NEsportswagen

Started with poor low end throttle response and occasional stall and hard start. Pulled codes for g28 circuit no communication, intake cam shaft timing over advanced, and negative charge air deviation. Then a few weeks after symptoms started finally refuses to start or will start with bad misfires for about 10 sec and stall. Mileage is 124k. Have replaced engine speed sensor, cst valve, cs position sensor, and checked timing on both belt and cam shaft chain. Timimg was/is ok. Checked all fuses ok. Have swapped all coil packs. No improvement. Only mods are a KO4 w/o programming, k&n filter, apr exhaust. PVC valve and suction pump replaced, all coil packs replaced around 75k, and some vacuum hose have been replaced. Timing belt at 97k with the new turbo and thermostat. Plan to check compression soon.

BISHILVR

Sounds like a fuel pressure problem, also is your fuel filter clean?

NEsportswagen

The new G28 sensor must be the wrong range for the car. My code reader gave me a "range /performance" error for the new sensor. I put the old one back in and it started right up and ran much smoother than before. Will try to track down which G28 p/n it should have and replace the original. My best guess is it was the CST valve or solenoid that caused the original codes.

I did buy a new fuel filter but that's down the car to do list quite a ways.

For the record the CST valve replacement was done with removing intake shaft only, and exhaust cap 1 for clearance, and was not difficult.