83 280zx non turbo 5 speed runs rich. heavy black smoke/ soot coming from exhaust. rough idle before warm up. how do i fix this problem?

Asked by Dec 03, 2011 at 03:55 PM about the Nissan 280ZX

Question type: Maintenance & Repair

83 280zx 5 speed, non turbo coupe. car has a rough idle at start up which smooths out as car warms up. exhaust is very black and sooty. car is running rich. spark plugs also covered in black sooty carbon. car is stock except for cold air intake. what is causing this problem? what should i check or adjust? thanks.
rod

2 Answers

3,405

Need a little more information...mainly, when did this start? Did it start after you put on the Cold Air Intake? If yes, check any related sensors first for condition and proper connection... MAF and IAT..... very important to mixture control. If there's no connection with the Cold Air Intake, there's a few possibilities and it would take some diag work to narrow it down.... Stuck EGR valve is one possibility. Another possibility is if the fuel pressure regulator operates on vacuum with a diaphragm, sometimes the diaphragm will blow which will increase the fuel pressure and also allow fuel to be sucked through the vacuum line directly into the intake. I'm not familiar with the fuel delivery system on the old Nissans......I'm assuming it's an early generation fuel injection setup though...?

30

on these late models check all your vacuum lines they are notorius for hardening around the nipple hook ups and cracking there i had the same problem on my 83 turbo if left to long it can cause damage to the engine one trick is get some rubbing alcohol and start car pour some of it in a small cup 4oz. about disconnect a vacuum line to the intake manifold leaving it connected to the manifold allow the hose to slowly suck it in with out stalling the engine and plug it with your thumb this will clean you maybe running to cold of spark plugs

Your Answer:

Shortcuts

Nissan 280ZX Experts

  • #1
    F_O_R
    Reputation
    80
  • #2
    dandyoun
    Reputation
    50
  • #2
    enginecreator
    Reputation
    50
View All

Find great deals from top-rated dealersTM

Search

Related Models For Sale

Used Nissan 240SX
1 listing
Used Nissan 300ZX
2 listings
Used Nissan 350Z
26 listings starting at $8,888
Used Nissan GT-R
35 listings starting at $79,987
Used Nissan 370Z
11 Great Deals out of 182 listings starting at $14,900
Used Ford Mustang
43 Great Deals out of 1,782 listings starting at $4,995
Used Toyota Supra
33 listings starting at $64,990
Used Subaru Impreza WRX STI
3 Great Deals out of 79 listings starting at $12,995
Used Chevrolet Camaro
35 Great Deals out of 1,112 listings starting at $9,950
Used Honda Civic
149 Great Deals out of 6,139 listings starting at $1,700
Used Mazda RX-7
1 listing

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use. Content will be removed if CarGurus becomes aware that it violates our policies.