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Hello, I recently replaced my timing belt on my 2012 sport wagon tdi. I had cam and pump locked at tdc, crank locked and even marked the belt to the sprocket on each sprocket. Put same marks on new belt and everything went back how it was. I started it and ran/drove it twice and then all of a sudden it would start then doe about 3 times before finally starting. Once it started it seemed to run just fine. I had no engine light but scanned it and found p0016 code for timing correlation. Saw a different thread that had a similar problem. He said the mechanic found it was off by half a tooth, not sure how that’s possible, but if it is I’m not sure what to adjust, the cam pulley orrrr?
 

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Being a TDI mechanic for three years and changing countless timing belts the ECM must see a proper air to fuel ratio adjusted (with in timings dependant on the cams intake fuel compress and vent exhaust) via the cam sprockets set tooth distance on “REAL” TDC after the belt has been installed it cannot be out by more then 20-35% timing between detecting an A/F ratio from the o2 if it is out it’s because the o2 has picked up on either wet exhaust (rich), very dry exhaust (lean) there for must be reset on the camshaft TDC then loosen the lock nuts on the cam and then adjust the crankshaft to TDC so that the whole system is at TDC if your cam cannot be set back to TDC loosen the belt and re adjust a tooth forward or backward depending how lean or rich the mix was.
 

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How did you lock the hpfp, cam and crank? Could something have not been tightened down or tensioner not right and it skipped a tooth after first couple of starts? Are u scanning with vcds?
 
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