Help - Adding ground locations

[Blitzed]

Hi All,

240z Wiring harness , L28 two questions below on grounds. 

The EFI set-up is complete. Worked with Haltech remotely engine is running but chasing down a vacuum leak. Also having a weird issue with the electronic distributor connection to the ECU. Losing the grounds randomly. 

First questions: Need to add a grounding strap from the chassis to engine block. Why, attempting to move my star ground (all required ECU ground connections) to another point (currently chassis).  Where is the best connection point? The engine bay harness is a stock 73 240Z. Is the chassis ground under the battery box off the harness a good point for a chassis to engine block strap? The FSM manual will not help with this issue, adding ground connections.

Second question: Also running a single coil with igniter (no problems), all the stock 240z coil, distributor, resistor wires have been terminated and secured. Harness is still intact on left front fender. Is the green/white wire (ground) a usable ground wire in from the old harness for a chassis ground?  

Thanks,  

[SteveJ]

22 minutes ago, Blitzed said:

Hi All,

240z Wiring harness , L28 two questions below on grounds. 

The EFI set-up is complete. Worked with Haltech remotely engine is running but chasing down a vacuum leak. Also having a weird issue with the electronic distributor connection to the ECU. Losing the grounds randomly. 

First questions: Need to add a grounding strap from the chassis to engine block. Why, attempting to move my star ground (all required ECU ground connections) to another point (currently chassis).  Where is the best connection point? The engine bay harness is a stock 73 240Z. Is the chassis ground under the battery box off the harness a good point for a chassis to engine block strap? The FSM manual will not help with this issue, adding ground connections.

Second question: Also running a single coil with igniter (no problems), all the stock 240z coil, distributor, resistor wires have been terminated and secured. Harness is still intact on left front fender. Is the green/white wire (ground) a usable ground wire in from the old harness for a chassis ground?  

Thanks,  

First answer...is a question. Are you not running the battery negative to the starter? Stock has the battery negative (4AWG to 2AWG) running to the starter with an auxiliary wire around 10AWG bolted to the firewall. You want a solid mechanical contact to both the starter and firewall with no paint to interfere with the contact.

Second answer...is another couple of questions. What do you mean by terminated and secured? In wiring, terminated means installed at the appropriate location, and secured means you have bundled the wires so they can't get pulled loose. Why are you calling the green/white wire a ground? In the stock wiring configuration with the Key in ON, Battery positive goes to the starter connection point. From there, it goes to the fusible link and to a white wire. The white wire goes to the Ammeter and comes out white/red. The white/red goes to the ignition switch where it comes out on the black/white wire. The black/white wire goes to the ballast resistor and goes to the green/white wire. The green white wire goes back to the tachometer to drive the signal for the tach and comes out black/white. That black/white wire goes to coil positive. When I installed a Pertronix ignitor in my 73, I removed the ballast resistor and connected the black/white from the ignition to the green/white going to the tachometer. That way there was still a signal driving the tach. 

So your questions also drive more questions. Where are you getting the voltage for your coil? Do you still have the stock tachometer? Why are you looking for a ground wire near the coil? What circuits are losing grounds?

[Zed Head]

You can have more than one ground point.  There is a ground wire from the alternator body to the harness which must be attached to battery negative.  And the alternator body is attached to the engine block through its mounting bolts.  And battery negative is attached to the body grounds.  Plus the battery negative is attached to the engine block through the starter  mounting bolt.

Many distributors use the mounting screws as grounds through the distributor body, but also have a separate grounding wire to the body.

You can learn a lot with a meter.

Posting before I look at SteveJ's reply...

[Blitzed]

On 3/22/2022 at 5:54 PM, SteveJ said:

First answer...is a question. Are you not running the battery negative to the starter? Stock has the battery negative (4AWG to 2AWG) running to the starter with an auxiliary wire around 10AWG bolted to the firewall. You want a solid mechanical contact to both the starter and firewall with no paint to interfere with the contact. Yes this is the stock 73 config . all contacts have been cleaned and tested. 

Second answer...is another couple of questions. What do you mean by terminated and secured? Connectors removed, wires heat shrunk and wiring wrapped in the harness (stored). terminated means installed at the appropriate location, and secured means you have bundled the wires so they can't get pulled loose. Why are you calling the green/white wire a ground? In the stock wiring configuration with the Key in ON, Battery positive goes to the starter connection point. From there, it goes to the fusible link and to a white wire. The white wire goes to the Ammeter and comes out white/red. The white/red goes to the ignition switch where it comes out on the black/white wire. The black/white wire goes to the ballast resistor and goes to the green/white wire. The green white wire goes back to the tachometer to drive the signal for the tach and comes out black/white. That black/white wire goes to coil positive. When I installed a Pertronix ignitor in my 73, I removed the ballast resistor and connected the black/white from the ignition to the green/white going to the tachometer. That way there was still a signal driving the tach. You can see my new HEI coil and igniter in the pic. This config did not require any of the stock harness wires on the left fender. Ran a separate ground wire from the star ground point (currently chassis) to the igniter, coil fires and wire tested as good.  

So your questions also drive more questions. Where are you getting the voltage for your coil? Igniter, ECU Do you still have the stock tachometer? yes, works great,  split white wire config (ECU coil power wire one side and a wire directed to the positive side of the coil other side) Picked up the config up from Duffy's post.  Why are you looking for a ground wire near the coil? Would like to ground the HEI coil to the chassis.  What circuits are losing grounds? Purchased a hall effect distributor (ref and sync signals) the distributor is driven by four wires, 12v from the ECU, signal ground from the ECU and two 5v pulse wires from the ECU. Asking about different grounding locations as the engine will start and then not start. All connections and internals on the distributor have been tested by rotating the distributor cap by hand (removed from the engine) verified pluses signals are generated and accurate. When cranking the engine the ECU is not picking up the signals from the distributor, will not start. So I'm chasing down a ground or load issue during cranking.  

