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Discussion Starter #1
I purchased a 10th ae 280zx about 6 months ago. Body was perfect, interior was major rough (nevada car), engine was obviously not cared for the way it should have been, but ran good none the less. Since then I have painted & lowered the car, along with redoing about 70% of the interior. Now I am starting to dive into the engine. Here is the problem, I believe the car is running way too rich. Here is a list of the symptoms:

1. Bad mileage
2. Dry carbon flakes on the spark plugs. Lots of carbon. Carbon, carbon
3. Dirty smoke when I step on it over 3000RPM
4. Hard to start no matter when (about 5 cranks)
5. Dieseling
6. Very pungent exhaust. Makes your eyes water.

Once started the car idles relatively smooth. It seems to have decent power, but not like my 81 z I had. There is no hesitation and power keeps climbing.

Now, here is what I have done so far.
1. Cleaned all fi connections
2. Clamped off cold start injector to see if it still ran rich......Yep.
3. New Distributer
4. New coil
5. Compression Test 135 ft/lbs +- 10
6. Tested Fuel Pressure
7. New Fuel Pressure Regulator
8. New injectors
9. Tested plug wires
10. Tested temperature sensors (within range) OK
11. Tested AFM (within range) OK appears to be functioning properly
12. New Battery
13. Changed oil and filter

I know that something is wrong, I am just having trouble finding it. Any help would be appreciated. It seems like it is something major wrong which should be easy to find right?
 

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Change out your smog sensors, caty look for oil seeping into your exhaust manifold that will cause smoke...

Just changing those few things will improve milaege and performance in the car...

Is your starter bad? Put some new NGK plugs and wire set...

I can't think of too much else, your symtoms sounded kinda like mine when I pulled it out of the junk yard...
 

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Discussion Starter #5
Thanks for the ideas. Some 1980 z's did not have 02 sensors, mine is one of them. How did you fix your junkyard salvage?
 

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Re: What you could I do next..Long

3. Dirty smoke when I step on it over 3000RPM

Check your Throttle Position Sensor

4. Hard to start no matter when (about 5 cranks)

Put a fuel pressure gauge between the fuel filter and the upper fuel rail. Remove the small gauge wire from the starter solenoid. Turn the key to "start" and hold it there for 5 seconds. Do you hear the fuel pump run and then stop when you release the key?

The pressure should build to 42 PSI and stay there when the key is released.

5. Dieseling

What do you mean here? Engine continues to run after it is shut off? Check timing. What grade of gasoline are you using? 91 or better?

3. New Distributer

New from where? Or a rebuild?

Please read:

http://www.zcar.com/forums/read.php?f=1&i=229859&t=229699

I hit two Dizzy's this year where the screw holding the vacuum advance rod to the breaker plate assembly was too long and it would bind. Rebuilds!

7. New Fuel Pressure Regulator

With the engine at idle the fuel pressure should be 32 PSI, with 16 inches of vacuum on the FPR vacuum port. If you have a vacuum leak and have less vacuum at the port the fuel pressure will rise. I have a exhaust manifold leak on # 1 cylinder and it is now starting to eat its way to the # 1 intake gasket. Each time # 1 cylinder does an intake stroke the vacuum gauge drops and the fuel pressure gauge goes up.

8. New injectors

From where? What was the part # and brand? I got a set of 6 from my parts place and when they arrived they were for the turbo. Checked their system for the turbo injector part # and it was the # for the N/A. Their order system had them reversed.

Finally, put a vacuum gauge on the intake manifold, at idle it should be at least 16 inches and not fluctuate. What does it read?

Spray all of your vacuum hoses with WD40, with the engine running, and if the idle speed changes or the vacuum gauge changes you found a vacuum leak.

Have you checked your intake / exhaust valve clearance?

Wayne Monteath
Masham, Quebec.
 

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Discussion Starter #8
Re: What you could I do next..Long

Thank you all for your help. I will keep you updated as the diagnosis progresses.79-280-ZX wrote:
 
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