jdexter

http://www.autoatlanta.com/porsche-p..._911_parts.php

there is a copy of the service manual online someplace. if you can't find one, pm me I can send you a copy

pfbz

This thread has some good information on turbos, primarily wastegates and actuator rods... Skip ahead to post #24 for info on adjusting the actuator rods, which also illustrates how the system works.

wkf94025

I replaced the MAF sensor this evening, and failure mode / symptoms remain the same:

• ABS/PSM failures within a few blocks of startup
• Durametric reports:
  • engine fault code P0103 fault code 115 - Hot film MAF sensor
  • ABS/PSM 5.7 fault code 5525 - Incorrect data transfer with DME master control unit
• weak boost and same "sheet metal fibrillation sound" when boost would normally kick in.

Other ideas / theories / suspicions? (beyond bad MAF sensor)
Apparently I now have two good MAF sensors. ;-)
Tomorrow the search for boost leaks begins. Even if there is one, would that trigger ABS/PSM failure at low speed in low gears, modest RPMs?

geetee

sounds like you might have a major boost leak....do the boost leak test

wkf94025

Leak test starting tomorrow morning, at intercooler inlet, as described by @pfbz here in Aug 2018 post.

jdexter

make sure you physically inspect the turbos and wastegates while you are down there. You shouldn't have extra mechanical noises going on. Grab a video of the sound. See if you can move the wastegate arms manually. There is probably another guy with a tuned 996 around you. Maybe ask around to see if someone will come take a look. The car isn't that complicated mechanically once you get to know it. If its electrical, good luck.

johnsjmc

Despite the fact you have charged the battery. I have a similar car ,a 2003 manual 996tt with 50,000 mi.
When I bought it the car needed a boost to start as it had been sitting. During the test drive the psm,and abs warning lights came on. The dealer replaced the battery with a new one. There are no lights since and the car can sit a week without being started and start fine.
At the very least I would pull the battery and have it load tested . There was also a battery cable update tsb related to the warning light issues.
Simple fixes often solve seemingly complex problems on these cars.

wkf94025

A bit of a lightbulb went on this morning in looking at the DME manual. The pages on fault codes P0102 and P0103 both state that those faults will shut off PSM. So my ABS/PSM issues would seem to be a secondary consequence of MAF signalling boost is bad/unexpected.

Thanks all for your continued suggestions. Leak jihad starts now. Is there a separate protocol (or suggested thread) on vacuum leaks? @pfbz thread on boost leaks has been very helpful.

As to suggestion that battery still not sufficiently recharged, I doubt that theory for three reasons:

1. charger went green (good/done) after several hours on the battery last week
2. car cranks fine and has been started a dozen times and driven several hours since dead battery.
3. DME manual only calls for 8v on MAF testing. That's a long ways below ~12v.

The DME diagnostic pages talk about Porsche specialty tool 9637, which would seem to be a custom wiring harness that matches the pinout of the MAF sensor. A quick search online didn't uncover a convenient price or source of that tool. One ebay listing for $455. Anyone know anything about it?



Note text in red rectangle...

k9turbo

i suggested that very thing in the 3rd post of your thread. speaking from experience, i am pretty sure you are not self diagnosing this in the time honored way - given the maf would ( still is the first thing to eliminate as definitively causal - then the leak testing of course ) since that can/does cause *some* of the symptoms you've described. the accompanying and concurrent issues could well be a massive leak but as simple as a "hose".

i posted this near the top of your thread and it bears repeating ..

"and try running the car with the maf unplugged ( see how it runs then ) as the maf code is common and could on its own cause those "psm/abs" codes if the maf is "bad".

i think your problems are possibly only as vexing - as your not having had them before, as many of us have. many times lol

wkf94025

@k9turbo I have already run the car with MAF sensor disconnected, and the symptoms and fault codes were same/similar. I have cleaned the old MAF (see post #33), run MAF-less (see post #41), and replaced the MAF with new Bosch stock unit (see post #48). All tests failed to cure the problem. So now on to what @pfbz has been recommending for a while: boost leak testing.

I appreciate any/all suggestions from more experienced owners, and will research them to understand relevance to my current situation, but since new MAF made no difference, boost leak seems #1 suspect at the moment. And I'm convinced that having the boost leak test rig and knowledge is going to be helpful in the long run of my 996TT ownership.

My only point in posting the page from the DME diagnostics manual is to eliminate any doubt for others who might someday find this thread useful that the P0102 and P0103 MAF faults *will* disable the PSM, so don't go chasing the PSM/ABS failures until MAF faults cleared. Given that my indy replaced right front axle, I was wondering if something on the speed sensor for that wheel might be a problem. That theory now seems very unlikely.

