Continuity Test Results, Help to interpret Continuity Test Results Options

[MFejsa]

Need help to interpret results of continuity test results (see attached) and explain what to do next to get my car running right.

Porsche 914 2.0L 1974 (I believe was originally a 1.7L)

My car starts, runs and drives but idles rough and wont rev past 4,000rpm. It hesitates on acceleration. I have changed virtually all components / parts from rebuilt MPS, tested TPS and works, ignition switch, fuel pump, air & cylinder head temp sensor, swapped out ECU to one that was tested to work, and the list goes on.

I am posting my continuity test results with the hope that some may have experienced or had the same results and knows what to look into more deeply or can diagnose.

The test results concluded the following:

1. When testing the ECU power source from main power relay I could not get the 1V voltage difference from the voltage measured at the battery terminal. No difference and remained the same. Voltage at the battery was 12.79 throughout

2. when testing the voltage at start signal from ignition switch the voltage dropped to 9.7V and was not greater than 12V. However, should be greater than 12V.

So, can anyone help, please. I haven't been able to get the car run and drive right since being restored and have run out of options.

Regards

Michael

[Van B]

Wait, are we gonna talk about that 9.7v?
What was your voltage at the battery? If you’re getting 12v at the battery and only 9.7v between that pin and a ground, I recommend looking into that first. If you’re only getting 9.7v at the battery too, then you need to make sure you’re meeting required voltage. All kinds of weird gremlins can appear when insufficient voltage is in the circuit.

[MFejsa]

Im getting more that 12v at the battery but 9.7V at the pin and ground

[Van B]

Im getting more that 12v at the battery but 9.7V at the pin and ground

Search around and make sure you got a good ground when you measured at the pin. But that’s a huge voltage drop and needs to be looked into.

Let me elaborate further. On the Porsche 996, the hot cable to the starter is known to corrode inside the sheath. The behavior exhibited is exactly the same, won’t rev past 4K. Looks and feels like voltage regulator, and it can be. But generally on the 996 it’s either a regulator, crank position sensor, or the corroded cable. The cable is the one most often overlooked.

[MFejsa]

Hi, thanks for the message.

Check all grounds many times and made sure that they were all firmly crimped.

Also, swapped out to nee voltage regulator early today and still get the same reading at 18 pin.

Cable to the starter has also been replaced with a new one. When you say hot cable I assume you are referring to the cable from starter to battery?


Regards

Michael