Just bought a nice 2001 911 Carrera with reasonably low miles (85k). Getting a timing error code when trying to get it inspected and took to Rennsport in Sealy, TX (Warren is great). Appears that the timing is off, measure on laptop at 24 and should be at 7 or under (?). Has anyone else experienced this? Wondering if it was when the previous owner did the IMS fix....Understand that these engines are "5 chain" and it could be several different issues related to timing?

 

I'm assuming this is camshaft deviation, "spec" numbers are +/- 6.

24 would be way off. Per another forum member (Porschetech3) on a recent discussion about this, each link in the cam chain is about 12 degrees, so your PO probably did some work on the cams and got the timing wrong by 2 chain links.

Rennsport didn't give more info or advice?

 

That makes sense, thanks! Apologize but I'm a Porsche neophyte, have been in American muscle previously (happy to be learning about Porsche for the next years). Wouldn't the car run poorly with that type of a deviation? Assume the engine is at risk? I have an appointment to get it fixed this Monday.

 

It could also be that the variocam actuator has failed in the full advanced position..

The shop needs to test the varicam thoroughly for correct function, along with checking the static exhaust cam timing, and the exhaust to intake cam chain links/timing..

 

Porschetech3 has been helping me on the timing issue on my 3.4 Vario Cam system since the rebuild I did. It is important that you know whether the error in the Camshaft Position deviation (for either bank 1 or bank 2) or the Actual angle for camshaft bank 1 or bank 2. The former shows the position of the camshaft(s) relevant to the crankshaft the later shows the position of the camshafts as the RPM changes and the actuators advance the camshafts.

When you sent the cam timing with the Porsche tool (or aftermarket tool) you are setting the position of the camshaft to the crankshaft by aligning the slots on the exhaust cam(s) directly up and down while the crankshaft is at to top dead center (this is done independently on each bank which is critical as the crankshaft has to be rotated 360 degrees between setting each bank). However, the cam position sensors take their reading on the intake cam. The position of the intake and exhaust cams is controlled by the number of links on the chain between the two cams. So even if the cam is in the correct position to the crankshaft if the number of links on the chain between the two cams is off the ECU can measure the deviation as being off. And the intake cams are off relative to the crank.

So on my car the bank 1 deviation read as approx. -12 degree and the bank 2 reads as -22 degrees consistently. even though the exhaust cams may not be in "deviation." This would/could be because on bank 1 the cams are off by 1 link and on bank 2 off by two links. This means that the exhaust cams are fine but the intake cams and their functions are off the 12 and 22 degrees.

I am in the process of dropping the engine to view and correct this now. Some say you can do this with the engine in the car, but it is incredibly tight to take off the cam covers, take out the cams and actuators, reset them and then reinstall everything and get the cam covers resealed without any leaks. Having had the engine out of my car several times over the 23 years that I have had it I think it is easier to just drop the engine (and this is doing it in my driveway on jackstands. I have actually dropped the engine in 4-5 hours in the past but after so many winters many of the nuts and bolts which should only take a minute or two to take off can take 10-15-20 minutes which can double the time it takes to drop the engine. Fortunately putting them back in does not go so slow.

And now I am dealing with some vertigo from working on a roller creeper under the car and had to stop work last Sunday just as I was about to undo the transmission mount bolts and lower the engine. My head was spinning so badly I could barely sit up and the vertigo often lasts several days (until the crystals in your inner ear settle back into place). I went out in the garage this afternoon and laid on the roller creeper for a minute or so and my head started spinning again so I stopped. Very frustrated because if I could work for a day I could have the cams adjusted and the engine back in place.Hopefully a few more days and I can get back ait it.

 

Porschetech3 is correct here (again). On my Durometric log though you can see the actuators working as they should.

It is hard for me to believe that I miss counted the link this time around as I have done it several times before, but it is the only thing that seems to explain the readings on my engine.

 

You probably did count the chain links correctly and install the chain on the cams correct initially on the bench.

What usually happens is that when placing in the actuator between the cams in the chain and then handling the two cams with chain and actuator trying to get them into position in the heads, one of the gears will slip on the chain a tooth or two one way or another without you noticing...

Intuition would think this isn't possible but it happens all the time..so always verify/double check the cam to cam chain links after they are in place in the head before proceeding...

 

Taking the car in to Warren at Rennsport in Sealy, TX on Monday. Assuming the car isn't safe to drive, so the weekend will be lame!! Appreciate all the insight and comments. Learned alot!!