Sounds like you got some great people at the dealership. This story gives me hope. It actually sounds like how I troubleshoot and how I treat people (most of the time). LOL

 

Sorry if I missed this, but did they check the resistance of each injector and coil? Or measure draw when activated?

I had a situation where internal shorting was causing the DME to appear to not activate or appear to be a failed ground because the DME has transistors that simulate on/off with the transistors. Yet manual activation on the shorted part still showed that part was working. Do the injectors work like that? Could an injector somewhere else cause another injector not to work? Are there any shared connections among the injectors (like shared grounds)?

 

My car gave a little puff of smoke at start up a few months before my AOS failed FWIW. Daily driver!
Good luck.

 

Did you share Ashai's hypothesis with them ?I don't know the diagnostic capabilities they have with the pinout box but it could be something that they look for .

 

Resistance and draw of all six injectors were checked, along with the continuity of the wiring to the "problem" injectors #1 and #5 (including doing a complete bypass of the harness for at least #5 injector and I think #1 as well). We also hooked up an oscilloscope directly to the DME and observed no output signal being generated (it wasn't being lost in the wires and wasn't a case of a failed injector not responding to a signal). The injectors do share a ground, but our bypass testing included bypassing that and grounding the problem injector directly.

More importantly, when ECU A (the one with cylinder #5 problems) is installed cylinder #1 runs flawlessly at all loads and when ECUs B/C/D are installed (which have cylinder #1 problems) are installed cylinder #5 runs flawlessly at all loads.

If it helps, especially for anyone joining the thread who hasn't had a chance to read it through yet, here's a copy of the document I gave the dealer providing a brief history of what we've done/learned thus far:

 

My understanding is that the puff is only occurring at start when the car has been sitting for a few days+. AOS is the top priority after the misfire fix and it'll definitely happen before I daily drive it. Definitely has me a little nervous to put it off even that long but it's also tough to justify doing that sort of work when the car is in the condition it's in (not really driveable and no guarantee they'll be able to find the problem).

 

Good question. I haven't, so thanks for reminding me of that post! I'll have to pass it along to them. Hopefully it's something they'd be able to see in the pinout data.

 

I'm glad your indy and the Porsche dealership are being nice to you . They sympathize with you and know this unusual problem is not your fault. It also shows good on your character also, most won't be so nice with someone who is a jerk.

I really don't blame the dealership for going back over some of the same things your Indy has already done, I would have too.

Just a thought that could explain why DME A shows a fault on injector 5 while the others show a fault on injector 1. There is a good possibility that the software is different between DME A and the others. The software version can be displayed in PIWIS and should be checked by the dealership just for information sake. All the software versions will be legal for EPA in all states in the US, but there can be a lot of differences to correct or improve some functions/strategies/calibrations. DME A could have an older software version.

I hope you get this issue corrected soon, I am very interested in what the solution is. As far as any suggestions or idea's, all I can say is like I have already said before, I would do a visual inspection on the flywheel teeth before I went on to more "out-of-the-box" theory's..

 

Possible good news?

Just got a call from J (the service manager). He said they are now highly confident that it’s a wiring issue. H has gone over the mechanicals of the car in great detail (even correcting the slightly-off installation of the coil spacers from when they were replaced) without finding anything. Then, when they finally hooked the car up to the pin-out box, it stopped misfiring altogether!

Apparently, I was mistaken about how the pin-out box works. I was under the impression it sandwiched between the connectors of the ECU and the connectors from the harness, but from what J said it sounds more like “the anaconda” as they call it outright bypasses the entire harness at once (@Porschetech3, maybe you can clarify this?)! Therefore, if the misfire stops when the harness is bypassed, it’s all down to a matter of finding the bad wire. H is now methodically testing every wire in the harness and they’re hopeful that he’ll be able to find the bad one yet this week. It still wouldn't explain exactly why the misfire moves between cylinders when the computer is replaced, but if the bad wire is on the input side it'd fit my theory of bad input data confusing the ECUs and each one responding to the glitch differently.

