Sierra Engine Performance Loss Due to Faulty Manifold

Previously dealt with similar symptoms on a 2007 Canyon with the 3.7L engine. The MAP sensor and intake manifold were both compromised, causing serious vacuum leaks. The engine performance issues matched exactly, sluggish acceleration, excessive fuel consumption, and illuminated check engine light. The diagnosis revealed multiple issues: Cracked intake manifold gasket allowing air leaks, Failed MAP sensor giving incorrect readings, Vacuum lines deteriorated from age This combination of problems required complete intake manifold removal to access and replace the faulty car sensors. The repair was relatively serious since the intake manifold had to be fully removed and resealed. Labor intensive but necessary to restore proper engine performance. For your Sierra symptoms, recommend: 1. Full diagnostic scan for vacuum leak detection 2. MAP sensor testing and validation 3. Visual inspection of intake manifold gaskets 4. Smoke test to identify any additional leaks This is not a quick fix but addressing it promptly prevents further engine damage. The sensor replacement itself is straightforward, but accessing it through the intake manifold system requires experienced hands.

Thanks for sharing those details about the MAP sensor and manifold issues. The symptoms you described match what I experienced with my GMC. Glad I caught it early. The repair sorted out my engine performance problems completely. Did the total repair cost include both parts and labor? Also curious if you had any recurring manifold pressure issues since the fix? My mechanic mentioned these car sensors sometimes need recalibration after a few months.

Thanks for the follow-up. The MAP sensor repair job turned out great and fully resolved the vacuum leakage that was causing the poor engine performance. The total came to 235 Euro, which included both the sensor replacement and fixing the intake manifold seal. Since the repair six months ago, engine performance has remained consistently strong with no need for MAP sensor recalibration. The car sensors are working exactly as they should, maintaining proper pressure readings and optimal fuel efficiency. The key was finding and addressing all vacuum leak points during the initial repair. A thorough mechanic will pressure test the entire intake manifold system to ensure no small leaks remain. This comprehensive approach prevents recurring issues with manifold pressure readings. My suggestion would be to monitor your fuel consumption and acceleration response over the next few weeks. This will confirm the repair is holding up well. Modern engine management systems are quite good at alerting us early if the MAP sensor starts drifting out of calibration.

I took my Sierra to a reliable mechanic last week after getting great advice here about MAP sensor issues. The diagnostic confirmed what many suggested, a faulty manifold pressure sensor combined with minor vacuum leaks was causing my engine performance problems. The repair process went smoothly: Complete manifold sensor replacement, New gaskets and vacuum lines, Full system pressure testing, ECU reset and calibration Total repair cost was 780 Euro but worth every cent. The engine performance difference is remarkable, much better acceleration and fuel economy already. The mechanic was transparent about the work needed and even showed me the old failed sensor. No more check engine light and the sluggish response is completely gone. Really glad I addressed this early before it could cause more serious engine problems. This shop definitely earned my trust with their thorough approach to fixing the pressure sensor issues.