Welp, turns out my 'Cam Position Sensor' code was being caused by a Camshaft that wasn't spinning at all.

After a month of troubleshooting in my garage, I towed the car to a local shop where he found no compression on Cyl4. After removing the passenger side header, he saw the valves weren't moving when he turned the crank. Out comes the motor. Everyone I've talked to said that this is a *very* uncommon issue. My car was completely stock with only 33k miles on the clock... Before I bought it, I had a local dealer (in Indianapolis) do a PPI which showed everything checked out. The only item with mentioning was an over-rev to about 9k rpm about 4 years ago... Anywho, here we are today... problems in plain sight and needing to be resolved.

I'll update more in a little while (at work right now)... but I would love to get some supplemental input from a few of you regulars on here on what I should do while the motor is apart. My builder is making some very logical suggestions, and Tim from here on the board has been a huge help thus far - both before and after diagnosis.

So far, I'm hearing clutch (anyone run a Spec Stage 3+ ?) and (pre-turbo) hard inlet piping... and since the motor will be apart, rods (Carrillo) for sure... and perhaps: GT3 oil pump, GT3 Intermediate Shaft, and possibly some mild port work on the intake side of the heads (while they are getting their valve job...) Incidentally, should I go ahead and replace all of the valve guides in the head? I've heard they can wear prematurely and cause issues later on... I just want to do all 'common sense' stuff while the motor is out of the car.

Anything else I should be considering? If this whole thing gets TOO expensive, I might just say the hell with it and put it back together with 'original recipe' 996TT parts. I'm open to your suggestions and opinions.

Here are a few pics...

The culprit:

Timing chain sprocket on IMS: (You can see a chipped tooth on top of the right sprocket)


#4 exhaust valves are bent after smacking the piston: (Piston looks to be fine)


Something I *NEVER* imagined I'd be looking at only 3 months after buying my first Porsche:


More to follow...

 

Justin. Thanks a lot for posting and keep us inform of the rest of this build up. Don't forget to get the glued coolant pipes welded ! You can get the pipes on Ebay from this guy.http://cgi.ebay.com/ebaymotors/Porsc...s#ht_668wt_941 There is 6 pipes in the kit but I think there is a total of 7 that should be replaced. Good luck with your rebuild, J.P.

Forgot to mention. It is the first time that I see a broken timing chain on the TT....

 

In addition to the coolant pipes as mentioned above, I'd for sure do the GT3 IMS.

 

Good read is here. Same thing happened to some one on rennlist. Sucks man..
http://forums.rennlist.com/rennforum...nd-engine.html

 

This is why I asked if he had any mods...

 

I found two part numbers for the GT3 IMS:
959.105.91190
- and -
959.105.91112 (shaft with gearing)

Any idea which one I would need to look at? Price appears to be the same...

Part number for the GT3 Oil Pump is: 996.107.00794 ... yes?

And the Carrillo rods I would need are: PR-993>-65000S ... yes?

APR bolts and studs throughout?

 

Call Kevin at UMW to see what he recommends... I would think you need the IMS with the later part number.

 

That sucks. Sorry man. This is why over revs can be dangerous. Just too many possibilties and unknowns. On the positive side of things, fixing this will also allow you to go through everything.

 

That sucks!

One question, how do you know it was over-revved to 9k?

 

The car's life-long dealer told me about it after I paid for a PPI...

 

How nice of them! 9k would probably be the cause - that would def stress the chain...

 

I agree, 9k rpm is not good for any of those internals (I'm guessing it happened on an up-shift gone bad - or down) but it was also 4 years ago... I'm sure the car has been beat on plenty since then. Maybe it just tweaked it enough to guarantee a failure years down the road. ???

 

Also, my car is an X50 car... does this mean I already have the better oil pump with the 2nd stage in it?? I hear the only benefit to going with the GT3 oil pump is the 2nd stage - better for hard cornering and acceleration AND creates more vacuum in your crankcase. Thoughts?

 

X50 has the gt3 pump already. If yours is in good shape, I wouldn't buy a new one.

If you over-stress a mechanical component (beyond the loads it was designed for) even for only one time, you reduce its life significantly, because you reduce the number of fatigue cycles that it will last.
So that overrev to 9k has very hogh chances to be the cause of this failure IMO.


PS: Just a note about fatigue life FYI....Steel components can be designed to last an "infinite number of cycles". This is not the case with Titanium, Aluminum and other metals....therefore I wouldn't trust titanium conrods for example.
Weight aside, the good old steel is unbeatable strenght-wise.

 

Any metal debris in the oil pumps or filter?