1128 and 1130 still... Idle is HORRIBLE

[Topless]

Intake and exhaust leaks need to be fixed and your idle will smooth out. The codes listed are common for intake or exhaust leaks. The car is running lean.

[shadrach74]

Originally Posted by Topless

Intake and exhaust leaks need to be fixed and your idle will smooth out. The codes listed are common for intake or exhaust leaks. The car is running lean.

How does the ECU read an exhaust leak aft of the post cat O2 sensor? It seems to me that anything from that point back makes no difference to the ECU. If id does,please help me understand how leaky bypass pipes cause idling issues?

[BYprodriver]

Originally Posted by shadrach74

How does the ECU read an exhaust leak aft of the post cat O2 sensor? It seems to me that anything from that point back makes no difference to the ECU. If id does,please help me understand how leaky bypass pipes cause idling issues?

The ECU reads that the engine is running lean beyond the ECU's capability to compenstate. Exhaust leaks is 1 of many possible causes.

[shadrach74]

Originally Posted by BYprodriver

The ECU reads that the engine is running lean beyond the ECU's capability to compenstate. Exhaust leaks is 1 of many possible causes.

How does the engine read a "lean run" condition from a leak aft of the metered section of exhaust? There is no O2 sensor on the mid-pipe/secondary cat. The only leak the ECU would have the ability to detect would be between where the manifold meets the exhaust port or an actual hole in the manifold/header. I cannot understand your assertion that the O2 sensors are capable of sensing anything downstream of their positions...

[Topless]

Originally Posted by shadrach74

How does the engine read a "lean run" condition from a leak aft of the metered section of exhaust? There is no O2 sensor on the mid-pipe/secondary cat. The only leak the ECU would have the ability to detect would be between where the manifold meets the exhaust port or an actual hole in the manifold/header. I cannot understand your assertion that the O2 sensors are capable of sensing anything downstream of their positions...

Shad,
We don't really know where his exhaust leaks are for certain. We have not seen them and he "may" have more exhaust leaks than he is currently aware of. We do know that an intake or nearby exhaust leak will foul the sensor readings and contribute to rough idle. Simple process of elimination. Fix the obvious thing you are certain is wrong and move on to the next. This is always more effective than changing out perfectly good parts.

[shadrach74]

Originally Posted by Topless

Shad,
We don't really know where his exhaust leaks are for certain. We have not seen them and he "may" have more exhaust leaks than he is currently aware of. We do know that an intake or nearby exhaust leak will foul the sensor readings and contribute to rough idle. Simple process of elimination. Fix the obvious thing you are certain is wrong and move on to the next. This is always more effective than changing out perfectly good parts.

I see what you're saying, but he made it pretty clear that the leaks were around the bypass pipes. I'm not advocating changing out parts, I agree that the intake is the one of the places I'd look if I had a rough idle, slip joints at the mid-pipes...not so much.