Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
WASTEGATE-Diagnosis And Testing
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 "whoosh" 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 Engine ELECTRICAL DIAGNOSTICS article .
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 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. See 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 INSTALLATION ). |
| UNDERBOOST - 0-20.6 kPa (0-3 psi) a WOT with loud air leak noise outside vehicle. Turbocharger may emit a "howling" noise. | Intercooler plumbing hose disconnected | Inspect plumbing and install. See INSTALLATION . |
| Very rough idle | TIP/MAP sensor hoses connected improperly or TIP disconnected | Inspect hoses. See INSTALLATION . |
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.