Ian Claudi
Member
I own a 2003 Jetta TDI Wagon 5 spd manual with 125,000km. The car has been well maintained ( oil, filters, glow plugs etc ) and up until recently was completely problem free.
Note: The car starts easily ( even at -20c ) and I add fuel conditioner to each tank of fuel.
About 2 months ago, the car started suddenly losing power. This is most noticeable on the highway but can happen at any speed. It is now happenning several times a week. When it occurs, it feels like the car has 'magically' transformed from a TDI to a non-turbo diesel. When driving on the highway, it becomes very difficult to pass other cars. Climbing hills requires a downshift.
When the problem occurs:
I took the car to my local mechanic and despite using two different scan tools, he could not read the error codes from the ECU ( although reading other error codes was not a problem ).
My brother-in-law had a similar problem that was traced to a faulty Mass Air Flow Sensor. I changed the sensor on my car but the problem remains.
Two questions:
Where can one find out about the OBD-II wiring harness. Just in case that a wiring harness fault is making it impossible for the scan tool to read the ECU.
Has anyone experienced a similar 'loss of power' problem. If so do you have any suggestions or hints.
------------ Thanks for the responses to my original post ------------------
First - The mechanic, Richard Kirton of Euroservice in Dorion ( excellent mechanic, reasonable prices, helpful advice, endless patience ) used two different VW scan tools, neither of which could read the ECU error codes. Richard's fiirst suggestion was to check all the fuses, which was done. Unfortunately, all the fuses were OK.
Second - I've read some of the posts on 'limp' mode and performed some additional testing. The car can consistently be put into 'limp' mode by accelerating hard for approximately 20 seconds. By turning the engine off and on, 'limp' mode is cancelled and normal performance restored.
Third - The radio is VW stock.
Fourth - I'll check the VNT actuator and the air intake.
Note: The car starts easily ( even at -20c ) and I add fuel conditioner to each tank of fuel.
About 2 months ago, the car started suddenly losing power. This is most noticeable on the highway but can happen at any speed. It is now happenning several times a week. When it occurs, it feels like the car has 'magically' transformed from a TDI to a non-turbo diesel. When driving on the highway, it becomes very difficult to pass other cars. Climbing hills requires a downshift.
When the problem occurs:
- The sound of the engine does not change
- There is no black smoke coming from the exhaust
- The glow plug light does not come on
I took the car to my local mechanic and despite using two different scan tools, he could not read the error codes from the ECU ( although reading other error codes was not a problem ).
My brother-in-law had a similar problem that was traced to a faulty Mass Air Flow Sensor. I changed the sensor on my car but the problem remains.
Two questions:
Where can one find out about the OBD-II wiring harness. Just in case that a wiring harness fault is making it impossible for the scan tool to read the ECU.
Has anyone experienced a similar 'loss of power' problem. If so do you have any suggestions or hints.
------------ Thanks for the responses to my original post ------------------
First - The mechanic, Richard Kirton of Euroservice in Dorion ( excellent mechanic, reasonable prices, helpful advice, endless patience ) used two different VW scan tools, neither of which could read the ECU error codes. Richard's fiirst suggestion was to check all the fuses, which was done. Unfortunately, all the fuses were OK.
Second - I've read some of the posts on 'limp' mode and performed some additional testing. The car can consistently be put into 'limp' mode by accelerating hard for approximately 20 seconds. By turning the engine off and on, 'limp' mode is cancelled and normal performance restored.
Third - The radio is VW stock.
Fourth - I'll check the VNT actuator and the air intake.
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