MAF sensor wiring splice, how to eliminate it as fault?

Originally posted in the 'what did you do ..' thread , this is a new thread so as not to jack that one up. @viper1000 @996-CAB @wyovino @sublm8 @2mAn and @FunWithPaul thanks for the encouragement and advice. I'm now getting just a P0102 fault code, others may come back, but right now this is it. Most recent fault code This seems pretty accurate, as the power trigger for the valved exhaust system is spliced off the MAF. My Indy did this for me, and it's worked flawlessly but I think I've got a broken wire under the sheathing, or the solder is causing an issue now with time, maybe corrosion? Here's a photo of the splice: The red wire with the fuse is the power for the exhaust valve. It looks like it was done correctly, with solder and heat shrink, but maybe I should be looking at another source for switched power for the aftermarket exhaust. I think I would use the switched power in the rear fuse box and run new wire. I don't see anywhere in the engine compartment? I've been doing some reading and it sounds like the MAF is sensitive to even tiny fluctuations in voltage. That even changes to the length of wire can cause issues? How do I use my multimeter to test the wires? Is there a way to prove the solder is causing the fault? Or is it better to assume a problem and try to fix it? I don't think I can buy a replacement harness for the MAF only. I would have to remove and replace the entire engine compartment loom? Ballenger Motorsport claims to sell replacement wire and clips for the MAF, in 12, 24 and 36 inch lengths. But I've had a look at the loom, it looks like it's all in one bundle through the firewall to the fuse box in the back seat. I've not looked at the interior end yet, so maybe the new harness in the right length would work. When it cools off I'll jump in the backseat and do as you suggested @FunWithPaul but It's super humid and warm here, and I didn't want to drip sweat all over my interior and the wiring connections in the back seat. I'll try to rig a fan but I'm hoping the humidity goes away in the next few days. Maybe I shouldn't try to fix this myself? Should I look for an auto electric specialist? I live very rural, and I've already had that disaster with PSC Halifax. There's a well regarded Indy in Bedford, but they are slammed and I'm having a hard time getting a response to emails. Thanks all, this forum and it's members are a great help. Some day I hope to actually drive my car again. Summers are short here. ​​​​​​ Grrr. I need to drive her.

Get rid of the soldered splice connection and put a proper open barrel splice in. See if it works. Even if it doesn't, at least that soldered connection will be removed.

First thing, get the exhaust power supply off the MAF. Whoever did that absolutely does not understand how sensitive that circuit is and it most likely is overloading it. As mentioned above, use a crimp vs. a solder joint and see what happens.

Quotes source post: 19581018

@zbomb thanks! Is this a good guide on how to splice? You Tube . What gauge is the OEM wire?

Quotes source post: 19581022

@Paul Waterloo thanks very much for the tips. It's weird, my Indy, who did a lot of the restoration on my car, did it. Maybe he had a bad day. I thought he was the bomb, but looking at the way he did the wiring, I'm disappointed. And he actually used double sided tape to afix the little controller box to the body. The tape must have failed ages ago, so the box was flopping around behind the tail light for who knows how long. What's worse, when I had the car flat bedded to Porsche Halifax they removed my airbox and inspected, saw the wiring, and decided that my car was 'modified' and they didn't want to work on it. So their tech buttoned it back up, left the mess, and didn't tell me about it. What a bunch of amateur hacks. Never again.

Quotes source post: 19581361

The good news is, it's an easy fix. Probably a few hours to swap power supplies and do the simple repairs. Best of luck.

If you must tap power in the engine compartment tap the oxygen sensor heater circuit. It is a high power circuit and doesn't care about voltage fluctuations.

Ignore all of these people urging you to replace a solder connection with a crimp connection OF ANY KIND. A properly soldered connection is far and away the best electrical connection you can make. Done properly it is the best physical connection as well. About 50 bucks in tools and a couple of youtube sessions is all it takes to become proficient. EDIT: but yeah, find another +12V source.

Quotes source post: 19581470

This absolutely NOT true coming from someone who builds hi-rel electronics for a living. There will be no, zero, none solder splice wire connection in any high reliability product that is not potted to be completely isolated.

