NewZed

The thermotime switch is supposed to heat up through an internal resistance heater and break the CSV circuit after so much time on Start, or after the engine has heated up. Time or thermo. Not saying that they always work, just that that's why it's there and what it's supposed to do.

Almost had it. I looked for that but was on the wrong page. Here's a drawing. They might even have the u-joint although they don't call it out separately. Might not be meant for taking apart. http://www.courtesyparts.com/300zx-parts-z32-1990-1996/genuine-nissan-parts/power-train/328-transmission-shiftcontrol/-c-882_883_953_970.html

It does look like a u-joint, but why would there be a u-joint on a "tranny bracket"? How about the u-joint for the steering column instead - http://www.courtesyparts.com/300zx-parts-z32-1990-1996/genuine-nissan-parts/steering/488-steering-column/-c-882_883_991_995.html

I guess you missed my point about the difference between actually "running rich" (too much gas, not enough O2) and high AFR numbers? The gauge is just showing you what's coming out of the exhaust system. What went is in inferred from the number. It's an assumption. No guarantee that it means what you think it does. Your mileage is a good indicator, but you didn't mention it before. Good luck.

You haven't said if you're taking your resistance readings at the ECCS connector or right at the various components like the idle switch, AFM, CHTS, etc. It doesn't matter that the component measures right if the ECCS can't see it, or gets the wrong information. You could help your dilemma by measuring those three things, and others like air temperature, at the ECCS connector and reporting what you get. Start at page EF-16 of the 81 turbo supplement. And, to be sure, do you know that it's "pig rich" or does it just feel like it's rich. [Edited out - waste of words] Maybe the AFRs are a symptom not a cause.

It's easy to pull from below but make sure you first get the car high enough to slide it out once it's on the ground. It's a pain to raise the car when the back of the engine is sitting on blocks. This book is a good read if you wanted some other views on things to look for. Has about a page on grinding and another on jumping out of gear. http://www.amazon.com/Rebuild-Modify-Transmission-Motorbooks-Workshop/dp/0760320470/ref=sr_1_1?ie=UTF8&qid=1359313881&sr=8-1&keywords=bowen+transmission

The early 280Z's PCV system allowed dirty blowby gases to deposit crud around the throttle blade. Nissan moved the hose in 77. I had a similar problem as yours on my 76, with the RPM hanging high after everything got warm. I fixed it with carb cleaner and Scotch-brite. Remove the hose from the AFM to the throttle body and see what's in there.

It could also have an R200. There appear to be 23 variants of body style, transmission and diff combinations for the 79, according to the General Information chapter. Nissan kind of went crazy. Some of them are 2 seaters with 3.7 R200's.

The 1971 S30 Supplement... file here has pictures. They might make sense to you since you have the car. http://www.xenons30.com/reference.html

Looks like someone bypassed the metal hose junction that used to be there for that hose. You can either get the piece and get things back to stock or stick your head up under the dash and just disconnect the hose and replace it. Here's a link showing what used to be there, depending on what year car you're working on (you didn't say) - http://www.datsunstore.com/heater-coolant-junction-tubes-7478-under-dash-p-1687.html a few more things to look at - http://www.datsunstore.com/7578-heating-dash-venting-c-203_206_362.html

A though - are you testing your TPS at the TPS or at the ECCS connectors? Better to test at the ECCS connectors so you know what the ECCS sees. As far as 0.3 volts, I think that the narrow band sensors jump rapidly from .2 V to .8 V when they go rich (low O2). But Ithink that when the mixture is way off, the sensors can foul and don't work right anymore. The wide bands apparently go the other way, in a more linear fashion, from high V to low V when the mixture gets rich. You're not using the same type of sensor for your AFR gauge and the ECCS are you? They're different. And there's a newer type of sensor that uses resistance, not voltage to calculate the ratio. You're probably right on the EGR effect, since there is no extra fuel added with the added EGR gas. I got my gases mixed up. I still can't see any reason for the AAC or the AAR to affect the fuel-air ratio. Good luck. At least you have a good reason to dig in to all of technology behind the system.

