Driving it off the cliff

[ike84]

Looking at that chart I can count 6 blue spikes where there should not be (albeit small ones) while there are no abberant red apikes. Does that indicate spark plug voltage when there shouldn't be? Like a short in the wiring?

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[blue62]

I have ZERO knowledge on reading Oscilloscope waveform so I do not even know what to look for.

[Stl-986]

I honestly dont know. Would need to do the same test with my 03 to know what it should look like on a good running car.

It does seem like it could all be a wiring issue or DME issue but, the DME tested good per ecu dr and it wiring wouldn't explain some of the other issues like the oil light coming on or hard downshifting, but of which can be caused by vacuum/pressure.

At this point I think I am going to just have it transported out to KC and have KC Rennsport have at it cause I am running out of ideas.

I could do another AOS but that damn lower accordion hose is just such a pain to get back on right.

If anyone has any other suggestions on what to try or parts to replace I am all for it. I dont mind throwing parts at the problem depending on what it is. Hell I would even replace the header with precat if I could find a used one somewhere.

[blue62]

Originally Posted by ike84

Looking at that chart I can count 6 blue spikes where there should not be (albeit small ones) while there are no abberant red apikes. Does that indicate spark plug voltage when there shouldn't be? Like a short in the wiring?

Sent from my SM-G970U1 using Tapatalk

I enlarged to about 300% I now see the small spikes on the blue line Channel A=Cyl 1
I know nothing about scope waveform, but Channel B be is not doing it.
But where he is hooked up shouldn't that be signal from the DME/ECU to the coil ?????
Not the plug firing????

[Stl-986]

according to the wiring diagram that is the coil wire from the dme. At the coil 1 wire goes to ground point 12 and another to 42.

I'm not all that good at wiring diagrams sometimes. What is that 42 circled in blue?

Anyone know exactly where GP 12 is in the engine compartment?

[Stl-986]

Coil wiring:


Ground points. Where exactly on the engine is GP 12 though? I know there is a couple ground wires right by the AOS at the corner of the intake manifold, but that isn't what is shown in the diagram. Diagram has it more in the center of the engine, but the throttle body.

[blue62]

I was looking at the Pico website.
There is information on using and testing with the Pico.
Also there is a waveform library that you can access.
Could be of some help.
Keep me in the loop on what you do with it and what you find.
After this long I am hooked...LOL

[blue62]

Originally Posted by Stl-986

according to the wiring diagram that is the coil wire from the dme. At the coil 1 wire goes to ground point 12 and another to 42.

I'm not all that good at wiring diagrams sometimes. What is that 42 circled in blue?

Anyone know exactly where GP 12 is in the engine compartment?

Automotive electrics is my weak point.
But if 12 is a ground point then my guess from looking at it is that 42 is a wiring harness connection with all positive leads.

[Stl-986]

The only thing at 12 is the main ground wire that goes over to the SAI pump. Been looking at wiring harnesses and it looks like the one I mentioned by the AOS & corner of the intake are the ground terminals for the coils and other things on bank 1. That is good & secured to the engine. So if it is a wiring issue it is going to be one of the other wires, a break (unlikely since it does fire) or a chafed wire.

[RedTele58]

Originally Posted by Stl-986

So if it is a wiring issue it is going to be one of the other wires, a break (unlikely since it does fire) or a chafed wire.

Remember this from page 2, 10 days ago? Have you looked for this?

"Sorry to be late to the party on this one, but I had an almost exact situation last month with my '02S. Same misfire codes on one bank.
I ended up taking mine to my Indy shop where they discovered a bad #4 ignition coil housing on the engine wiring harness. (which looks to me like the only thing you haven't replace)
They state they use to be able to get just the individual housings, but now Porsche wants to sell the entire engine harness. Fortunately for me, they are still able to source the individual units. (And yes, changing one connector housing cleared all the misfire codes)
You may want to check this out before you completely get lost down the rabbit hole."

You're pretty far down the rabbit hole. Not being smart, just trying to help.

[Stl-986]

No worries. it would be strange that all 3 connectors have issues. Would make sense if it was just 1 but all 3? When they did the work was it just the housing the replaced or did the splice in a new connector with wires?

[RedTele58]

Originally Posted by Stl-986

No worries. it would be strange that all 3 connectors have issues. Would make sense if it was just 1 but all 3? When they did the work was it just the housing the replaced or did the splice in a new connector with wires?

They replaced one housing. It cleared all the codes. Runs like a champ.

[blue62]

What is the coil housing we are talking about???

[Stl-986]

has to be just the plastic housing for the pins, only thing I can think of

[ike84]

Total disclaimer - I don't know **************** about a pico. But, if this tool is charting out voltage over time (which it appears to be) you have an issue with that the wiring somewhere between the dme and the spark plug.

Before you ship it out, I would repeat this test on your 03, or even on this car with cyl 2/5 or 3/6. My bet is that you won't see those spikes.

