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

[thetwood]

8 minutes ago, siteunseen said:

My similar fuel rail has a T out the back. One side to the cold start, the other to an original equipment fuel pressure regulator from a '78. Worked out good for me. I can post up some pictures tomorrow if you want.

Cliff

That would be great if you could. I don't mind continuing to get closer to stock, but it's going to take a lot of searching for parts, tracking things down and cost of course. If I can continue using things we already have that helps...

My first goal is to pass emissions. Doing so allows my son to drive to school and back and buys us time to make additional changes.

[EuroDat]

Good move and reinstating the carbon canister, replacing the gauge and sending the injectors off for testing. You are eliminating some of the unknowns.

Once you get the injectors back or replace them, you can start sorting out you pressure regulator. Test run the pump and adjusg the FPR to 36psi. Then connect the vacuum line.

I don't think I would worry about the CSV or the AAR for now anyway. Mine starts easy in the summer and even in the early spring and late autum I can start it and play with the throttle for 30 seconds and then it idles on its own.

My experience with these old systems. If poeple start playing with the system, which is very clear in your case, they eventually focus their attention on the AFM. The temptation to play with the spring and ease of access is too much. See link for testing the AFM.

http://www.atlanticz.ca/zclub/techtips/afm/calibration/index.html

 

Plenty of other neat tips on Atlanticz. A good read while waiting for the injectors to come back.

http://www.atlanticz.ca/zclub/techtips/EFI&fuel.htm

The other thing I would reccomend is going through all the tests in the EFI bible.

 

Edited September 4, 2019 by EuroDat
Link to EFI bible

[Patcon]

I guess the fuel rail depends on how strict the visual inspection is? In some parts of the country they compare the engine to sample pictures to determine if components have been removed or tampered with. If a visual inspection isn't a big deal, Then the fuel rail can probably remain for now

[Pilgrim]

I doubt thr visual matters. Most just check emissions. For that matter, few people know what the original looks like.

[thetwood]

Haven't made a lot of progress yet. Still planning on pulling the injectors to have them flow tested, but haven't done so yet. It was my son's 16th birthday yesterday and he wants to drive his Z to the local Cars and Coffee this Saturday. We go a lot, but he's never gotten to take his own car. Seems like a worthwhile reason to wait a few extra days...

But I did receive a fuel gauge from Amazon yesterday. Put it in place of the Jegs inline fuel gauge and tested again. Got similar readings as before, and nowhere near 36. With the Begi fuel regulator hooked up, it sat at 10 psi. With not vacuum to it, fuel pressure was 16. 

Will send off the injectors this weekend and hopefully get some answers on that next week. But fuel pressure doesn't seem nearly what it should be.

Edited September 6, 2019 by thetwood

[Zed Head]

The pressure reading is actually great progress.  The numbers are the most important part of working with EFI.

You're at a point where you can calculate a cheapest path to where you want to be.  Find the atlanticz.ca page about calibrating your AFM and see if it has been messed with.  It might be most cost-effective for you to just buy the right injectors and calibrate your AFM.  If you send your injectors out and they're high flow rate you'll need to buy new ones anyway.

It's a learn-o-rama with the old EFI systems.  Have fun.

I found the page.  It's worth a read.

http://www.atlanticz.ca/zclub/techtips/afm/index.html

[thetwood]

Have been reading through the AFM documentation, then went to the car. The AFM is not original. It's from JEGS. I can't find anything on their site with the model number on it (A31-625 000), but it seems to be listed for an L28 and there's some faded marker on the body that looks like it says 280ZX.

The cover was sealed, but popped with a bit of a pry from a screwdriver. Inside, it doesn't look exactly like what's in the documentation but is close enough to work on. Glue blob is intact and I can't see where it's been adjusted. I'll go through it in much more detail, but just doing the quick fingering check, moving more than about a tooth in either direction did bad things to idle. I'll dig into the tests and go through the other suggested checks from the document when I get more time.

[AZDatsun]

It’s actually made by “JECS” and that is oem


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[Captain Obvious]

That AFM has been messed with in the past. Don't know if it's been adjusted, but that cover was definitely removed and reinstalled in the past. The glue's wrong.

That said... Other than trying to verify that it's the correct AFM for the system, don't spend any time worrying about adjusting it right now. That would be one of the last things to mess with. Get the fuel pressure correct and tracking intake manifold vacuum first, Fix the PCV routing so you aren't pulling huge amounts of unmetered air. Get the AFM mounted properly so gravity has the correct effect. Search out and fix any other vacuum leaks in the system.

Do all that first and go from there.

BTW - I recently stripped down an 82 motor and it has the same fuel rail and regulator system as the stock 78. If you just can't seem to get the aftermarket stuff working, we can work out some sort of trade for your aftermarket stuff. I know it's a "downgrade", but it comes with the advantage of being a known entity.

[Zed Head]

If the glue blobs were intact after you removed the cover then leave it where it was with the intact glue blobs.  Never adjust it.

The procedure I linked to is for getting it back to where it is supposed to be.  The AFM should never be adjusted from its factory position.  There are better ways to tune the air-fuel ratio.

Edited September 6, 2019 by Zed Head

[EuroDat]

11 hours ago, thetwood said:

Have been reading through the AFM documentation, then went to the car. The AFM is not original. It's from JEGS. I can't find anything on their site with the model number on it (A31-625 000), but it seems to be listed for an L28 and there's some faded marker on the body that looks like it says 280ZX.

The cover was sealed, but popped with a bit of a pry from a screwdriver. Inside, it doesn't look exactly like what's in the documentation but is close enough to work on. Glue blob is intact and I can't see where it's been adjusted. I'll go through it in much more detail, but just doing the quick fingering check, moving more than about a tooth in either direction did bad things to idle. I'll dig into the tests and go through the other suggested checks from the document when I get more time.

It's a standard looking 280Z pre August 1977 AFM. Definitely not 280ZX. You can tell by the contact switch for the fuel pump. I have one with the same part number.

They produced a lot of part numbers for the hole sries, but essentually you have two types for the non turbo model. With and without switch.

Like I mentioned before. I would check the calibration by following the steps on Atlanticz, but only adjust it if you get a realy wonky reading.

[Zed Head]

I used an online calculator just for fun and it comes up surprisingly close to "turbo" injector for your measured pressure.  Assuming that the 188 cc number is at 36 psi. Some flow rate charts aren't clear on what pressure they measure at.  

Whatever you do, keep track of your starting points so you can reset them if needed.

http://www.atlanticz.ca/zclub/techtips/injectors/index.html

https://www.rcfuelinjection.com/technical