Diagnosis And Testing: SRT4
During normal operation the SRT - 4 turbocharger will emit a very high frequency whistle at full boost 68.9 - 103.4 kPa (10 - 15 psi) during WOT acceleration.
During throttle tip-out, the surge valve will emit a light air "woosh" noise. If there is excessive NVH or other air leak/turbocharger noises, the intercooler plumbing or turbocharger control system may be compromised.
TO identify the source of the concern, check for Diagnostic Trouble Codes (DTCs) stored in PCM memory. If any DTCs are present, refer to the appropriate Powertrain ELECTRICAL DIAGNOSTICS Information.
If there are no DTCs stored, use the following chart.
| CONDITION | POSSIBLE CAUSES | CORRECTION |
|---|---|---|
| UNDERBOOST - 20.6 - 27.5 kPa and turbocharger lag at WOT with some air leak noise OVERBOOST - 103.4 kPa (10 psi) or more even at part throttle (could be as high as 137.8 kPa (20 psi) or more). A "Fluttering" noise can be heard during overboost. CAUTION: Engine damage can result from prolonged Overboost. |
Waste Gate control hose plumbing compromised/disconnected | Refer to (Refer to EXHAUST SYSTEM/TURBOCHARGER SYSTEM/CHARGE AIR COOLER AND PLUMBING - INSTALLATION) |
| UNDERBOOST - 27.5 - 62 kPa (4 - 9 psi) @ WOT with "horse laugh" on throttle tip-out. | Surge valve control hose plumbing compromised. | Repair plumbing (Refer to EXHAUST SYSTEM/TURBOCHARGER SYSTEM/CHARGE AIR COOLER AND PLUMBING - INSTALLATION) . |
| NORMAL BOOST - but turbocharger lag and "horse laugh" noise on throttle tip-out. | Surge valve scroll and vacuum feeds reversed | Reverse vacuum lines (Refer to EXHAUST SYSTEM/TURBOCHARGER SYSTEM/SOLENOID - INSTALLATION) |
| UNDERBOOST - 0-20.6 kPa (0-3 psi) a WOT with loud air leak noise outside vehicle. Turbocharger may emit a "howling" noise. | Intercoooler plumbing hose disconnected | Inspect plumbing and install (Refer to EXHAUST SYSTEM/TURBOCHARGER SYSTEM/CHARGE AIR COOLER AND PLUMBING - INSTALLATION) |
| Very rough idle | TIP/MAP sensor hoses connected improperly or TIP disconnected | Inspect hoses (Refer to EXHAUST SYSTEM/TURBOCHARGER SYSTEM/LINES AND HOSES - INSTALLATION) |