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This may be of interest to some of you guys, to get some insight as to what's actually happening when a DV goes bad and exactly what this does to your boost.
This example is taken from an Audi A3 2.0 TDI 8P3 (stock map) we had in today displaying a classic under-boost fault.
When a car comes to us displaying these symptoms one of the first things we do is carry out a road test while monitoring a few key values. You can see in the attached image (Fig.1.) that the engine ECM is wanting to see ~2.4 bar peak boost (green channel) and the actual, achieved boost is ~2.0 bar (red channel), confirming under-boost condition...resulting in poor performance etc, etc.
After checking the DV function, we confirmed another DV faulty (as many of you will know, the diaphragm that fights the applied controlled vacuum to regulate boost had a leak, preventing your car from boosting to specification).
After fitting a new DV you can see from the values obtained during the road test following repair (Fig.2) that the actual boost (red channel) pretty much traces the desired boost (green channel), recapturing the our 400 mbar of lost boost and getting our performance back!
FYI:
Hope this was helpful
This example is taken from an Audi A3 2.0 TDI 8P3 (stock map) we had in today displaying a classic under-boost fault.
When a car comes to us displaying these symptoms one of the first things we do is carry out a road test while monitoring a few key values. You can see in the attached image (Fig.1.) that the engine ECM is wanting to see ~2.4 bar peak boost (green channel) and the actual, achieved boost is ~2.0 bar (red channel), confirming under-boost condition...resulting in poor performance etc, etc.
After checking the DV function, we confirmed another DV faulty (as many of you will know, the diaphragm that fights the applied controlled vacuum to regulate boost had a leak, preventing your car from boosting to specification).
After fitting a new DV you can see from the values obtained during the road test following repair (Fig.2) that the actual boost (red channel) pretty much traces the desired boost (green channel), recapturing the our 400 mbar of lost boost and getting our performance back!
FYI:
- Blue channel is accelerator pedal position so you can see exactly when maximum driver demand is applied and how boost responds.
- Purple channel is duty control to the vacuum solenoid i.e. low = give me max boost
Hope this was helpful
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