It might be a correlation, not a cause. The attached diagram shows that the AAC only bypasses the throttle blade. The EGR gas might affect the O2 reading, since it as adding O2 depleted air to the intake system, which is not the same "reference" air that the O2 sensor is calibrated to. The AAC and EGR system are tied to the same VCM. Looks complicated and the variables probably interact. Regardless, the 81 Turbo Supplement is a good document to study.

The AAR has no effect on the air-fuel ratio. It only lets air past the throttle blade, not the AFM. All air should pass through the AFM, if the AAR is plumbed correctly. 70 ohms is correct for the AAR, that's the resistance of the heater wire on the bimetallic strip. And the AAR only opens when the bimetallic strip cools off. Even so, it's only effect is on idle RPM, not AFR's. The AAC also only affects air flow, not air-fuel ratio, but through a different control mechanism. EGR will affect the amount of fuel, but it only dilutes both air (O2) and fuel equally. There's a great chart on page EF-49 of the 81 Turbo Supplement. EF-35 has a nice diagram of the inputs to the ECCS. 81 was the early days of the ECCS Analyzer though, so much of the FSM assumes it's being used. Makes it a pain to figure things out., but there's still some good clues in there. For example, at mid-throttle, mid-RPM on a warmed-up engine the ECCS should go to closed-loop control, using the O2 sensor. Maybe your O2 circuit is showing a constant lean condition and the ECCS is compensating. Might also explain the jerky behavior, and good perfromance under load. cg knows more about the closed-loop control since he's installed a few complete systems. Just a possibility.

That's a good thing.

I feel like a parrot sometimes for saying it, but have you checked the FSM's? There are complete drawings and diagrams in the AC chapter. Look down in the lower right corner of the drawings for the drawing number and you might find that they used the exact same drawing. That would be a good indicator of sameness.

I would list the parts used to run the engine, to start. Is it a completely stock straight-across swap from a ZX turbo? What year? Any changes from stock? Turbo AFM, turbo ECCS, etc. Have you used the FSM to do some troubleshooting? Need more facts...

I get it. The "boss" being on the drive shaft side, to fit the hole in the flange. Thanks.

Center boss? Can you elucidate? Will the difference affect a transplant from one assembly to another? Just trying to learn more stuff. Would probably help RZ out also.

I thought that there were only two flanges - the ones used on the 76-83 Z and ZX R200's and the one used on the 1975 280Z and the 84 and up ZX R200's. 1975 is the oddball, but otherwise the break is at 83-84. That's bolt-pattern and size I'm referring to. Somewhere in the 76-83 range they changed from square to round in shape but the bolt pattern is the same. You didn't give the pattern dimensions, which are the most important piece.

Weird that you know the resistance range that the AFM pins should show but you don't set your fuel pressure to the stock setting. Are you working from the FSM or just from threads on the internet? 4 psi, plus the +, might not be huge but it's certainly not helping your rich condition.

How much tread is left on the tires?

It's a metric-sized engine. Should have tipped you off when you saw 7/16", that something wasn't right. I found the 202-5406 instructions using Google and "280Z head stud" search words. 10 mm studs typically use a 12 mm bolt head or nut (sometimes 13 mm). You got the wrong instructions. Or the wrong studs and you cross-threaded 7/16" studs in to 10 mm holes. Seems that your main problem in your engine work is picking the wrong people and trusting that they know what they're doing. "Trust but verify" is a good old Reaganism to keep in mind.

I think those might be 12 mm nuts, not 1/2 inch. Just looking at the internet info. Try a 12 and start over. http://arpinstructions.com/instructions/202-5406.pdf Even if they are 1/2 inch, you might still be able to hammer a 12 mm on to get it out. 1/2 inch = 12.7 mm.

Check the specs in the FSM. The lash gets looser when the engine gets warm. If it's quiet in the morning, when cold, you'll have a pretty good idea.

Sounds lean. I would measure fuel pressure before getting too carried away. If it's right, look harder for vacuum leaks, including the EGR system. Download the FSM and read Engine Fuel... chapter to get a good understanding of the EFI system. Might not solve your problem, but it will help you in the long run. In future posts, tell what year car you have, how long you've had it and whether or not it's stock.