What people keep running into with engine troubleshooting
Complaints tagged engine troubleshooting, each raised by more than one person. One-off posts are not included.
28 recurring problems · 609 people · 7 forums we read
Raised more than once
Most people first.
- 4Can a vacuum leak cause multiple cylinder misfires and a lean code?A vacuum leak lets unmetered air into the engine, causing a lean running condition like code P0171 and multiple cylinder misfires. This often happens alongside exhaust sputtering, and replacing basic ignition components like spark plugs and wires alone will not resolve the underlying air or fuel delivery issue.
- 4F150 Ecoboost misfire at idle but fine under accelerationThe engine misses noticeably on cold starts and low RPMs—sometimes stalling when coming to a stop—but has no issues during acceleration or highway cruising. Because the misfire counts are often too low to trigger a check engine light, identifying the problem requires looking at average cylinder acceleration to find the specific failing cylinder. Without thorough diagnostic testing, shops may just throw parts at the problem, quoting around $4,000 for camshaft and timing chain replacements.
- 3Cylinder misfire and white smoke from exhaustAn engine misfire persisting on the same cylinder despite replacing spark plugs and checking coils, combined with white exhaust smoke, typically indicates coolant entering the combustion chamber. This can foul the spark plug and lead to ongoing misfires and smoke.
- 3Heavy exhaust smoke and diesel smell on cold startA cold engine can produce heavy smoke and a strong diesel smell that becomes highly visible in the mirrors when revving or driving the first few meters. The smoke is minimal at idle and stops once the engine warms up, but the experience does not feel normal. This heavy white smoke on startup leaves owners questioning if their vehicle or lawnmower is safe to operate.
- 3Weird engine noise after clutch replacementThe clutch disc may have been installed backward, causing its back side to hit the flywheel bolts. This creates an awful noise when starting and prevents the engine from running smoothly, leaving drivers afraid to keep the car running for fear of further damage.
- 2Why is my car running rich and smoking after sitting for years?Vehicles left sitting for extended periods often suffer from degraded fuel, stuck injectors, or saturated components that cause them to consume excessive fuel and produce heavy smoke upon startup and throttle. This severe richness creates a strong fuel odor and prevents normal driving operation.
- 2Why does my leaf blower start for 3 seconds and die?Small engines and leaf blowers sometimes start briefly for a few seconds before turning off, and can produce smoke when they shut down. Other times, equipment may sit unused for a few days without starting at all, or only fire up on the second attempt after multiple tries.
- 2Why does oil pressure drop when the engine is hot?Worn engine bearings cause perfect oil pressure during a cold start to plummet to near zero once the engine heats up or sits in neutral. Cleaning the oil pickup screen and replacing the O-ring may improve the initial cold pressure, but it will not prevent the pressure from eventually dropping back to zero as the engine reaches operating temperature.
Comes up alongside
Topics that keep appearing on the same problems — not topics with similar names.