The spikes don't necessarily have to be voltage coming out of the ecu - there could be a break in the line that is allowing a short. Even a small insulation break - you know, **************** that tends to be exacerbated when things heat up (anyone who's has had a microswitxh issue knows what I'm talking about) - between that wire and another hot or ground could be causing the abberant voltage. Remember that the wire is just a conduit and your tool is reporting what it is detecting. Hell, there could be electrical short anywhere between the ecu and the spark plug tip. It's all conductive.

Here's what I would do - run the test on the different cylinders. If there are no abberant spikes, start working your way down the line from the ecu. First, cut the wire just after it comes out of the ecu (leave enough to splice back later) and run the test again. If the spikes are still there, it's an ecu issue. If the spikes aren't there, splice a new wire from there down to your coil pack and see what happens. If the spike returns the there's an issue with the coil pack wiring harness, coil pack, or plug. If there are no spikes then your car may be fixed and you owe me a beer. Or I just wasted a day of your time and I owe you a beer.

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[Stl-986]

Well, you can still owe me a beer, but I'll settle for doing a burbon run with you some time.

Pico is just an oscilloscope. But you do mention something that is worth thinking about. Instead of doing a pico scope I could just hook up my voltmeter.

Here is the question I have though. Coil has 3 wires going to it. ground, a voltage (not sure what voltage) and another wire. In coil ones case it is brown, black, green/black. Brown is obviously ground. But should the black wire have? voltage, ground, ?. What should the green/black wire have? The green/black wire is what comes from the dme. Dont know where the black wire really goes other then it's used by a lot of things. Injectors, all the coils, 02 sensors.

Who is our resident wiring diagram expert?

Not discounting this being a wiring issue. 2 common things with this issue for wiring. DME & bank 1 coils all use the same ground point. GP12.

[ike84]

Originally Posted by Stl-986

Well, you can still owe me a beer, but I'll settle for doing a burbon run with you some time.

Pico is just an oscilloscope. But you do mention something that is worth thinking about. Instead of doing a pico scope I could just hook up my voltmeter.

Here is the question I have though. Coil has 3 wires going to it. ground, a voltage (not sure what voltage) and another wire. In coil ones case it is brown, black, green/black. Brown is obviously ground. But should the black wire have? voltage, ground, ?. What should the green/black wire have? The green/black wire is what comes from the dme. Dont know where the black wire really goes other then it's used by a lot of things. Injectors, all the coils, 02 sensors.

Who is our resident wiring diagram expert?

Not discounting this being a wiring issue. 2 common things with this issue for wiring. DME & bank 1 coils all use the same ground point. GP12.

The black wire goes back to vs 42, which is a connection point for power supply. My best guess is that it is the source of constantly supplied power to the coils (and radio, interestingly) and that the signal from the dme opens the circuit to allow voltage from that supply to activate the coil. So, it should be 12v steady on the black, where as the dme signal wore should be an intermittent (probably 5v) signal.

Dude, I LOVE whisky. Burboun is great, I'm more into ryes as I've gotten older though. There have been few moments in my life where I truly believed in god, and those have been (in no particular order) the birth of my children, the 3 miracles that happened on my wedding day, and the first time I ever tasted Thomas h handy rye whiskey.

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[blue62]

With the "PICO" you should be able to test the entire circuit on a cylinder including DME and sparkplug spark. For function, shorts, resistance, what ever.
With a two channel you could compare Cylinder 1 to another cylinder or CPS signal.
Or the cam signal. Or any other electrical signal.

The "PICO" website has tutorials on running tests on various systems.
It has a good tutorial on Coil on ignition systems including the three wire coil.
It explains function of each of the three wires.
I read the info and from it I learned that the area you have circled in blue in post #126 is (VS 42) is a constant Voltage Supply point.
The tutorial also includes known good waveforms and how to read them.

You could also go to youtube and look for "Scanner Danner" he has many videos on using an Oscilloscope.

PICO is a great diagnostic tool I wish I had one.
But the caveat is: If one doesn't know how to use it then it is of no value

After attempting to help with your issue and following everything you have tried.
It looks like most of the problem is with cylinder 1.
Although I know zero about waveforms or "PICO" it does seem that the issue with cylinder 1 is electrical.

[Stl-986]

I'm still learning pico. It's a great tool and yea, if you dont know how to use it right it's like using a hammer to put in a screw.

Yup, does feel like electrical, cause electrical could cause every one of the issues I am having and/or cause the domino effect of what is happening

[blue62]

Originally Posted by Stl-986

I'm still learning pico. It's a great tool and yea, if you dont know how to use it right it's like using a hammer to put in a screw.

Yup, does feel like electrical, cause electrical could cause every one of the issues I am having and/or cause the domino effect of what is happening

Well keep me in the loop of what you do with it and the final outcome.
Always interested.
Sorry I wasn't able to help you resolve the issue.