loose Distributor CAP = Perfect idle

[ira]

1 hour ago, Zed Head said:

You said that you got about 130 psi in your other post.  So, we can't really tell what's going on.  A list of all six pressures would be good.  

 

the dry test across all cylinders was 130

1 hour ago, dutchzcarguy said:

no. If inj.#6 works thats fine.

Now you say #6 compression is 90 going to 45 psi..thats the problem.. smells like stuck valves..

yeah, the dry comp test across all was 130.  but when car running, #6 would jump quickly to 90 and no more, it will drop down to 45. if i add little rpm it will fluctuate between 0 & 35.  i did same test on #2.  i get 90 at start, then 50.  if i add some rpm it fluctuates at a much higher range than #6.  i think it was between 40~80

i will test the remaining ones today hopefully

Q, would you know if the 82 280zx considered a GDI (Gasoline Direct Injection) into combustion chamber or is it spraying into intake? it will dictate how i go about cleaning attempt to remove an carbon build up that may be causing valve to get stuck

 

[dutchzcarguy]

5 minutes ago, ira said:

would you know if the 82 280zx considered a GDI (Gasoline Direct Injection) into combustion chamber or is it spraying into intake?

Oeps..  It's not a modern petrol car.. nor a diesel..  It sprays 2 times per cycle (of 2 rotations) into the intake manifold!  

[ira]

3 hours ago, dutchzcarguy said:

Oeps..  It's not a modern petrol car.. nor a diesel..  It sprays 2 times per cycle (of 2 rotations) into the intake manifold!  

with that being said...any one can help with DIY? it be nice to know which can to buy and how to best conduct this

how many of you did this as part of their maintenance?

[Zed Head]

I've never heard of the "running compression" test.  I'm not sure that's a valid test of anything.  The throttle valve will be closed and the intake manifold under vacuum.  Edit - The Google says it's a thing.  Haven't dug in to it but I think you still need to compare cylinders, not just do one cylinder.

Your "normal method" test results look good.  I don't really see a problem being described.  Even cylinder pressures, runs well, gets in to boost, etc.  What is wrong?

Edited November 6, 2020 by Zed Head

[ira]

12 minutes ago, Zed Head said:

I've never heard of the "running compression" test.  I'm not sure that's a valid test of anything.  The throttle valve will be closed and the intake manifold under vacuum.  

Your "normal method" test results look good.  I don't really see a problem being described.  Even cylinder pressures, runs well, gets in to boost, etc.  What is wrong?

noted. 

so what would cause plug#6 to be wet and diff from others.   Could that be carbon buildup on that valve? if yes how to best clean that?

what causes inj6 to have no impact on engine when unplugged (if Distributor cap is tight) and have little change in engine sound when cap is a loose?

[dutchzcarguy]

18 hours ago, Zed Head said:

I've never heard of the "running compression" test.  I'm not sure that's a valid test of anything.

😂😂 I also thought what a creative test .. 😂

17 hours ago, ira said:

what causes inj6 to have no impact on engine when unplugged (if Distributor cap is tight)

You need to stop with unscrewing that cap.. it has to be tight on the distr.   Buy some new cap ( for a D6K81-07 turbo distributor!) and leads (if not already done.)  those are old..

Inj. 6 has no impact on engine.. you mean when you unplug it (while running) there is no fall in rpm's..   Then clearly something does not work properly (yes you sayd you saw it spraying.) But the compression is'nt high enough or the spark is to weak. The plug is wet because there is no combustion..

Did you check what type of distributor you have? you need a  D6K81-07  distributor and.. i bet you have the wrong one on there.. type is on the side of it on the aluminium part/shaft..

[ira]

1 hour ago, dutchzcarguy said:

😂😂 I also thought what a creative test .. 😂

You need to stop with unscrewing that cap.. it has to be tight on the distr.   Buy some new cap ( for a D6K81-07 turbo distributor!) and leads (if not already done.)  those are old..

