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loose Distributor CAP = Perfect idle


ira

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To add more to the mix, I had an 82 Turbo that ran fine cold, but once warmed up it would run really rough at times.  The ECU was exposed right by my foot.  I accidently bumped the plug going into the ECU and it ran great!  When ever the car would do this I would do this and it ran great.  It was repeatable.

Those ECU plugs have known connectivity issues.  I'm pretty sure there are some guys who have upgraded to the Z31 ECU plugs because of it.  And I'm not talking about upgrading to the Z31 ECU, just the plugs.

Edited by JSM
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7 hours ago, Dave WM said:

disable 6 when cold does it have any effect on idle?

after warm up disable 6 does it have any effect on idle?

swap 6 with 5 repeat test cold and warm

the video did not work for me btw.

Lastly something to consider even when everything is working, the enrichment circuit adds fuel right after startup for a few minutes, this is above the normal CSV and temp sender enrichment.

Its very hard to remote diagnose even if the video worked. You mentioned a strong gas odor, that would make you think its maybe not getting a good spark and perhaps when it leans out some after warm up #6 is just not igniting. the color tune will help with that. put it in 6 observe the color (should be yellow cold) then watch to see if it goes to blue (correct mix) and then dark but for a spark (flame out).

 

the car may run just a tad rougher when idling after fully warm vs when cold just do to the leaner enrichment. I am not talking big differences here, at least on my car that is the way it is. I have thought of adjusting the AFM bypass to see if I can richen up the circuit (presuming that is why its just a tad rougher idle when fully warmed up), but have never bothered to try it as its really minor. The EFI is rather primitive (batch fire, open loop) so its prob setup to pass emissions on the lean side of things.

I don't think the above statement is your issue, just stating my cars operation from cold to fully warm.

 

 

 

 

 

i swapped inject6 w inject 5, and the problem followed. as soon as i unplug harness on any injector engine will act up except on the new injector which i snow in position number 5. 

 

So even though it sprays can it be a bad injector?

Whats next?

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3 hours ago, JSM said:

To add more to the mix, I had an 82 Turbo that ran fine cold, but once warmed up it would run really rough at times.  The ECU was exposed right by my foot.  I accidently bumped the plug going into the ECU and it ran great!  When ever the car would do this I would do this and it ran great.  It was repeatable.

Those ECU plugs have known connectivity issues.  I'm pretty sure there are some guys who have upgraded to the Z31 ECU plugs because of it.  And I'm not talking about upgrading to the Z31 ECU, just the plugs.

Hey JSM, and tnx for sharing.

my ECU was replaced by my trusted mechanic few years ago.  my dad accidently plugged the battery backwards and fried few things. several parts were replaced at that point.  one of which the distributor.

  im pretty confident its a healthy ECU but i don't have a way to prove that.  as for the connectors, they are nicely snug and safely covered.  i dont mind upgrading connectors if u have link for one.

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1 hour ago, ira said:

i swapped inject6 w inject 5, and the problem followed. as soon as i unplug harness on any injector engine will act up except on the new injector which i snow in position number 5. 

 

So even though it sprays can it be a bad injector?

Whats next?

It does sound like that injector is bad.  I would replace it.  Make sure you get a turbo injector.

We might never know what's going on with your distributor cap.

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43 minutes ago, Zed Head said:

It does sound like that injector is bad.  I would replace it.  Make sure you get a turbo injector.

We might never know what's going on with your distributor cap.

i had previously put a link for the injector i purchased and it was for sure fit for the turbo model.  can some one recommend a brand?

 

tnx

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12 hours ago, ira said:

Hey JSM, and tnx for sharing.

my ECU was replaced by my trusted mechanic few years ago.  my dad accidently plugged the battery backwards and fried few things. several parts were replaced at that point.  one of which the distributor.

  im pretty confident its a healthy ECU but i don't have a way to prove that.  as for the connectors, they are nicely snug and safely covered.  i dont mind upgrading connectors if u have link for one.

I would unplug the ECU and check for any corrosion though.  Use some electrical cleaner and spray each connector. Make sure you let it dry well before re-starting.  

I found a bunch of info on the z31 ECU upgrade, but for the life of me I couldn't find just the plug upgrade.  I think it was on zdriver site.  I'll have to keep looking.

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4 hours ago, dutchzcarguy said:

sayd it before.. new does not mean "good" .. the injector is one of the (many?) problems.

i hear ya, but the injector does spray.  so could it be something else in the injector that is malfunction?

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2 hours ago, JSM said:

I would unplug the ECU and check for any corrosion though.  Use some electrical cleaner and spray each connector. Make sure you let it dry well before re-starting.  

I found a bunch of info on the z31 ECU upgrade, but for the life of me I couldn't find just the plug upgrade.  I think it was on zdriver site.  I'll have to keep looking.

im a huge fan of keeping it original but if there is a benefit in upgrading ECU, i wouldn't mind it.  some upgrades are healthy and do increase car safety and efficiency

 

send some suggestions pls

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Guys, anyone knows about the reference signal? i was reading somewhere that there is a 5v signal that must be available at all times.  it's originally an AC signal that comes from the Crank Sensor to ICM, then ICM converts it to a digital Sig that the ECU can benefit from.   i have no clue where i can chk for that on the ZX

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3 hours ago, ira said:

i hear ya, but the injector does spray.  so could it be something else in the injector that is malfunction?

