I have had a problem with my 2006 Jetta TDI for some time now, it is only present when the weather is above ~60 degrees. When the car is heated up I can get the car to hesitate in two situations. When I start from a stop sign the car will accelerate and then fall on its face twice in quick succession producing a puff of black smoke and then taking off like a missile. The second situation is while driving at steady speeds and part load; this produces a shudder which in certain situations can be maintained the whole way down the street. The car also has a Kerma tune installed. I have tried the following to solve the hesitation problem:
- Replaced MAF
- Pressure tested intake system south of MAF when the car was hot and was hesitating---no obvious leak
- Replaced vacuum tubing cleaned MAP sensor
- Cleaned all intake piping except intake manifold. There was ~.25” of buildup on the intake piping walls
- Cleaned EGR valve
- I had a separate tune created which turns off the EGR altogether. However, I still prefer to drive the car with the EGR engaged as the car is more drivable and seems to be more powerful. When the EGR is turned off the turbo tends to ‘hunt’ under steady conditions. For example when driving along at a constant speed the turbo will climb in RPM and then release causing car to lurch forward and then the turbo will climb again a short time later.
- Fuel filter has been replace several times
- N75 valve appears to be actuating the turbo vanes correctly (used VCDS to verify)
Over the weekend I replaced the EGR cooler due to signs of leakage around the by-pass valve. This seems to have just aggrivated the situation as the shuddering and hesitation has gone from being a hit or miss situation to something which happens upon acceleration from every stop.
- Replaced MAF
- Pressure tested intake system south of MAF when the car was hot and was hesitating---no obvious leak
- Replaced vacuum tubing cleaned MAP sensor
- Cleaned all intake piping except intake manifold. There was ~.25” of buildup on the intake piping walls
- Cleaned EGR valve
- I had a separate tune created which turns off the EGR altogether. However, I still prefer to drive the car with the EGR engaged as the car is more drivable and seems to be more powerful. When the EGR is turned off the turbo tends to ‘hunt’ under steady conditions. For example when driving along at a constant speed the turbo will climb in RPM and then release causing car to lurch forward and then the turbo will climb again a short time later.
- Fuel filter has been replace several times
- N75 valve appears to be actuating the turbo vanes correctly (used VCDS to verify)
Over the weekend I replaced the EGR cooler due to signs of leakage around the by-pass valve. This seems to have just aggrivated the situation as the shuddering and hesitation has gone from being a hit or miss situation to something which happens upon acceleration from every stop.