Loss of Power
To clarify, this page is targetted at scenarios where your vehicle loses power under load where the engine seems to "fall on its face". This can be either partial (losing acceleration past a certain RPM) or total (utter refusal to rev past a certain RPM). If your motor is cutting out completely, see our page on stalling.
Turbo Vehicle Power Loss
This issue is most common on the turbo applications of our platform for two reasons. First is the occurance of boost leaks, and second is the "blowout" of spark / ignition.
Boost Leaks
For diagnostics of boost leaks, please check out our intake maintenance page
Spark "Blowout"
While the spark doesn't actually blow out, the increased air density and pressure in the cylinder is more resistant to electricity, which can lead to worn spark plugs failing to jump the gap under boost.
Remove and investigate your spark plugs. If they are heavily worn, replace them. You can also attempt to gap them down if you aren't able to immediately replace them, but if you're pulling your upper plenum off to access the rear plugs, it's best to replace them while you're in there.
It may also be prudent to replace your spark plug wires, as worn wires can reduce the available current to the plugs, which can exacerbate this phenominon.
General Vehicle Power Loss
If the above two troubleshooting steps didn't fix your turbo vehicle, or if you have a naturally aspirated vehicle, move on to this section.
Air-Fuel Ratio
Your ECU is responsible for calculating your air-fuel ratio based on the input from the mass airflow sensor. A miscalculation (or inability to meet the demand) can be a result of several things including a failed MAF, a failed ECU, or insufficient / clogged or damaged fueling.
This section is a stub, it will be expanded in future updates.