Failed CO emissions - all controls removed - where to start?

[Dave WM]

here is a short video of a stock harness, maybe help you figure out what you have and or are missing

 

[thetwood]

1 hour ago, Dave WM said:

here is a short video of a stock harness, maybe help you figure out what you have and or are missing

 

That's perfect. Traced it out and the temp and thermotime branch is what's in the picture above. Wasn't hooked up to anything. I'll get a bullet connector tool and a plug and make a new harness for the temperature sensor. Going to ignore the thermotime at this point since I don't have a cold start.

Also, you're right. There is no Air Regulator at all. That's all missing.

[superlen]

I just noticed this thread and wanted to give you a thumbs up on persevering. I don't have much to add as others have been giving you great advice.

You're close now. As Zed said once you start feeding the ECU a real coolant temperature sensor resistance instead of an open connection, the fueling will change, but then you can begin to figure out all the other things that have been modified on the engine in the past to compensate.

I will add that the AFM position is rotated but shouldn't make a big difference. There is a weight on the flap that is affected by gravity, but the governing force in the device is the spring. The weight helps as a smoothing function on abrupt air speed changes and the momentum gives a bit of overtravel when you tap the throttle. The overtravel is by design to give a bit of extra fuel and is akin to the "accelerator pump" on a carburetor. Perhaps I should test the flow in two orientations to see if I can detect any change in the AFM output.

I also have some spare harnesses that you are missing that you are welcome to if needed. Realistically, you can make one faster, and the ones I have are old and connections would need to be cleaned anyway. Still the offer is there, just pm me your address if you think they will help.

Len

[Dave WM]

No AAR will make starting a bit of a pita, you will have to prob feed it some throttle to give the extra air it needs, but not a huge deal. The stock FI is designed to operate with no user input, just turn the key to start with no other inputs. Then you can drive it immediately. With so much deleted it will require some more work on the driver to compensate (that is once you get the hooks for the temp sensor worked out). After you get it starting with some degree of reliability and correct mixtures, you can start acquiring the missing parts (like the AAR and a working CSV) to ease the work load on the operator.

[thetwood]

23 hours ago, superlen said:

I just noticed this thread and wanted to give you a thumbs up on persevering. I don't have much to add as others have been giving you great advice.

You're close now. As Zed said once you start feeding the ECU a real coolant temperature sensor resistance instead of an open connection, the fueling will change, but then you can begin to figure out all the other things that have been modified on the engine in the past to compensate.

I will add that the AFM position is rotated but shouldn't make a big difference. There is a weight on the flap that is affected by gravity, but the governing force in the device is the spring. The weight helps as a smoothing function on abrupt air speed changes and the momentum gives a bit of overtravel when you tap the throttle. The overtravel is by design to give a bit of extra fuel and is akin to the "accelerator pump" on a carburetor. Perhaps I should test the flow in two orientations to see if I can detect any change in the AFM output.

I also have some spare harnesses that you are missing that you are welcome to if needed. Realistically, you can make one faster, and the ones I have are old and connections would need to be cleaned anyway. Still the offer is there, just pm me your address if you think they will help.

Len

Thanks @superlen, I appreciate the support.I must admit that I get frustrated at times and if it was easy to just pay someone to fix everything I'd be tempted. But my son and I keep working, with all the great help we've been getting here.

Thanks also for the offer of the harness. I'm planning on just building one up. But do have a question. Do you know what size bullet connectors are used on the 280z? I need to get some and there are a lot of sizes. Not sure which is correct.

[SteveJ]

You can find the right sized bullet connectors at http://vintageconnections.com.

[thetwood]

Thanks @SteveJ

[thetwood]

Progress. Parts arrived and my son helped me with a bit of work. I went ahead and ordered a new temperature sensor and temperature gauge sensor. We installed both, then created a new harness and hooked up the wiring harness to the temperature sensor. I cut off the connectors that were on the temp gauge wires, put a new bullet connector on the yellow wire and hooked that up to the temp gauge sensor. We testing continuity of the temp sensor at the ECU (looks good) and tested the temperature gauge by grounding the yellow wire (looks good).

After hooking everything up, the car started up and seems to be running better than it did before. That makes me happy. Seems to be using the temp sensor now and the temp gauge is working correctly.

My next question: what's next? How do I judge how it's running (other than going back to emissions)? What do I work through next to make sure it's getting better?

And a big thank you to everyone here. This sure can get frustrating, but your support has made a huge difference.

[thetwood]

I've been looking for a charcoal canister and haven't been having much luck. Can I use a 280zx charcoal canister instead of the 280z? It's still 3 nipple, so I'm assuming it would work fine. But didn't want to spend money before making sure.

[EuroDat]

16 hours ago, thetwood said:

I've been looking for a charcoal canister and haven't been having much luck. Can I use a 280zx charcoal canister instead of the 280z? It's still 3 nipple, so I'm assuming it would work fine. But didn't want to spend money before making sure.

It should be ok. The 3 lines are the same on all the variants.

Tube layout.

Yellow: Distributor vacuum.

Green: Purge

Blue: Fuel tank

White: Carbs. This is for the 240Z, 260Z carb models and also fitted to the early 280Z, but then with a cap p/n: 14964-F1700.

The three tube variant part numbers: 14950-N4800 and 14950-P8200 (280ZX)

The four tube variant part numbers: 14950-N3600 and 14950-N4200 (early 280Z)

 

Edited November 10, 2019 by EuroDat

[Dave WM]

The best way to test how the mixture is would be to 1st make sure the ign timing is correct, then using a brand new set of plugs, install and take if for a short test run, normal driving, of about 10 miles, then pull the plugs and read them. they should be very nearly white, just a tiny tan if any.  I set my timing at 10 degrees with a idle of about 800 rpm. I don't know if this will be good enough to let you know about how you will do for emissions, but if they are turning brown after a short run like that I would think its going to fail.

[Captain Obvious]

12 hours ago, EuroDat said:

White: Carbs. This is for the 240Z, 260Z carb models and also fitted to the early 280Z, but then with a cap p/n: 14964-F1700.

I'm not sure what that fourth connection was intended to do. The first year for the carbon canister was 1974, and (even though the 1974 model used carburetors) they capped off that fourth connection.

I don't think "CARB" means "Carburetor".  I would guess that it means "CARBON".

I've never seen a picture or vacuum diagram that did NOT have that fourth connection capped off. I don't know what it does.