 

[Blitzed]

Zed Head,

Alternator has been upgraded with MSA 60 amp with harness adapter. See pic of wiring, assume the ground wire from the stock harness is linked the chassis ground below the battery. I'm not seeing a ground wire to the engine block from the alternator. Not seeing any ground wires to the block other than the battery to starter. 

 

[Blitzed]

Zed Head,

The ECU wiring to the distributor is a shielded cable and the ECU can not handle multiple grounds points on these cables. One side or the other. Currently the ground connection for the main ECU ground is the battery which drives the signal grounds to the distributor and other sensors. All other sensor requiring a signal ground from the ECU function properly and static (non running engine) reads are recognized by the ECU.. Because the distributor requires movement to trigger data on the ECU, it's an issue. 

Believe it's a switch on bad ground (before start) issue as I've tested the distributor pulsing when I connect the distributor to the ECU connector and turn the key to the on position (ECU on) and rotate the distributor rotor, ECU is still not pick up the pulse signals, so a disconnect at power on. All wires in the connector ECU side have been metered as good. 

No fuses blowing, the ECU has two fuses integrated and two relays all good. 

[SteveJ]

The coil is not grounded full time. It is only grounded when it is triggered by the ignition system. It sounds like you are saying that in your configuration the positive is coming from the ECU. I am not familiar with Duffy's car, I have no idea how he wired his ignition or tachometer. If firing when attempting to start is intermittent, verify the Hall effect sensor is working properly and the ignition system is grounding when getting the proper signal from the sensor. It sounds like you have done that already.

What is the resistance from battery negative to the grounding screw in the photo? 

How about resistance from battery negative to the grounding post on the alternator?

Again, if you have the stock connections on the battery, you have a large gauge wire to the starter and a smaller gauge wire (around 10AWG or so) going from the battery negative to the firewall. If you don't have the second wire, your grounding could be compromised.

The starter is firmly bolted to the bell housing which, in turn, is firmly bolted to the block. The cable is the weakest link in that chain. The next weak link is corrosion on fasteners or between components.

Also, don't be afraid to take a resistance reading between the engine block (unpainted surface like the bolts around the timing chain cover) and the shock tower studs. Have the meter on resistance, not continuity. You want the number, not a buzzing.

[Zed Head]

2 hours ago, Blitzed said:

All other sensor requiring a signal ground from the ECU function properly and static (non running engine) reads are recognized by the ECU.. Because the distributor requires movement to trigger data on the ECU, it's an issue. 

Are you using the word "ground" correctly?  Or understanding how the ignition system works?  No offense.  It sounds like you're saying that the ECU is not picking up the distributor trigger.  Is it the factory variable reluctance (VR) trigger?  What is under the distributor cap?  Stock parts or aftermarket parts?  A picture would be good.

The VR trigger does not use a ground it uses two wires that transmit an alternating current wave form.  It's not uncommon to have triggering problems with the aftermarket engine management systems or ignition systems, like MSD's.  Some trigger systems are set up for Hall effect triggers as an option.  People get them mixed up sometimes.  Might be worthwhile to show your wiring scheme. 

The distributor ground might not be important in your case, although I think that it migth serve the purpose of dissipating static charge or stray spark plug wire spark.  It's definitely important with a points system.  

[Blitzed]

Hi All,

No offense taken, the conversion to Haltech ECU and EFI was what is was intended, a learning experience. Was not and still not and expert but working my way through the curve to novice.  

Yes, main obstacle is the ECU is not recognizing the distributor pluses. It did and operated flawlessly, 6 months ago ran the ignition and timed with the SU carbs.

I've added additional parts since them fuel pump and sensors. So something went sideways with the additional function. As mentioned all other parts work, pump runs, 02 sensor has readings, TPS sensor functions, intake air sensor reads, coolant temp reads, MAP reads, CAN gauge in the dash and all stock gauges all function.

Question about the distributor, pic, parts and functions. I start a new thread here, you can see all the parts and diagrams "Haltech wiring ignition basic questions".  

Thanks I'll take some meter readings and report back. 

[Blitzed]

VM set 20k omhs and neg battery post. All connections, chassis bolt (in pic) and on the firewall, alternator neg, block, started neg cable bolt all zeroed out. Since the engine will not start, The only dynamic test I can do is ignition on, fuel pump running. 

Same VM setting 20k

Chassis bolt below the battery, 22, alternator neg bolt 24, block 20, star grounding connectors, 12. 

When I touch the signal ground wire for the distributor connector with the ignition on, bounces, 4-24 randomly. Is this common for a signal ground?

One main ground wire from the ECU to the battery - (input)  All signal ground wires for the components are ECU outputs and are tied in the main harness to pin 10 battery - input.  

[SteveJ]

Those readings seem high, though it could be, in part, due to technique. 

Watch this video of me taking resistance readings on the grounding points and battery.

 

If it was working well before you did the work, the first thing to do is to check over what you touched to see where you messed up. That's my starting point on a lot of troubleshooting.

[Captain Obvious]

3 hours ago, SteveJ said:

Watch this video of me taking resistance readings on the grounding points and battery

Wow... "HoldPeak" meters, huh? So they get to use the abbreviation HP in all their products and model numbers?

How convenient....    

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