PetroleumJunkie412
Unofficially Missing
⭐Supporting Member
TRS Event Participant
TRS 20th Anniversary
- Joined
- Oct 31, 2018
- Messages
- 8,206
- Points
- 601
- City
- Dirtman's Basement
- State - Country
- PA - USA
- Vehicle Year
- 1988
- Transmission
- Manual
- My credo
- Let's see Paul Allen's Ranger.
When is the last time you plugged a scan tool into your truck?Right. But the problem arises when that air straight from the enigne bay, passes through the PCV and enters the intake manifold behind the Throttle body. That air straight from the engine bay didn't pass through the MAF. Any air that enters the combustion chamber has to pass through the MAF, or it is what is called unmetered air. The computer knows it's there via the o2 sensors, but doesn't know where it came from. So it is technically a vacuum leak. if it doesn't make it run bad, it'll give you lean codes. The computer has the freedom to richen the mixture a little. Once it does that, if the o2 sensors still detect too much oxygen in the exhaust, you get the CEL.

