1995 Mercedes C220 P0170 Code: Fixed Crimped Fuel Injector Wire, Now Experiencing Erratic RPMs - How to Fix?
I own a 1995 Mercedes-Benz C220 with a persistent P0170 fault code. After diagnosing and repairing a crimped fuel injector wire, I'm now experiencing erratic engine RPMs—especially at idle. The RPMs will spike unexpectedly even when the brake is applied, and after stopping for traffic, the car refuses to accelerate initially, though it eventually responds. I've confirmed the fuel injector wiring issue was resolved, but this new behavior persists. What could be causing these irregularities? Is there a deeper system issue or another component that needs attention? Any guidance on diagnosing or fixing this would be greatly appreciated.
P0170 indicates an oxygen sensor fuel trim malfunction, typically caused by intake air leaks. A smoke test is recommended to identify any leaks in the intake system. The throttle body seal, being rubber-based and flexible, can degrade or develop leaks over time—this may be a contributing factor. Additionally, crimped fuel injector wires are indeed a known issue on Mercedes-Benz vehicles from the 1990s, so your repair was appropriate, but the persistent RPM issues suggest further investigation into the intake system or throttle body.