77 Z not starting anymore - Conductivity results

[Labubre]

Hi

Engine cranks but not start.

This 3 days after collecting the car at the garage for wheel/tire change. Guy told me "engine is running on 5 cylinders".

Did not notice, but remember now 8 monthes ago that another garage owner change the sparkplugs...may be one was brand new but dead.

Car went fine even if driven less than 200 miles or so.

Could a dead sparkplug flood the engine with fuel with time? A possibility to explain why not starting anymore???

Anyway, did the continuity test and here are the results:

 

Except for the water temperature sensor, everything's seems OK.

Anyone has a concern regarding these results?

Anyone got the bright idea to collect these data on a well running Z?

Thanks for the support

 

 

 

 

 

 

 

 

 

 

[siteunseen]

I would buy a set of plugs, $10 and make sure the wires are in good shape and the right order.

The cold start valve could be dumping fuel in also?

[superlen]

Check that the connectors for your coolant sensor and thermotime switch aren't reversed...perhaps the shop owner had them all off looking for a problem and connected them back up incorrectly. The connectors will interchange no problem. They are right next to each other. While they are marked, they aren't marked clearly. If they are dirty and covered with a little grease/oli they are easy to get backwards.

The coolant sensor is important to the fueling map, so if it's not connected properly, or the connections are old and dirty, you will have problems.

Len

 

[Dave WM]

Start with the basics, pull a plug, lay it on the valve cover, connect the plug wire, crank the engine, does it spark?

If it does double check the firing order.

Next, look at the plug, does is smell of gas? wet with gas? completely dry? install a fuel pressure gauge crank the engine does the pressure shoot up to 36-38 psi?

I am assuming compression is ok (ok maybe I should not) so you have to narrow it down to spark or fuel.

[Labubre]

Thank you guys!

@siteunseen: sparkplugs are 8 monthes old.

@superlen: I see thermotime and temp sensor are looking the same. But shop owner did not touch anything. He just notice engine was running on 5 cylinders. Told me 1 injector might not work.

@Dave WM: spark test to be done tonight. Plug wire set has been installed brand new in 2017. New plugs in January. This is last intervention on plugs. Since then, 200-300 miles on it. WIll check plugs condition tonight and if there's a spark.

Also done 8 month earlier: fuel pressure regulator change. I also know my auxiliary air regulator to be dead (cold start in winter need accelerator support for idle till engien is hot)

Tested last night: fuel pump is OK with following test: ingintion "key ON" + AFM flap actuated manually = "bzzzz" :)

Will let you know about tonight tests.

 

[Labubre]

By the way, with ingnition key on "ON" position, i do not hear anymore the "click, click, click..." sound before staring the engine

What's this sound related to?

EFI relay?

I've changed the 4 fusible link on the main bracket relay near the battery. But going out from the "+" wire of the battery there are some connectors i do not know the use yet.

[Dave WM]

Assuming you have spark and its to the correct plugs, and assuming the fuel pressure is correct your next test will be to listen to the injectors to see if they are clicking while cranking. That will let you know the ECU is working. Use a mechanic stethoscope or even just a long screw driver with the tip touching the injector body and the other side if the LONG screwdriver held up to your ear. You should here it while the engine is being cranked by the starter.

 

[Labubre]

Today

Change of all the sparkplug

Test continuity 2 using voltmeter as per FSM

2)1) Revolution trigger signal: OK 12,3V

2)2) Power line circuit: OK 12,36V

3) Injectors & dropping resistor

3A cylinder 4 = OK 11,5V

3B cylinder 1 = NOK 0V

3C cylinder 5 = 11,5V

3D cylinder 6 = Ok 12,36V

3E cylinder 3 = OK 12,35V

3F cylinder 2 = NOK 0,5V

If i understand correctly, i have injector 1 & 2 are in trouble.

What i don't know from is test is that: aren't they getting power OR are they dead?

 

[Labubre]

oh!

Engine still not starting...

[Labubre]

Part II of continuity test with volmeter:

1) "revolution trigger signal" -> doit correspondre au rotor de l''allumage: test OK/ 12,3V
2) "Power line circuit" -> test OK / 13,4V
3) "Injector & dropping resistor"
3A - Cylindre 4 - 11,5V
3B - Cylindre 1 - 0V

3C - Cylindre 5 - 11,5V
3D - Cylindre 6 - 12,35V
3E - Cylindre 3 - 12,35V
3F - Cylindre 2 - 0,5V

So, something wrong on Cylinder 1 & 2.

Have to check infector and dropping resistance.

Will conduct these test on Wednesday and let you know.

I am moving slow....

 

Part III of continuity test requires to disconnect "S" terminal of starter...Can somebody tell me what terminal this is???

1 single wire connected to "S" terminal or several?

Thanks

 

 

[superlen]

The S wire is the small wire that fires the starter solenoid.  When you turn the key, +12v is routed to this wire (again it's small like 14awg) and a small amount of current flows to the solenoid and energizes it. The solenoid when fired connects the big battery cable wire (also +12v of course) to the starter motor and the starter motor turns the flywheel.

I'm assuming the test you are trying wants you to turn the key to 'start' but they don't want the starter to actually turn.

Len

[Labubre]

7 hours ago, superlen said:

The S wire is the small wire that fires the starter solenoid.  When you turn the key, +12v is routed to this wire (again it's small like 14awg) and a small amount of current flows to the solenoid and energizes it. The solenoid when fired connects the big battery cable wire (also +12v of course) to the starter motor and the starter motor turns the flywheel.

I'm assuming the test you are trying wants you to turn the key to 'start' but they don't want the starter to actually turn.

Len

Thanks Len!