Maybe it got clogged somehow.  You said the problem follows the injector.  Therefore, the injector is probably the source of the problem.  Replacing the injector with a properly functioning injector should remove the problem.  A problem with a single injector is not going to be affected by the CAS signal.

https://www.enginebasics.com/Engine Basics Root Folder/Fuel Injectors.html

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3 minutes ago, Zed Head said:

Maybe it got clogged somehow.  You said the problem follows the injector.  Therefore, the injector is probably the source of the problem.  Replacing the injector with a properly functioning injector should remove the problem.  A problem with a single injector is not going to be affected by the CAS signal.

https://www.enginebasics.com/Engine Basics Root Folder/Fuel Injectors.html

tnx for the reading material.

im on the zCarDepot placing order for injector, CAP, Rotor & new basic NGK plugs.  

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8 hours ago, ira said:

looking to get an Oscilloscope

A good scope cost money on the other hand you just need a simple (analog )scope.. but if your not technical underlaid in electronic systems, i don;t think you will be able to use this kind of equipment..

I took a look but there is changed a lot since the time i bought me a scope..  First was 40 years ago and the last at least 15..   I could use a new one haha.. a handheld one (my last one)  could also be something for you.. but again it took some good education to handle those things.. 

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it be nice if i find one that can help service the old Z plus newer cars.  im a computer geek, so i will figure it out, but i just need help deciding what is suitable for the older cars.

whats specs should i be looking for on an Oscilloscope

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  • 3 weeks later...

Hey folks, hope all is well.

finally i Received the new injector form zcarDepot.  USPS isnt the best choice, it took 2 weeks to arrive.  for $65 i received a very originally looking item with upper and lower seals &clamp. vacuumed sealed package.

i made sure the injector sprays.  started the car with new inject & old cap/rotor.  when removing the power harness on the new injector the engine will immediately start to act up.  so im glad we have a change there.

but the car still has the same issue which is starting to idle rough after a while and not being able to go above 30 MPH.

 

so i went a head and replaced the CAP & rotor with new ones off ebay ( it suppose to be japan made prt) the car ran worse than before. very bad idling.

for the first time ever, when i removed the vacuum hose on the fuel regulator, some stuff came out.  it was almost like a debries or dust like.  im almost certain it wasn't wet or moisture spray .  it only happened once 

 

loosing up the cap doesn't seem to make a diff

not sure if car needs to run for a while to learn about the new injector.  what can i do next?

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last night's weather wasn't much diff than now.  I just started the car again, it idled high around 1300 for a min or 2 , then back down to around 850 for past 15 min.  not seeing rough idle like last night.  will let it go for a little longer to see if it changes.

 

i measured 19 psi on the intake (right off the fuel regulator hose)

 

will post pic of plugs as well.  the cables are new NGK ones as well

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so idle is around 850 still with some missing every few seconds, just like before.

 

as for revving it up, (slowly, gradually or suddenly) today its very smooth with no hesitation or choppiness.  Couldn't take it for spin due to rain (tires not in good shape)

 

i feel its a Fuel air mix issue but not sure where to start.  i dont want to redo the valves clearance again 

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I would start reading from this page in the FSM, below.  The Turbo system has a lot of interconnected parts.  The ECU has lights that flash when it goes in and out of closed loop control.  Closed loop is where the O2 sensor comes in to play.  You could probably watch the light while the engine warms up and see if things change when the light starts flashing.  When you talk about what's going on it would be better to tell what the engine temperature is, instead of a "a while".  Engine temperature controls when things happen.

It's kind of a complex system that takes some real study to understand.  That's why Nissan developed the Analyzer.

Search for cgsheen's comments.  He always recommends Megasquirt.  He knows how the ECCS system works though.

Are you sure the turbo isn't jammed?  Your 30 mph limit sounds like something's blocking your exhaust flow.

image.png

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1 hour ago, Zed Head said:

I would start reading from this page in the FSM, below.  The Turbo system has a lot of interconnected parts.  The ECU has lights that flash when it goes in and out of closed loop control.  Closed loop is where the O2 sensor comes in to play.  You could probably watch the light while the engine warms up and see if things change when the light starts flashing.  When you talk about what's going on it would be better to tell what the engine temperature is, instead of a "a while".  Engine temperature controls when things happen.

It's kind of a complex system that takes some real study to understand.  That's why Nissan developed the Analyzer.

Search for cgsheen's comments.  He always recommends Megasquirt.  He knows how the ECCS system works though.

Are you sure the turbo isn't jammed?  Your 30 mph limit sounds like something's blocking your exhaust flow.

image.png

 

i do have access to the ECCS analyzer for the 1982 Turbo but it has no manual.  i have not been able to locate any

ive seen few nice vids on  Megasquirt.  i dont mind it as long as i know where the issues are!  

Prior to replacing injector, the turbo worked just fine when CAP was raised.  so im sure its not a turbo issue

hopefully when rain stops i can take it for a spin

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