loose Distributor CAP = Perfect idle

[Zed Head]

On 11/2/2020 at 8:25 AM, ira said:

here is the interesting part, when i loosen the 2 screws on the distributor cap, and raise it up just a tiny bit, the idle becomes perfect (about 800 or so), the engine sounds prefect and the vacuum gauge is solid steady in the green area on 21 or 22.

Seems like you're trying to work on several problems at the same time but some of them are caused by one main source.  If you fix the main source the other problems you're working on might go away.  Trying to fix the secondary problems might actually create new problems, once the main source is removed.  Seems like there's been some distraction.

[Dave WM]

sometimes I get too deep into analysis. Step back, messing with the cap makes it run great, try a new cap and rotor...if that does not fix it then you can get deep into analysis (compression check/fuel/Ign).

[ira]

1 hour ago, Dave WM said:

hmm well 6 look suspect for sure, the rest seem rich. this is where the color tune would come in handy, you can see if its sparking and evaluate the burn.

I would move that #6 injector to another cylinder, get a new set of plugs, and see if the problem follows that injector.

Also I noted your are running a plug I don't recognize. generally speaking NGK standard plugs are run with great success on L motors.

If moving the injector has no effect then clearly there is a spark issue going on.

did you try lifting the plug cap off a bit so there is a spark gap between the plug and the boot? just get it off a tiny bit and see if there is any change in idle.

oh and do a compression test to rule out that as a problem, check all cylinders and look for even pressure.

Right now I am kinda ignoring the "runs better with cap lifted". I don't doubt you its just something that does not have a clear connection yet.

looking for compression, fuel, ignition even on all for now.

 

I hear u guys loud & clear.  i've been keeping discipline.  i was focusing on fuel/injector/air.  All injectors had fuel flow and showed some resistance except#6 (no fuel , no resistance)

Then the Dist CAP thing happened.

I'm about done settings valves to .008 & .010

I cleaned up the spark plug area pretty nice.  the plugs are NGK Platinum Alloy (BPR6EGP7085) 

Is there an injector brand you guys recommend? 

[Zed Head]

What is the gap on those plugs?  Dave suggested that you're not getting spark on #6, not that the injector was bad.  No resistance on your injector would mean that it's not going to open.  But it's hard to see how you could get a perfect idle on 5 cylinders. 

There's no clear path to follow, just a bunch of odd things going on, that don't really fit to define a problem.

Did you already replace injector #6 once, see below?  If so, did you get a turbo injector?  Another random bit...

2 hours ago, ira said:

Plug #6 received a new injector.  

 

[ira]

1 hour ago, Zed Head said:

What is the gap on those plugs?  Dave suggested that you're not getting spark on #6, not that the injector was bad.  No resistance on your injector would mean that it's not going to open.  But it's hard to see how you could get a perfect idle on 5 cylinders. 

There's no clear path to follow, just a bunch of odd things going on, that don't really fit to define a problem.

Did you already replace injector #6 once, see below?  If so, did you get a turbo injector?  Another random bit...

 

the gap is about .035 or .036 on the new plug and bout .037 on the old

the new injector is for turbo as per attached pic.  

my understanding that an injector is support to have about 16ohm of resistance.  my orig#6 has zero.  its as if things are shorted on the inside

let me finish setting the valves back to a tighter spec (8 & 10) since that's how they were originally.

hopefully that will at least clear up the Rich part 

yeah no kidding the idle is perfect.  i left it running an hour while cleaning the garage.  no missing or popping or chocking at all

is there a specific injector link you folks recommend?

 

[ira]

According for FSM, gap needs to be .039-.043

 

[Zed Head]

Your injectors are about 2.5 ohms resistance, not 16.  Make sure you're getting a good measurement.  Your picture of #6 looks like a wet plug that was getting fuel but no spark.

[siteunseen]

I'm late to the party but there's some oily plugs in some of your pics. I don't know what a reason would be so I'm no help. Sorry.

[ira]

1 hour ago, Zed Head said:

Your injectors are about 2.5 ohms resistance, not 16.  Make sure you're getting a good measurement.  Your picture of #6 looks like a wet plug that was getting fuel but no spark.

Oh i see, ur referring to testing the actual terminal.  i was referring to resistance on the actual injector  between its positive and negative lead.  all the other injectors were reading some Ohms (around 16) but not mister#6

gonna increase spark gap to at least .039 and see how it goes now that valves are set a lot tighter

 

 

[ira]

1 hour ago, siteunseen said:

I'm late to the party but there's some oily plugs in some of your pics. I don't know what a reason would be so I'm no help. Sorry.

Nice Z bud..

enjoy the party...

the oil was due to loose valve cover screws. its all cleaned up now

[Zed Head]

17 minutes ago, ira said:

Oh i see, ur referring to testing the actual terminal.  i was referring to resistance on the actual injector  between its positive and negative lead.  all the other injectors were reading some Ohms (around 16) but not mister#6

gonna increase spark gap to at least .039 and see how it goes now that valves are set a lot tighter

No, the 2.5 ohms is across the injector terminals, on the injector.  I copied the other part over just to show that it was for the turbo's ECCS, not the NA system.  All of the injectors, NA and turbo, measure about 2.5 ohms.

Good luck.  

[ira]

29 minutes ago, Zed Head said:

No, the 2.5 ohms is across the injector terminals, on the injector.  I copied the other part over just to show that it was for the turbo's ECCS, not the NA system.  All of the injectors, NA and turbo, measure about 2.5 ohms.

Good luck.  

got it.

so for sure the new inject#6 isnt participating at all. same behavior w orig injector.  when i remove harness engine remains the same.  

i did swap harness connections around w #5.  same results on injector #6.

injector #5 also remained functional and when harness removed, engine would misbehave

tmrw i will try to loosen fuel rail and watch the injectors spray.

unless anyone has a better way to rule this out

take care guys & tnx again!