Inj. 6 has no impact on engine.. you mean when you unplug it (while running) there is no fall in rpm's..   Then clearly something does not work properly (yes you sayd you saw it spraying.) But the compression is'nt high enough or the spark is to weak. The plug is wet because there is no combustion..

Did you check what type of distributor you have? you need a  D6K81-07  distributor and.. i bet you have the wrong one on there.. type is on the side of it on the aluminium part/shaft..

on the distributor i can read 22100 p9500

as well as D6P81-02 2503

upon google search it showed the below

https://www.nissanpartsdeal.com/parts/nissan-distributor~22100-p9500.html

Edited November 7, 2020 by ira

[dutchzcarguy]

1 hour ago, ira said:

D6P81-02

Sure it's a P  not a K?  wrong distributor? coul be... over here in europe it's the K version only..  (In serv.man. i see no part number because there are more variations)

Number at the end is maybe not so important 02 or 07 .. i don't know..  Maybe someone with a 280zx turbo could chip in.. 

[ira]

53 minutes ago, dutchzcarguy said:

Sure it's a P  not a K?  wrong distributor? coul be... over here in europe it's the K version only..  (In serv.man. i see no part number because there are more variations)

Number at the end is maybe not so important 02 or 07 .. i don't know..  Maybe someone with a 280zx turbo could chip in.. 

pretty sure it's a P

here is a good site for parts guys.. https://www.rockauto.com/en/catalog/nissan,1982,280zx,2.8l+l6+turbocharged,1209361,ignition

 

[Zed Head]

Check the engine's grounding.  Maybe it's poor so the gap across the spark plug electrodes is not the path of least resistance.  Actually, check the resistance of the head to ground, the battery negative post or the alternator case, or both, since the head is what the spark plugs ground to.  Just looking for odd reasons that lifting the cap has an affect. 

But, a new clean cap is probably the best first step.  The turbo distributor uses the two screws to lock down so you can't really get it mixed up with NA.  The local parts stores sell the same parts as Rockauto.  Just a little bit more expensive. Get new wires also.

https://www.oreillyauto.com/shop/b/ignition---tune-up-16776/distributor-cap---rotor-16854/distributor-cap-12506/a0b4d83dd803/1982/nissan/280zx?q=distributor+cap

Edited November 7, 2020 by Zed Head

[ira]

17 hours ago, Zed Head said:

Check the engine's grounding.  Maybe it's poor so the gap across the spark plug electrodes is not the path of least resistance.  Actually, check the resistance of the head to ground, the battery negative post or the alternator case, or both, since the head is what the spark plugs ground to.  Just looking for odd reasons that lifting the cap has an affect. 

But, a new clean cap is probably the best first step.  The turbo distributor uses the two screws to lock down so you can't really get it mixed up with NA.  The local parts stores sell the same parts as Rockauto.  Just a little bit more expensive. Get new wires also.

https://www.oreillyauto.com/shop/b/ignition---tune-up-16776/distributor-cap---rotor-16854/distributor-cap-12506/a0b4d83dd803/1982/nissan/280zx?q=distributor+cap

Actually last week i added a ground cable link from the manifold to the battery negative because i didnt like the reading test i did between batter & chassis main ground.  it doesnt look like it made much of a difference but its a good thing to do regardless.

i obtained a CRC electronic cleaner and ive been going through connectors when ever possible

waiting on new CAP & Cables to arrive.

 

i made the spark plug gap about .4  is that ok? i think originally they came as .35.  should i make it bigger? the FSM gave a range of .39~.43

[dutchzcarguy]

23 minutes ago, ira said:

i made the spark plug gap about .4  is that ok? i think originally they came as .35.  should i make it bigger? the FSM gave a range of .39~.43

Your talking inches right? then you mean 0.04!   (in mm it's 1.0-1.1mm)  so 0.04 x25,4mm is 1.016 mm is OK.