Rough idle when cold - Running rich

[Pochie45566]

New known working AAR has been installed. However the same issue remains. I thought it just may be in need of adjustment also? 

Here is my adjustment process: Open up stone cold engine, remove AAR, hold slider open, loosen adjustment nut, push slider back further than original position, tighten adjustment nut. But the AAR moves back to its original position as if nothing was changed. 

Adjusting the idle fuel mix screw on the AFM doesn’t seem to do anything and I don’t think a vacuum leak is causing this because would that not be a fast idle? And it runs great and idles about perfect around 700 when warmed up. If I remember right, vac leaks after the throttle blade cause a lumpy low idle and ones before cause a high idle. Here’s a photo of my AAR slider after being stuck in the freezer for a good while. 

Should I be looking at ignition now? Thanks for all the guidance, I’m enjoying learning about all of this. 

[Pochie45566]

There are these two hoses, one coming from the top of the rad and the other going to the firewall that are not attached to anything, not sure what they’re for. one going into the firewall is on the left (in both photos). Rad one should do anything but also confuses me because it’s not in the FSM diagrams. Then again it is a new rad. The hose on the left I can’t find in any diagrams or photos either. Probably unrelated but just shooting a shot. 

[Dave WM]

AC hoses

[Zed Head]

55 minutes ago, Pochie45566 said:

 However the same issue remains.

 it runs great and idles about perfect around 700 when warmed up. 

Should I be looking at ignition now?

I'm not sure what the issue is now.  Is it a low idle speed when cold?  

You haven't confirmed that the AAR power circuit is working.  The AAR has only one purpose - to raise the idle speed of the engine when cold.  If you're careful you can connect the two pins in the AAR to a battery and see if it moves.

There is a part of the ignition system that raises idle speed, very slightly.  The second pickup coil in the distributor.  The AAR raises idle speed first, immediately, then the second pickup coil keeps it slightly higher until the engine is fully warmed up.  Do you have a two pickup coil system?  

[Pochie45566]

11 minutes ago, Zed Head said:

I'm not sure what the issue is now.  Is it a low idle speed when cold?  

You haven't confirmed that the AAR power circuit is working.  The AAR has only one purpose - to raise the idle speed of the engine when cold.  If you're careful you can connect the two pins in the AAR to a battery and see if it moves.

There is a part of the ignition system that raises idle speed, very slightly.  The second pickup coil in the distributor.  The AAR raises idle speed first, immediately, then the second pickup coil keeps it slightly higher until the engine is fully warmed up.  Do you have a two pickup coil system?  

Maybe a more detailed description of the issue will help. And I do not have a secondary pickup coil if I’m correct  

Upon cold start it idles at 1k for 1-2 seconds then starts to drift down to around 600, bogs, and surges. Once warmed up the idle sits at 750 and runs perfectly with no problems at all.  It has no problem starting in the cold at all, almost always the first crank. 

I have 12.5 volts at the AAR connector and the AAR does close slowly when voltage is applied. Shouldn’t it just be a matter of adjusting the AAR? But it doesn’t seem to adjust or I just don’t know how to do it. 

33 minutes ago, Dave WM said:

AC hoses

Thanks, silly mistake, this is starting to get at my nerves and I forgot I didn’t have AC for a minute ?

Edited November 19, 2018 by Pochie45566

[Zed Head]

 

3 minutes ago, Pochie45566 said:

Upon cold start it idles at 1k for 1-2 seconds then starts to drift down to around 600, bogs, and surges. Once warmed up the idle sits at 750 and runs perfectly with no problems at all.  It has no problem starting in the cold at all, almost always the first crank. 

I have 12.5 volts at the AAR connector and the AAR does close slowly when voltage is applied. Shouldn’t it just be a matter of adjusting the AAR? But it doesn’t seem to adjust or I just don’t know how to do it. 

I overlooked the fact that you have a 1978.  They don't have the second pickup coil.

Have you confirmed that the hoses are actually open?  So that air can flow through the AAR.  It should stay partially open for about 5 minutes.

My vague memory of adjusting an AAR is that the plastic terminal end would twist.  Maybe I'll go dig one up to verify.  But as I recall, I twisted the connector end until the opening was open the proper amount and it also fully closed after battery voltage was applied.  Then I glued the connector, which is actually connected to the heater mechanism, to the metal body.  I think that they can come loose, as Blue showed in his Tech Tip.  Grab the end of yours and see if it twists.

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

 

[Pochie45566]

32 minutes ago, Zed Head said:

 

I overlooked the fact that you have a 1978.  They don't have the second pickup coil.

Have you confirmed that the hoses are actually open?  So that air can flow through the AAR.  It should stay partially open for about 5 minutes.

My vague memory of adjusting an AAR is that the plastic terminal end would twist.  Maybe I'll go dig one up to verify.  But as I recall, I twisted the connector end until the opening was open the proper amount and it also fully closed after battery voltage was applied.  Then I glued the connector, which is actually connected to the heater mechanism, to the metal body.  I think that they can come loose, as Blue showed in his Tech Tip.  Grab the end of yours and see if it twists.

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

 

 I grabbed my old one and twisted it, a little resistance. Now the slider doesn’t really want to turn. There’s only really 180 degrees of motion for that thing to turn without feeling like it’s going to snap. Which makes sense, the bi metal is just flat. But when it is fully turned clockwise, the slider is open say 1/3. Which isn’t much more than it was originally. 

But ive never adjusted one like this before, tell me your results of adjustment on yours  using that method when you have a minute. 

[Zed Head]

My "adjustment" was just putting a broken one back to where it had been.  They're not supposed to twist.

Whatever parts you're moving, if it's open at 68 F (not freezer temperature), and closes after about 5 minutes of 12 volts, it's good.

I forgot to copy Nissan's chart in before.  EF-18.

[Dave WM]

have you confirmed the water temp sensor resistance at the 36 pin connector. also the TPS again a the 36 pin connector. also the air temp sensor same deal at the 36 pin connector. The AAR is pretty easy to check, so you should have cleared that by now.