wkf94025

My new-to-me 996TT arrived yesterday, after shipment across the country, and let's just say we have a little research, learning, and fixing ahead of us. ;-)
I took it out for a road test, and though it drove well around town, experienced the following when I hit the highway and opened it up a bit:

• The engine gave off an interesting sound which occurs only when mashing the pedal hard. I don’t remember hearing this sound when I accelerated the vehicle the day of purchase when I first drove it at the end of Feb, and did a PPI (including road test) with a local indy. Granted neither the mechanic nor I drove it that fast on open roads that day. The sound is like either sheet metal fibrillating, or possibly (guessing here) a waste gate dumping? It made me wonder if the heat shield(s) diagnosed as loose during the PPI, and repaired by PPI indy prior to shipment, were still loose.
• The max boost I could produce on the highway at speeds (as displayed on the dash readout) while driving in the 60-110 mph range was 0.4 (rarely) or 0.3 (most of the time) when I felt safe pushing the throttle hard for several seconds.
• Coming off the highway decelerating somewhat hard from 110mph down to maybe 70mph I got a couple beeps and the alternating “PSM / ABS failure”, “drive to shop” messages flashing on the dash.
• A mile or so later, I got a separate CEL and “drive to shop” msg.

The car is 2001, all stock, and generally the PPI was clean. I put my Durametric on it, and cruised through all the screens, looking for fault codes, and key engine metrics. I found the following throughout the system:

• Engine:
  • P0103 / Porsche fault code 115 – Hot film MAF sensor
  • P1671 / Porsche fault code 407 – DME relay Porsche fault code
  • P1601 / Porsche fault code 660 – CAN timeout – instrument cluster
  • P1249 / Porsche fault code 231 – Boost pressure deviation Below limit
  • P1101 / Porsche fault code 594 – Input variables charge measurement
• Air Bag: Fault code 3 – supply voltage
• Litronic Headlights HBA:
  • Fault code 1 – Engine path left
  • Fault code 2 – Engine path right
  • Fault code 3 – Axle-position sensor front
• ABS/PSM 5.7: Fault Code 5525 – Incorrect data transfer with DME master control unit.

Good news is cam deviations were quite low, and misfires zero.

The shipper mentioned the battery died during shipment (after-market radio left on was his first theory). He had to jump the battery when it came time to shuffle the load on his rig. Could any of the above codes be triggered by a battery drain event? I'm not averse to clearing codes and test driving further to see if they return, but didn't want to destroy any clues too soon by clearing codes.

A couple other minor clues or facts to share in context of the above:

• Seller kept the car on a battery tender, perhaps indicative of the after-market radio (installed at car purchase in 2001) being wired (per shipper's theory) in such a way that it isn't ignition-switched in its power supply?
• During PPI there was evidence of rodents (seeds, etc.) in the area in front of the dash, driver's side, as seen through the plastic grill with frunk open. I am wondering if "P1601 CAN timeout - Instrument cluster" might be related to any rodent damage to wiring. All systems seem to function normally in the cockpit.
• During PPI the front right headlight wasn't working (witnessed by the mechanic and by me). A few weeks later, when I had same shop do some work on the car while waiting for shipment, the other mechanic said both headlights were working, nothing to repair. Interesting. What can cause a headlight to be intermittent in operation?
• Front right outer CV boot was torn, and some early sign of corrosion on the axle, so I agreed to have shop replace it. Could "Litronic fault code 3 Axle-position sensor front" be related to that?
• Other work performed by local indy prior to shipment included new spark plugs and coils, oil and filter change, right motor mount replacement (PO's shop had replaced left mount only), new drive belt, rear brakes (rotors, pads, sensors) and brake fluid flush.

Full detail on the car is here on BaT, if anything there is helpful. I can also post a bunch of Durametric screen grabs, or log a session if that is helpful.

I appreciate any advice from the experts here. I researched a number of these fault codes on rennlist last night, as well as phrases "PSM/ABS" "weak boost", etc. and understand the PSM/ABS failures can be triggered by a number of root causes. I'm also interested in learning more about DIY methods for reasonably competent owners diagnosing boost system issues (loose hoses, failed or oily MAFS, etc.). Yes, search is our friend. But so are the black belts here. Thanks in advance.



PS: it has the dreaded sunroof rattle, but that's a topic for another day. Plenty of threads out there already on that matter.

Carlo_Carrera

Yes, a dead battery can cause all sorts of codes to be thrown. Fully charge the battery, clear all codes and then reassess.

k9turbo

..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".

the car reads as if in "limp mode ( no boost past .4 ) " but the codes lead all over the map. no pun intended. and to carlo's point. simply having the battery die can cause all manner of weirdness. hopefully that's the cause of "most" of it. GL w it.

F.A.

Boost leak test too once you address those codes if you still can't boost past .4 bar and you don't have other codes you have a leak. Seems like you have your work cut out for you but I promise when it's 100% you will have no regrets on the purchase. Good luck.

Edit: I see you mentioned the Indy did the ppi but didn't drive it fast? So many problems manafest at wot you have to punch it at least once, that goes for all cars I test drive, not I'm an abusive way but you have to wind it up once or twice.

wkf94025

Thanks all for your rapid replies. Good to know that dead battery can wreak havoc. Today's game plan is set. And for the record, no regrets whatsoever, even with all these codes popping. :-)

jdexter

I know it was mentioned above, but we all will agree on the importance of a proper pressure test. Go buy the stuff and do it yourself. So many of these cars have significant pressure leaks. Its almost not worth tracking anything else down until you do that and unplug the MAF.

Road King

Congrats on the car. I'm also in the Bay Area, and can help recommend a competent local shop should you wish to outsource some of the work.

wkf94025

Is there a good shopping list and how-to posted elsewhere in this form? Numerous posts about doing a pressure test (and not a smoke test), but have yet to find any clear details on equipment and methodology for the pressure test.

jdexter

Markski sells a kit https://www.markskituning.com/produc...t-leak-tester/. You can make one DIY. Just google "996tt boost test" tons of hits, tons of videos.

KC-CarGuy

Congrats on the car and welcome to the club!

Mike Roblin

All parts from a hardware store. Take the airbox off and cinch the clamp over the end of the pressure tester. Works like a charm.

Pro tip: roughen up the end of the pvc with some sandpaper so it doesn’t slip out under pressure

T Kono

Also - temporarily add additional clamping force to the other worm clamp so the bellows won't blow off the manifold while under pressure. Learned that one the hard way.

wkf94025

Very helpful gents. Gotta run to some family time, but will: 1) recharge battery; 2) clear all codes; 3) road test, including stop at HW store for DIY pressure test components. Appreciate it!

Dock

My Turbo has the stock stereo, and to prevent battery drain I keep the car on a battery tender whenever it's parked in my garage.

wkf94025

Do you believe (or know) that stock stereo is a known drain when parked for extended period?