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 Diagnostic Information.

If there are no DTCs stored, use the following chart.

CONDITION	POSSIBLE CAUSES	CORRECTION
UNDERBOOST - 20.6 - 27.5 kPa (2.9 - 3.9 psi) 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 11 - 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 11 - 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 11 - 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 11 - 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 11 - EXHAUST SYSTEM/TURBOCHARGER SYSTEM/LINES AND HOSES - INSTALLATION)