J also asked me to agree to a higher-than-planned diagnostic fee after all, $1500 instead of the original $500 (10 hours vs 3.5), because H has now spent around 40 hours working on the car. I agreed because it’s not an unreasonable thing to ask and IF we’re right that it’s a bad wire the “fix” itself shouldn’t be expensive at all (they do deserve to get paid after all!).

If/when the bad wire is identified I’m going to ask them to test run the car with one of the more misfire-prone computers (C or D) as a way of double checking that we’re finally sorted before they put the interior back together. I think the original computer (ECU A) is the best of the lot, so that’s what I’m planning on having in the car long term.

And then maybe retitle the thread “The $10,000 Wire”? We’ll see, I’m trying not to get my hopes up too much.

 

Fingers crossed, brother, this one has been a nail biter. And I was serious about the beers

 

The "pin-out" box does not by-pass any of the original wiring harness, it adds more harness to it, with the provisional box to facilitate tapping into all inputs and outputs for diagnosis.

Installing the pin-out box should not correct anything unless it is a connection problem. But with as much disconnecting and reconnecting as this car had had with all the DME swaps, a connection problem should have already surfaced by either getting better or worse.

I don't want to rain on your parade, but I'm very skeptical at this point. I'm very surprised he has spent 40 hours at this point and is just now hooking up the pin-out box. I hope that at least within that 40 hours he at least verified the physical condition of the flywheel teeth..

I'm rooting for you...

 

As always your honest input is appreciated and I don't think your skepticism is ill-founded! Aside from the wiring being very high on my suspect list for a long time (confirmation bias, anyone?), the only element that is making me hopeful about this report was the news that the misfire went away while the pin-out box was connected. That wouldn't happen if it was the flywheel unless they simply didn't test it properly while the box was connected. I'll need to ask them specifically about the flywheel when we talk (even if it proves to be a wire I'm hoping to get a much more thorough understanding of what they looked at/tried for general knowledge about the condition of my car).

I'm honestly more confused than ever at exactly how the pin-out box connects, but from the way J described it it sounded like it augments the harness somehow (he even used the word "bypass," although I don't recall exactly how he phrased it). Maybe if there's a bad wire the "more harness" wiring of the pin-out provided a clear signal path around the problem spot?

 

The only thing I can think of that would make any since (besides a connection issue) is that there was an RF ( radio frequency) which is always produced by wave forms or coil osolations, that had gotten magnified by the oil saturated wiring inside the harness, and is disturbing/confusing/contaminating the signals to the DME. And lengthening the harness with good/grounded/insulated length of harness could have reduced the RF interference.

I know this sounds really out in left field, even "outer limits" zone, but the most difficult problems I have ever dealt with were caused by RF interference. But I rarely mention that because they are so rare, that people think your a quack for thinking of it..

Also they need to check the software versions of your DME's. It would be great to know if DME A has a different software from the others.Could explain some things.

 

You're not wrong: that's so bonkers it does sound like a quack theory! My head has been hurting just from trying to process through it! But, at the same time.... we're definitely going to be in that sort of territory if the harness testing doesn't pan out! I'm going to wait and see what they say in a few days since I don't want to pester them, but is it a correct understanding that if you're right the only solution would be a whole new harness?

 

Well, IF RF interference from oil saturated wiring is causing the problem, the best and proper repair would be to replace the harness.

I would suppose you can try to by-pass the wiring (like you did with the injector wiring) for the CPS , or cam position wiring, if you knew for sure which wiring the interference was coming into the DME on. But RF electromagnet interference is almost impossible to detect, an oscilloscope a lot of times won't detect it because it is in a part of the RF spectrum the the scope doesn't see. A Spectrum Analyzer would be more useful at detecting RF electromagnetic interference.

Modern automobiles produce lots of RF electromagnetic interference, all electric/electronic devices do. Every injector, coil, solenoid, relay, ect produce RF EMI and can combine to produce waveforms very similar to the CPS waveform., but good designs have filters in place to filter out the EMI noise , but if the EMI noise is magnified or amplified, it can be more than the filter can handle and gets through.

Like I said, this is "outer limits zone" and should be a saved for after "all else fails" before going down this road..