The Camshaft Deviation Saga

The Camshaft Deviation Saga Greetings, folks. You may remember some months back I had a partial IMS failure (found flakes in the oil filter), and took the car to the independent shop I bought it from. They said they'd help me out. We put in a new LN Engineering bearing, did valve grinding and head porting, and everything looked decent. No real damage that needed attention. However, I was deep into this job labour wise, so we installed a Fabspeed Cold Air Intake system and the Fabspeed SportCat system so I felt like I got something for my many thousands of dollars. Check engine light stayed on, and my shop noted that this was because of the sport cats and that the O2 sensors weren't functioning. Fast forward a few months, and the car sits because I have exams. Valve lifter chatter is heard by my ex-technician grandfather, who tells me to take it to a Porsche speciality shop to have a second opinion. I ask to give the car a total once over, because I'm moving to the East Coast soon. Once over reveals an engine code showing camshaft deviation of 6 degrees and a vacuum leak (adding fuel of 4.5% at idle). Idle is a tad rough since initial repair, and tends to try and "search" at idle. Otherwise, car feels okay. Second opinion shops tells me to go back to Shop #1 to get the timing redone. Shop 1 offers to re-time engine and admits they were off because they didn't have the Porsche tools at the time, so they buy them and claim to time it properly. Vacuum leak is fixed (O-ring) and fuel stops being added. Timing STILL reads 6+ degrees of deviation. We end up doing the camshaft adjuster solenoids, as a few people mentioned they can go and throw the timing off. We re-time, do the solenoids, and pack it back up into the car and restart. Still the deviation. Tear is down again, however, they haven't been able to get rid of the deviation in Bank 1. The shop has taken the engine apart and re-timed it several times, and Bank 1 shows worse deviation than before it went in. Here's what we've done: -We've replaced some worn guides (improved Bank 2's deviation) -Replaced camshaft adjuster solenoids -Shop reports chains and tensioners are sound So, what's the likely differential diagnosis here? Should I just replace the tensioners and the sensors? Is this a computer glitch? The shop is looking to bring in an expert, and honestly wants to send it to Porsche. I never had any issues with any of this prior to the IMS repair. Who should pay? I've offered to pay for parts and they're taking on labour right now, but if it goes to Porsche themselves, then what? The fact that the car is running well is a great sign, but I'm shipping out with the Army and going to the middle of nowhere. I don't want a real deviation to cause longer term problems. For reference, car is a 2001 3.4L C2 with 110,000 miles. Thanks guys, I really appreciate any and all help! -Matt

What error codes are you getting? Mine was throwing P0011. Diagnosis showed about 11 degrees off for bank 1 across all rpms. Appears to be cam vane cell adjustor sticking. Two different high quality shops felt that is the likely cause, something they see every couple of years. It goes to the local shop tomorrow to drop the engine and replace this part. I'll post the results later this week.

You need to have the crank timing checked. The cam timing signal is measured relative to the crank timing signal. If that timing interval is too short or too long, a cam timing fault occurs. Use an o-scope to actually measure the two banks' timing differentials relative to the crank signal.

Error codes were: P1128 - O2 sensor adaptation bank 2 P1130 - O2 sensor adaptation bank 1 P1117 - oxygen heater circuit behind cat bank 1 P1118 - oxygen heater circuit behind bank 2 P1341 - Camshaft Deviation -Matt

If CEL, what codes? Cam deviation is fine if it's 0 degrees +/- 6 degrees. Usually the cam deviation moves towards negative as the cam pads wear. Do the noise go away after warm up? Can return to the stock airbox and see if that improves idling.

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You got these codes ever since the rebuild? From my memory, 1128 and 1130 is either too lean or too rich or MAF. The O2 sensor codes could be from bad sensors, O2 sensor fuse or just the sports cats. The 1341 I need to look it up again but it could be bank1 variocam actuation. Could be many possibilities. Would be good if you can put the stock airbox and cats back. They will help the diagnostic.

Here's the story behind my P1341 code: failed seal in the VarioCam actuator that was causing it to stick in the wrong position, unable to quickly snap from normal position to advanced position. https://rennlist.com/forums/996-foru...cam-p1341.html I had green rubber bits in the oil filter for a few thousand miles before the CEL came on, so it appears the seal was slowly tearing itself to bits and then eventually the remains of it came out of its groove and jammed things up.