DIY Guides › Electrical
A leaking MAP vacuum line causes bad readings and poor running on Renix rigs.
When to use this guide: 1987 to 1990 XJ with hesitation, rough running, or vacuum line failure.
On a Renix XJ, the small rubber elbow at the throttle body that connects to the MAP sensor hardens and cracks with age. When it leaks, the ECU gets a false vacuum reading and the engine runs lean, hesitation, rough idle, and drivability issues that look like sensor problems. The fix is a short piece of vacuum hose. Check this elbow before you replace any sensors.
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