New mustang pip sensor installed and waveform not clear

[Cris]

I installed a new pip sensor on my 95 mustang 5.0 and the wave pattern isn’t nice and squared. The pattern is jumping all over and Im thinking bad ground? Could this be a bad ground?

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[Andrew Phillips]

When I see a PIP waveform like that, I think bad crank position sensor (CKP). The image below is from a 95 mustang with a bad CKP. Notice how the PIP is similar to yours.

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• 50256e17c76bb17f0a60d783001c66cf

[Cris]

I notice when i disconnect the spout the wave form is much squared and better looking, but when i plug in the spout the wave form isn’t nice. Any ideas why would that be? What could be the problem?

[Andrew Phillips]

Without seeing the car and running tests in person I’m just hazarding “educated guesses” based on past experience. One other thing that I might mention, especially since this is a long-term and ongoing issue, is that the clipping on these waveforms could also be caused by spurious AC riding on the circuit. This can be caused from any component that generates AC, such as alternator ripple. Too much AC noise on the digital lines will definitely wreak havoc. You may want to have the alternator tested, specifically a diode pattern test, even if it is charging properly, as it may be leaking AC onto your DC circuit path.

For comparison, here are ‘good’ waveforms:

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• a27116f56982675e23c5fd82aa70e6a3

[Cris]

I did check for continuity on the power and spout wire and it is good. The alternator voltage is steady at 14.5. I will get it tested and see if it is bad.

[Cris]

I used the voltmeter to check the AC ripple. On the AC scale it shows 60 to 70 millavolts. I compared that to my daily driver and it only shows 20 millavolts. So the AC ripple on the alternator is bad.

[Cris]

I removed the alternator and the bearing was making noise when I spun it. I replaced the alternator and I checked the AC ripple and still over 50 millavolts. I don’t why that it? PCM issue not able to control it?

Here is a video showing the pip and signal changes when spout plugged in.

[Author]

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