3.2 Speed & Reference Sensors...both bad at the same time...

[mysocal911]

Originally Posted by mziggy16

It’s not the DME relay. We swapped in my old, functioning, relay.

Pump and Regulator are getting 36psi to the rail.

Could be injectors. What are the odds of ALL of the injectors being stuck? Would assume it’s power delivery to the injectors rather than all of them being stuck.

And then there’s the DME ECM…is there a way to test this without swapping in a new one?

Read here; 911 3.2 No-Start Troubleshooting

[phelix]

The injectors need a good earth - were any disturbed during the engine removal?

[76FJ55]

Originally Posted by phelix

The injectors need a good earth - were any disturbed during the engine removal?

The injectors should be supplied a constant 12V from the DME relay. the ground path is controlled by the Motronic DME to manage open time for mixture control.

If you have a noid light, you could connect it to one of the injector leads and see if you are getting an injector signal.

you could also check to verify that you have 12V at the injector. the injectors should receive 12V form the 87 pinon the DME relay with the ignition in the run position. IF you test for 12V with only 1 injector disconnected you will actually show 12V on both pins of the plug as the injectors are wired in parallels and you will have voltage passing through the coils of the remaining connoted injectors to the DME controlled side, which is ungrounded when the engine is not running.

[mysocal911]

Originally Posted by 76FJ55

The injectors should be supplied a constant 12V from the DME relay. the ground path is controlled by the Motronic DME to manage open time for mixture control.

If you have a noid light, you could connect it to one of the injector leads and see if you are getting an injector signal.

you could also check to verify that you have 12V at the injector. the injectors should receive 12V form the 87 pinon the DME relay with the ignition in the run position. IF you test for 12V with only 1 injector disconnected you will actually show 12V on both pins of the plug as the injectors are wired in parallels and you will have voltage passing through the coils of the remaining connoted injectors to the DME controlled side, which is ungrounded when the engine is not running.

Post #21 provided the above info, did you miss it?

[mziggy16]

Originally Posted by 76FJ55

The injectors should be supplied a constant 12V from the DME relay. the ground path is controlled by the Motronic DME to manage open time for mixture control.

If you have a noid light, you could connect it to one of the injector leads and see if you are getting an injector signal.

you could also check to verify that you have 12V at the injector. the injectors should receive 12V form the 87 pinon the DME relay with the ignition in the run position. IF you test for 12V with only 1 injector disconnected you will actually show 12V on both pins of the plug as the injectors are wired in parallels and you will have voltage passing through the coils of the remaining connoted injectors to the DME controlled side, which is ungrounded when the engine is not running.

I don’t currently have a noid but may grab one tomorrow. However…

Injector plug #1 resistance tested within spec at 3ohm

But it DID NOT light the test light with the ignition switched to “on” or on the start crank.

I believe that fuel is getting to the rail from the pump (36psi) and the injectors are not getting power.

[mysocal911]

Originally Posted by mziggy16

I don’t currently have a noid but may grab one tomorrow. However…

Injector plug #1 resistance tested within spec at 3ohm

But it DID NOT light the test light with the ignition switched to “on” or on the start crank.

I believe that fuel is getting to the rail from the pump (36psi) and the injectors are not getting power.

All the injectors should have 12V with the key-on.

[mziggy16]

Problem Solved!

I was reading up on injector threads and came across this one, which referred to a six-prong connector near the firewall. I didn’t remember disconnecting or re-connecting this switch, so I went out to find it…unplugged.

I’ll have to double check, but I don’t recall the Bentley listing this one as a step.

This forum has been great. I’ve learned a ton through all the help here and troubleshooting some fairly easy, but seemingly complex, issues. Thank you.

Tomorrow…we drive.

[r_towle]

Ethanol sucks
Fuel filter replacement
Fuel pump pressure check valve replacement

Just did this
Car would crank for 5-10 minutes on and off
Finally started.

After 40 plus years, ethanol has ruined the fuel pressure check valve….cheap
Fuel filter was cheap,

You state it starts when you spray fuel cleaner into the intake.
Spark is not the issue.

[pmax]

Originally Posted by mziggy16

Problem Solved!

I was reading up on injector threads and came across this one, which referred to a six-prong connector near the firewall. I didn’t remember disconnecting or re-connecting this switch, so I went out to find it…unplugged.

Congrats.

I say there's a good chance the engine "unplugged" the connector for you during the drop.

That thread has some oscilloscope traces of the sensor and injector waveforms.

https://forums.pelicanparts.com/porsche-911-technical-forum/748619-injectors-not-spraying-4.html#post11792513 has som

[mziggy16]

Originally Posted by pmax

Congrats.

I say there's a good chance the engine "unplugged" the connector for you during the drop.

That thread has some oscilloscope traces of the sensor and injector waveforms.

https://forums.pelicanparts.com/porsche-911-technical-forum/748619-injectors-not-spraying-4.html#post11792513 has som

I think you’re right. Pretty well hidden on the triple check that all the plugs had a home.

Now I have to figure out why it’s running rough and the cat was red hot after a short drive tonight…