The only thing that's vexing at the moment is shop near Chicago who did the work that I suspect introduced the problem. Not impressed by their responses thus far. They confirmed they didn't check for fault codes or push boost in the test drive after doing ~$4k worth of work. Topic for another day.

k9turbo

forgive me. i hadn't noticed that you had actually swapped out the maf etc. only that you later seemed to surmise that it could in fact be maf related coupled with the boost leak *probability*. it''s frustrating no doubt. wishing you luck, and ultimate resolution.

blazen244

+100 on this Euros do not operate well with low charge clear the codes and charge the battery and then go for a drive.

wkf94025

Initial success yesterday on my "bug hunt", though car is still jacked up and test plugs in place, so no road test yet. Thanks to guidance and documentation by @pfbz I DIY'd some PVC plugs with quick connect, and clamped them into the hoses that run between compressor output and intercooler input. First pressurization quickly revealed a loud sound of air escaping in the left rear corner of the engine bay, coincidentally in the vicinity where one as-yet-unnamed-indy did some work (motor mount, heat shield, plugs and coils) before car's shipment west. It took me several cycles over ~10 minutes of recharge compressor to 20psi, connect quick-connect, and run hands around in tight spaces to fine the source of the wind. Lo and behold the large black hose exiting the left side intercooler was completely off the intercooler fitting.




Anything look amiss here to you? We'll talk later about the shop that did this fine work.

Two other things en route to this finding that I'd love some advice on: 1) oil in the left side turbo; 2) hose "splice" on the right side turbo.

On the left side, I put a blank plug in first, before discovering the right side hose was more constrained in access for the quick connect hose, and decided to swap plugs (quick connect on left side, blank plug on right side). When I pulled the blank plug off the left side turbo, there was oil in the cup, from having been in place for maybe 15 minutes. Is that expected? See photo here of the cup post removal from left side:




Regarding the right side hose between compressor output and (I presume) intercooler input, there is a "splice" or "patch", wherein a short section of larger diameter hose is clamped around the original hose as it connects to compressor output. Is that stock, or did someone decide a cheap patch was better than replacing the entire hose. There is a metal sleeve inside the factory hose in the vicinity of this junction. Here is a photo of it before disassembly:




Here are left side and right side plugs installed. They remain in place this morning on the assumption that first big leak found isn't the last leak to be found, and once I solve the first leak found, I'll be in re-test cycles for a while. Note also how rusty the actuator is. Is there a test on their operating condition that doesn't involve engine running?


Left side plug, with quick connect to compressor 20psi hose


Right side plug, blank.

I welcome any advice on:

1. securely reconnecting the big hose in the left rear corner, coming out of the left side intercooler. Am I pulling bumper, airbox, both, other components?
2. oil in the left side turbo?
3. is the right side hose splice factory or someone's cheap fix?
4. how to test the [waste gate?] actuators while I'm down here?

First time in this arena, in case that wasn't obvious. Thanks for any guidance here.

EDIT: for those who guessed boost leak as the root cause of the fault codes, ABS/PSM lights, etc., you win, and we have a special set of steak knives we'll be shipping out to you as soon as road test confirms root cause. For those who predicted battery depletion as root cause, the battery went on the charger during boost leak jihad, so you can claim success as well because I'll be road-testing a fully recharged battery and major hose disconnect fix together. But sorry, no steak knives for you. And for those who predicted bad MAF, I'm actually thinking original MAF may still be good, and will be reinstalling it more just out of curiosity, and checking the signal voltage as logged by Durametric now that I know that a healthy MAF sensor logs voltage values in the 0 to 5 range. In any case, no steak knives for you. Though I don't mind having a spare MAF sensor in inventory.

deadendd9009

I'm really happy you found your problem, congratulations! I think this is a lesson of starting with the easy stuff and moving your way up. You now know your car better than a lot of people do.

As to your questions:

1. You need to remove the bumper and airbox only, I think you'll fiddle too much and it'll take longer not removing it...and I'm not sure it can be done without taking the rear appart. Its a 15 minutes thing. Word of advice, once the hose is clipped, there has to be NO gap (top or bottom) of the hose, it's a very tight fitting clamp. The shop that did your work did not follow this warning, and you see the result now.
2. Oil in the left side turbo is ok, just depends on the quantity. Have you had a recent oil change, and they would've overfilled?
3. This is factory, but those worm clamps need to be replaced from corrosion.
4. You need a vacuum pump. My advice is to fix the hose and drive it to make sure the codes are gone. You don't want to work on another component and create another problem. Fix one first and move your way up.

Cheers!

k9turbo

congratulations for finding the leaks and for your thorough DIY capabilities. i was always in the maf and/or leak "camp" so only half right. i'll accept your kind offer but feel i might only be deserving of a paring knife lol. good job.