Cant find the solution no matter how much searching I do

[L3BOWSKI]

My Z has been occasionally making a "popping" sound when accelerating, or going uphill. sometimes there are a few in rapid succession and sometimes its just one. This is not my video but this is the exact sound that I am hearing. I have all new injectors. I just want to know where to start before i start buying new parts hoping something will fix it. All the vacuum lines are good. I have been googling as much as I can to try to find a solution. Thank you for your time. 

 

[Zed Head]

You should give a little more information about your car than "Z".  Apparently it's a 280Z since it has injectors.  The noise is called "front-fire" or intake popping among other labels and it is pretty common with the 280Z's.  Not clear why but the EFI system runs lean in some cases.  The best fix that many of us have used is to cause the system to add a little extra fuel across the air flow range, using extra resistance on the coolant temperature circuit.

Atlanticz has a great description.  http://atlanticz.ca/zclub/techtips/tempsensorpot/index.html

BUT.  This is a fix for after you've confirmed proper fuel pressure, and ignition timing, and valve lash, etc.  I'd give it a very thorough tune-up first.

[siteunseen]

Sounds like a lean condition, a vacuum leak somewhere, if it's popping through the engine compartment.  In 1977 they had a recall on the EGR coupler to the rear of the intake.  If that wasn't fixed, mine was not, the exhaust from the EGR tube will rot out the aluminum intake leaving a hole for unmetered air to enter causing the air/fuel mixture to be lean.  You can borrow a vacuum gauge from a parts store and see what kind of vacuum you're pulling.

http://atlanticz.ca/zclub/techtips/airleaks/index.html

This is just for explanation reasons, don't mess with the AFM.

Here you can see the AFM bypass adjustment screw. It is used to close a passage under the primary AFM passage.
This passage is primarily used to vary the air to fuel ratio at idle. The screw controls how much "extra air" bypasses the AFM.
Closing passage is accomplished by turning the screw CW.
btw When the intake "pops" aka front fire usually due to running lean;. the energy passes through this passage. 
If it is closed off, the energy will damage the flap.

 

[siteunseen]

Zed you type faster than my finger pecking.

To check the recall area for rotted aluminum hold a mirror under where the red arrow is in my picture, quick and easy to find but a whole can of worms if it's damaged.

[jonathanrussell]

This is a total guess without really measuring and diagnosing the efi system but the sound is very similar to what I heard in my 280 when the airflow meter flap was stuck open....due to being bent....and bent due to a previous backfire.

[L3BOWSKI]

I believe my vacuum is okay as I did the test where you remove the oil cap to see if the engine sound changes, and mine nearly died when i removed the cap. Sorry, I should have stated mine is a 1976 280z so I don't believe it has the EGR coupler issues. I will look into the timing and research how to adjust valve lash. Thank you for the replies. 

[siteunseen]

If it nearly died when you removed the oil cap you have more air getting in somehow. Mine drops around 200rms when I take the cap off but still runs. I've seen videos of them running with the whole valve cover off. 

My car is a 9/'76 and had the egr hole. The recall came out in '77.  Try and be more acceptable of our recommendations,  you are asking for help, not the other way around.

[siteunseen]

http://www.classiczcars.com/topic/56918-egr-delete-1980-zx-na/?do=findComment&comment=510901