpm the less it is felt. I would say about 2500 rpm and up you kind of have to be paying attention to notice it. Also, it's worse at slight or partial throttle openings. the TPS switch has been tested thoroughly, but when you give the car a lot of gas (30-50% throttle or more) it's either unoticeable or non existant. It has a slight stumble at idle, almost like the timing is wrong or it's got a hot cam in it (it doesn't, it's 100% stock), it will do it worse under a load. Here is a video taken a couple weeks ago. I've got the vacuum up a little more than this now but it's doing the same thing. The injectors aren't as loud since I've had them cleaned up, if you get to the part of the video where I'm by the exaust, that's the stumble you hear it just kind of comes across a bit high pitch from the video camera http://www.youtube.com/watch?v=RGj3CQ_SCks

I've got a 25 page thread going on another forum and have been pulling my hair out for about a month on this car. Thought I'd post over hear and maybe get some fresh ideas. History. I bought this car about a month ago. I'm the 3rd owner. Car has 108k miles on it. Solid body, garage kept for it's entire life exept the last two years. Original owner was a female who bought the car out of med school in 78 and garage kept it for the first 95,000. Records in the car show that the original owner had 89000 miles on it in the mind 90's, so it hasn't been driven much at all in the last 15 years. Original owner supposedly only drove it a few times each year and would get the oil changed. 2nd owner didn't do much maintenance to the car and had it for about 13k miles. It was running very rough when I picked it up, exhaust manifold gasket leaking, plugs worn out, bad distributor cap, slipping clutch, etc.. 2nd owner said when they picked up the car it ran pretty good, but had a slight stumble/hesitation at lower rpm's. This is what I've done. Replaced all tune up parts, ngk plugs, cap rotor, wires, etc.. new exhaust/intake manifold gasket. no longer leaks. new clutch/pressure plate, etc.. fuel pressure test - shows 37psi with FPR disconnected. 33psi at idle vacuum at idle is currently 15.5hg carb sprayed all areas of intake, head, vacuum connections, throttle body, etc.. couldn't find any leaks rigged up a smoke machine to intake, smoke tested it 3 or 4 times, couldn't find any leaks rigged up a "boost test" to try and find vacuum leak, around 2 or 3 psi with air compressor connected to brake booster vacuum connection. Couldn't find any leaks compression test when I first got the car showed all cylinders getting between 145-155 psi. Might be a little better now after valve timing and adjustment and oil change (old oil was thin and gas) valve timing check showed still in spec, but went on and put gear at 2nd position which got the timing mark perfect like new. Valves adjusted, but were very close (only a few off by .001) been through the FSM and performed full check on entire EFI system, everything checks out ok. I've done this about 3 times, including air bypass, thermotime, etc.. Pulled AFM off car and performed full resistance test, and voltage output test with 12v applied. Replaced ignition with crane xr700 optical setup. Cleaned and tested vacuu advance mechanism. Vacuum advance dashpot holds vacuum and doesn't leak. EGR valve replaced Water temp sensor tested ok, replaced it anyway since it was cheap. All injectors were pulled off, sent away for cleaning and flow testing. Vacuum on the car was running around 14hg, I did a sea foam treatment and got it to 15.5hg. The car has a stumble, especially noticeable at lower rpm. Runs a bit lean. Can't figure out if it's lean due to wrong A/F mixture, or motor pulling low vacuum for some unknown reason. If I add a bit of fuel buy faking the system (moving AFM gear, or jumping TPS to full enrichment), it smooths out quite a bit. It does it worse when it's warmed up and hot. I've done quite a bit of testing, plugging vacuum lines, etc.. and can't pin it down. I've had quite a bit of suggestions from another forum and have tried a lot of things, maybe some things I've forgotten to list above. Any help would be appreciated.

How'd you source the parts to rebuild the Throttle Body? Is there a kit available ? Sorry for the threadjack.

What is your vacuum gauge reading at 800 rpm idle ? Jumping the temp sensor is leaning it out, actually you should use a 330 ohm resistor to jump the temp sensor, since it's technically never shorted out with 0 resistance. I've been battling a very similar issue on my 78. I'll be watching what you come up with here. I've got quite a lengthy thread going on another forum about it.. http://www.zcar.com/70-83_tech_discussion_forum/is_my_fuel_pressure_regulator_bad_893825.0.html Here is what I've done so far.. complete test of entire FI system per FSM and FI guide, including wiring harness, AFM module, injectors flow tested and serviced.. replaced all vacuum lines that were suspect. Pinched off, plugged, prodded, etc.. any possible source of an external vacuum leak replaced EGR valve replaced intake/exhaust manifold gasket replaced both intake boots complete tune up, wires, plugs, rotor, cap, etc.. Checked timing, verified timing mark with TDC Compression check, all cylinders around 150psi or so. All new FI connectors (there are 10, including 6 injectors) used 3 full cans of carb cleaner giving the whole intake a bath trying to find a leak It acts like a vacuum leak, but I can't find one. The thing is, when you add more fuel it smooths it out, but I could just be masking a vacuum leak. On the other hand, incorrect air/fuel ratio will look like a vacuum leak as well. I fooled my AFM into supplying more gas as a test by adjusting the gear up 12 notches, which helped, but only down low. When I drive it after fooling the AFM the top end was completely down on power. Vacuum on mine is only around 14hg. I can't get it higher than that no matter what I do, other than giving it more fuel. I've seen a few threads around on the net describing similar situations with 77-78 cars, but no one ever seems to fix the issue, or at least post back to the thread stating what the fix was (more likely).

Thanks for the link. I've been wondering about this.

what do you use to recoat the bare metal hardware to get that original yellowish gold look ?

interesting thread. I'll be keeping an eye on this one as I'm doing a "refreshstoration" now myself.

That definitely helps. The downloaded FSM I have does have a section on AC, and it has a schematic of the system including those "magnet valves". At least I have a stating place. Thanks!

Thanks Jeff. That's very helpful. On the passenger side shock tower, there are some vacuum lines going to those devices in front of the fuseable links. I'm not sure what they are or where the vacuum lines are supposed to go, thats one of the hacked areas on my Z. I can't tell from the photo, but the rest of those photo's are awesome and will definitely help with the rest. sblake01, I do have the FSM and have studied that diagram, but it leaves a bit to be desired and doesn't show what I'm looking for. Any other ideas or source for a vacuum diagram on this car? I've got a couple of other service manuals on order, maybe that will show me what I need.

Thanks for the pics. It is very close, however I think you are missing some stuff as well as I notice you don't have air and possibly some of the vacuum stuff I'm looking for on the passenger side. No heat either ?

Hey Guys, I'm looking for a detailed large pic of the engine compartment on a 77-78 280z, preferably restored or at least at OEM spec. Mine has been hacked on a bit with the vacuum lines, wiring, etc.. and I'd just like to know how it's supposed to look to aid in putting it back. Appreciate any help Eric

I'm interested as well if someone could pass along the info.

Hi, My wife and I've recently acquired a 78 280z. I've already got it home in the garage and have started to go through it to get it road worthy. We will restore it as original as we can get it I reckon. Haven't made up my mind yet weather to go all out frame up, or just clean it up as best we can with new paint and interior. It's got 109k miles on it, factory air that still works, perfect dash, very little rust, and the clock even works! It was missing pretty bad when I picked it up, but I've got it running a bit smoother now. I'm fixing an exhaust manifold leak on it now, clutch slips, and needs brakes. I've been lurking a bit for the last week or so but figured I'd introduce myself as I'm sure I could use some help. Eric