D.I.Y. 996TT Redneck Engine Build Thread.
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I swapped the sensor and that didn't work. I actuated the variocam on the durametric and then the sensor started working. Go figure. Anyways, it works. My understanding is that the timing tolerance is + or - 6 degrees. On cam 1 I am showing +1.8 and on cam 2 I have -2.94. This is apparently well within spec but certainly not the perfection I was striving for. The measurements are at the crank so basically I missed by less than 1 degree on cam 1 and by slightly more on cam 2 at 1.4 degrees or so, which is very close and should not affect performance. I've been reading up that these readings are pretty much all over, even with the factory install because the variocam is pretty slopply. I'd like another try at it sometime but I will run it for now. On with the completion of the car.
Wouldn't that be almost 5 degrees out. One is 2 over and one is 3 under. Either way, congrats on getting it back running!
From what I gather the way that is measured is at the crank which spins twice per engine cycle so it doubles the number as shown at the cams, which spin once per engine cycle. Those kind of numbers are pretty normal. My adjusting also takes the lobe wear into account where the cam sensor does not, so my actual lobe opening and closing should be closer (I hope). I used a cheaper aftermarket sensor on the #2 bank. I'll switch it back to the Bosch sensor to see if that makes a difference.
Last edited by brnrdtns; Nov 20, 2019 at 09:33 AM.
The more I think about the timing thing the more I think that my timing settings are really good and the sensor system is a bit off. I put those cams right on the marks at the top of the dwell on each side of the variocam movement and checked them over and over. I think between the slop in the chain at different speeds, the chain tensioners with variable oil pressures, and tolerances in the cam cover (which holds the sensor), I believe that the timing reading system is not perfect. I think it was only meant to tell you if something is very wrong with your engine and not to give a perfect reading to the ECU. The variocam does only operate fully back and fully forward, nowhere in between as far as I know.
Anyways, I took the car for a spin and all seems well. I didn't full boost it up yet. I probably won't until the spring time but it is good to have the project finished.
Anyways, I took the car for a spin and all seems well. I didn't full boost it up yet. I probably won't until the spring time but it is good to have the project finished.
The build has been solid. I've got around 4,000 miles on it now. I've had plenty of issues to work out with my custom fuel pump, tune, and getting through emissions but the motor is trouble free.
Yah no problem. Several people have done the same. I am talking to someone who is currently building one, waiting for parts at the moment. You can click on my instagram and message me from there also so I will see it right away.
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