I think you are barking up the wrong tree here That power circuit powers up not only the MAF, but on the 996.1 it powers just about all sensors on the engine including the vario-cam solenoids, injectors, both cam sensors, TPS, ISC, ect... It is a very popular circuit and I see no issue with adding one more low current item to the many that are already feeding off that circuit ...So I wouldn't blame the Porsche Center for deciding to use this circuit, that is just finger pointing.. Just disconnect the exhaust valve circuit until you find the intermittent short... It's true that the MAF is very sensitive to voltage issues and anything on that circuit that drops the power voltage down below 12v will show up as a MAF problem, but it is just the MAF sensor doing MAF sensor things... MY gut feeling ( experience) is that most likely one of the vario-cam solenoids is intermittently having a resistance of less than the specified 13 OHMS at certain temps....this is dropping the 12v power to less than 12v and showing up on the MAF as low input ... My advice would be to run a temporary power feed to the vario-cam solenoids to isolate them from the main circuit and also if they are the problem it will keep the engine from shutting down/going into limp mode... Then once the issue is confirmed/isolated you can schedule/perform the vario-cam solenoid replacement and revert the wiring back to factory... Of course this is just a long drawn out hypothesis based on decades of experience, that could be totally wrong, it could really simply be the exhaust valve relay shorting,( just simply disconnect the installed fuse to verify ) but I highly doubt it ...

Quotes source post: 19581757

No PT3, you've got more than a hunch. Its your vast experience with Porsche and this exact platform that gives you insight not many other non Porsche techs could hope to have. Many would be chasing their tail for a long time with this problem..... Anyhow, nice explanation of whats going on, thanks for sharing... As you say, checking the exh valve is easy to eliminate maybe first..? then move on to the problem. Would you fuse the temp power to the solenoids with a 5 amp fuse.?

Yes I would fuse the temporary power to the vario-cam solenoids.... 13 ohms @ 13v is exactly 1 amp per solenoid......I would build quick temporary power feed to each solenoid using two 1 amp mini fuses .... The fuses will protect the DME from burning out the internal transistor ...which ever fuse blows will be the offending solenoid ( they are $500 each ) A shorted vario-cam solenoid is always the cause of the DME transistor failure...

Quotes source post: 19581470

Controversy, I love it 😁. I snipped the 1.5 inch or so of the splice out. It's unfortunate that there's no slack at all at either end. It looks like I'll have to splice a new short length in, which means 2x splices. Ugh. Hope this works. I'm going to use copper butts. I don't see any way around it, short of treating the whole loom out and replacing it. So much fun. Ultimately I will do that, over the winter. Right now I just want to get her running. There's a PCA Cape Breton drive coming up. I didn't register for it, because car. 🤕. So I'll have to get creative on my own to make up for it. Maybe a trip to Chester to do a day sail. Or whale watching from Brier Island. That's a nice drive with a ferry trip.

Quotes source post: 19582029

Thank you @Porschetech3 for the valuable advice. I should not have snipped the solder splice out, the 1 amp mini fuse is right there on the valved exhaust power leaf. This is why I should never be allowed near an engine....dammit. what's done is done. I'll have to find a garage to do the work. Definitely not the PSC. The guys in Bedford have gone quiet, they're so busy. Would a competent VW tech be able to work on my car? I think there's one closer to me.

I used a simple butted connector and rewired the MAF today, and went for a drive with the valved exhaust relay disconnected. I had no issues, but I'm not going to assume the issue is resolved. I'll keep driving. My engine has 100k miles so I'll try to fund the top end refresh this fall. Solenoids and pads anyway.

@Porschetech3 maybe I just got lucky? I've put about 500km on it since I removed the valved exhaust relay from the MAF sensor wiring, and so far, no cels. Maybe new oil did the trick, who knows. I'm just going to keep driving her with a lucky horseshoe in the frunk. I did check with a good Indy and they can replace the solenoids and the accessible pads for me, it just costs 3k Canadian. I really need a working durametric so I can get cam timing deviations. I've asked Durametric to provide me with a new cable. Is there another product that can get that data? I don't want to pay to get the work done if it's not needed obv. Thanks