Diesel Power Loss? Check Intake Manifold Symptoms

Had a similar issue with my 2016 Chevy Silverado diesel, sounds exactly like what you're describing. Some experience working on diesels, but this one needed professional help. The manifold pressure was totally off due to a scorched intake manifold, causing vacuum leaks around the gaskets. Symptoms matched yours, rough idle, power loss, and that nasty exhaust smell. My advice: Get those error codes read first, Check for black residue around manifold edges, Listen for hissing sounds near the intake (indicates gasket leak) The repair involved replacing the intake manifold assembly and all gaskets. Set me back about 1180 for parts and labor, but fixed all issues completely. What's your mileage and maintenance history? Also, does the engine noise change when you rev it? These details would help confirm if you're dealing with the same problem. Better catch this early, manifold issues can damage other engine components if left unchecked.

Thanks for the feedback. I'm at 83533 KM with regular maintenance up to date. The engine noise definitely changes with revs, more of a stuttering sound above 2000 RPM. There's also a distinct whistling sound from the engine bay that wasn't there before. Just checked around the manifold edges and found some dark residue on the passenger side. Looks like a vacuum leak might be the culprit causing my engine misfire and performance issues. Going to get those codes read tomorrow and have a pro take a look. Rather sort it now than risk more engine damage. Getting serious deja vu from your Silverado story, sounds identical to what I'm experiencing.

Yeah, those symptoms are exactly what led to my manifold replacement. That whistling sound you're describing, classic sign of a vacuum leak, plus the dark residue in the same spot I found mine confirms it even more. The engine misfire and stuttering above 2000 RPM is textbook for failing manifold gaskets. My manifold pressure readings were way off before the repair, causing similar performance issues. After finding those exact symptoms, I didn't want to risk more engine damage either. Quick heads up, when they fixed mine, they discovered the gasket leak had affected the surrounding sensors too. Might want to have them check those while they're in there. My repair ended up needing new sensors along with the manifold work, but the improved engine performance was worth every penny. Keep us posted on those error codes. If they match what I got (P0299 and P0172), you're definitely looking at the same manifold issue I dealt with. The repair completely solved my engine performance problems and that annoying exhaust smell disappeared too.

Thanks again for the details. That P0299 code just came back from the scan, definitely points to the manifold issue like your case. Got the whistling noise recorded on my phone to show the mechanic tomorrow. The stuttering's gotten worse today, especially during acceleration. Really glad I caught this early before it caused more engine damage. The quote I got was pretty close to what you paid, around 1200 for the full repair including new sensors. You were spot on about the vacuum leak and gasket failure. All the symptoms match up perfectly, the engine misfire, dark residue, and that distinct whistling. The poor engine performance and rough idle make so much more sense now. Going to drop it off first thing tomorrow. Don't want to risk any more damage to the engine components. Will update the thread once it's fixed in case anyone else runs into similar manifold problems with these diesels.