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comanche · 03-18-2010, 04:41 PM

Someone correct me if I'm wrong.... maybe a major exhaust leak?

If there was a major exhaust leak after the engine, before the O2 sensor...
-Oxygen sensor would see much a much leaner mixture... since there would be a greater percentage of oxygen vs hydrocarbons...
-PCM will throw more fuel at the engine to make the mixture correct.... giving you those fuel trim numbers... and causing the car to run quite rich... but the car would think it was still running okay...

Anybody else think this might make sense?
Bad exhaust manifold gasket, or crack in manifold, or hole in exhaust?

Edit: BTW, you are going to kill the converter if you keep driving it this way...

03-18-2010, 04:41 PM	#20
comanche V.I.P. Member Join Date: Jul 2004 Location: Kalamazoo, MI Posts: 477	Someone correct me if I'm wrong.... maybe a major exhaust leak? If there was a major exhaust leak after the engine, before the O2 sensor... -Oxygen sensor would see much a much leaner mixture... since there would be a greater percentage of oxygen vs hydrocarbons... -PCM will throw more fuel at the engine to make the mixture correct.... giving you those fuel trim numbers... and causing the car to run quite rich... but the car would think it was still running okay... Anybody else think this might make sense? Bad exhaust manifold gasket, or crack in manifold, or hole in exhaust? Edit: BTW, you are going to kill the converter if you keep driving it this way...