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loose Distributor CAP = Perfect idle


ira

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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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