Rebuilt engine idle problems, running rich

[siteunseen]

Mine adjusted out and works fine. This is just spit balling, a lot of folks remove the BCDD, but have you cleaned the throttle body "throat"? They get gummed up and stick. You can clean that with a toothbrush and lacquer thinner. Just a thought.

There's a lot f info on deleting the BCDD. Blue's Tech Tips cover that I think. You make a cover plate for the hole and disconnect the other stuff.

Edited August 8, 2017 by siteunseen

[rcb280z]

There is a section in the FSM that explains how to adjust the BCDD. Once you understand it, and its function, its fairly easy to adjust. It allows more air into the intake to help burn off the un-burnt fuel while coming to a stop, IIRC. But the FSM explains it in detail.  That devise will help with passing emissions testing which you will have to do because you own a 78 and live in CA. Anything from 76 on requires emissions testing. 

Edited August 8, 2017 by rcb280z

[MrChefur]

Yeah, I read the section and tried what it said. The adjustment nut wasn't doing anything, so I tore down the BCDD and put on another one from my spare parts bin, as well as cleaned the snot out of the throttle body. That fixed that problem.

I'm still having the miss at idle but I've got an appointment tomorrow at a local Z specialist (McKinney Motorsports in temecula, anyone have experience with them?) so hopefully they know what's up.

Edited August 10, 2017 by MrChefur

[rcb280z]

Never heard of them. Let me know how you like them. 

You may have had hole in the diaphragm in the BCDD. 

[MrChefur]

Welp, took it out to smog today and it failed the visual due to blowing white smoke out the tailpipe. This rebuilt motor has 30 miles on it so far, should I just run it more to break it in?

[rcb280z]

I don't recall mine smoking after a rebuild. Maybe initial start up? But that's been several years ago so memory doesn't serve me well. But maybe somebody here can shed some light on it for you.

You should have waited to smog it after your trip to the Z Specialist, maybe?

Did the smog station put it on the sniffer for you to see how the emissions look? And I thought a little smoke from the tail pipe was acceptable for passing emissions. How much is it smoking? 

[MrChefur]

4 minutes ago, rcb280z said:

I don't recall mine smoking after a rebuild. Maybe initial start up? But that's been several years ago so memory doesn't serve me well. But maybe somebody here can shed some light on it for you.

You should have waited to smog it after your trip to the Z Specialist, maybe?

Did the smog station put it on the sniffer for you to see how the emissions look? And I thought a little smoke from the tail pipe was acceptable for passing emissions. How much is it smoking? 

Yeah, I should have waited until after but I had to cancel the appointment. Got a new job and couldn't make it anymore.

Smog station told me they didn't check the sniffer because it failed the visual due to the smoke. It was enough smoke to fill the whole shop. It only smokes under hard acceleration too. I will have to take a closer look at the actual color of the smoke later tomorrow, they told me that the color can indicate what is causing it. I've eliminated a cracked head or blown head gasket so far, but the white smoke leads me to believe it's running super rich. We'll see, I guess.

[rcb280z]

Or you're burning oil. "Whitish" which is more like a blue color would usually indicate oil especially if it lingers. Dissipates fast is coolant.

Hopefully you gave it a break in period when you fired it up after the rebuild. 

Thinking about this, it must really be smoking a lot to fill up the shop. Maybe post some pics and or video.

[Mark Maras]

  Stick your finger in the tail pipe and collect a sample on your fingertip. That and a sniff test will indicate what's coming out of the engine. I think I'd take a look at the plugs and do a compression test too.

[MrChefur]

1 hour ago, rcb280z said:

Or you're burning oil. "Whitish" which is more like a blue color would usually indicate oil especially if it lingers. Dissipates fast is coolant.

Hopefully you gave it a break in period when you fired it up after the rebuild. 

Thinking about this, it must really be smoking a lot to fill up the shop. Maybe post some pics and or video.

The rebuilt engine only has 35 miles on it so far. I was trying to get it smogged as fast as possible since the cops around here are Nazis about driving without smog. Damned if you do, damned if you don't.

How would coolant be getting into the exhaust? It doesn't have a head gasket leak.

29 minutes ago, Mark Maras said:

  Stick your finger in the tail pipe and collect a sample on your fingertip. That and a sniff test will indicate what's coming out of the engine. I think I'd take a look at the plugs and do a compression test too.

I'll pull the plugs again tomorrow but it's put out a consistent 150psi for the 3 compression tests I've done so far. I'll try the finger test too, thanks.

[Zed Head]

1 hour ago, MrChefur said:

Smog station told me they didn't check the sniffer because it failed the visual due to the smoke. It was enough smoke to fill the whole shop..

There doesn't seem to be any smoke in your two videos on Page 1.  Is the smoke a new thing?  Smoke that doesn't smell strongly is usually coolant.  Oil and gasoline smoke both smell like either oil or gasoline.  Are you a smoker?  Maybe get a fresh nose on it, I know smokers can't smell well sometimes.  No offense.

Check your head bolt torques.  Maybe they've loosened or were never properly torqued.

[rcb280z]

12 hours ago, Zed Head said:

There doesn't seem to be any smoke in your two videos on Page 1.  Is the smoke a new thing?

I didn't see any either. Must be something new going on that's why I suggested new videos and or pics.

I'm having a hard time with the "they didn't pass me because of visible smoke". Really need to see some video, not saying it isn't happening, just need to see it.