What causes a cylinder to run rich?
A vehicle’s fuel mixture refers to the ratio of fuel and air in the combustion process. When you have too much fuel and not enough air, your car is considered to be running “rich”.
What are the symptoms of low compression?
If you experience compression loss in one cylinder of the engine, it can cause misfiring and poor vehicle performance. A decrease in power output is a sign of worn-out internal parts. Sometimes, an engine misfire code may indicate compression loss, but first, check the ignition and fuel for problems.
Can a bad o2 sensor cause low compression?
A bad oxygen sensor will not cause low compression. Compression readings are an indication of the mechanical condition of the engine. Low compression indicates valves that are not sealing or piston rings that are not sealing.
What should the RPM be on a compression test?
Just make sure your compression tester is fully seated and with a good O-ring, 160 is kinda low. When all back together after the dry and wet compression tests, with a scan tool, unplug a coil pack harness one at a time and record the RPM drop for each cylinder.
What kind of fuel trim is running rich?
Okay, next issue… my car is running a little bit rich. Scanning it and reading about -8% LT when idling. When at around 25% throttle and 50kpa MAP LT fuel trim is just -1%. Pressing the throttle a little bit more and at higher MAP I get -4% to -8%. Values are not that much off so the check engine lights is not on and no DTC thrown.
How can I tell if my fuel trim is bad?
When all back together after the dry and wet compression tests, with a scan tool, unplug a coil pack harness one at a time and record the RPM drop for each cylinder. Hopefully we can rule out a bad or weak cylinder.
What happens when a cylinder is misfired in a car?
One of the worst culprits, a cylinder misfire, can cause a host of problems starting with your catalytic convertor. When a cylinder misfires, it can cause a cylinder’s worth of hot, unburnt to fuel enter the catalytic converter, melt the ceramic material inside.