new exhaust and poor running (idle adaptation faults)

[Johnny Danger]

Originally Posted by Dave928

so my '01 S w/ 95k miles just got a full Maxspeed Motorsports exhaust installed, with the 4 200 cell cats.

after i picked up the car it ran fine for the drive to work, but would barely idle when i got in the parking lot. idle swinging up and down +- 300 RPM, sounds very loud, exhaust tips black with soot.

drove it back to the shop and CEL came on. got to the shop and they checked the faults, and came up with Fuel Trim Adaptation faults.

so basically the engine can't adapt the fuel trims and it's running FULL rich (black tips).

they've tried moving the post-cat O2's around (exhaust has 4 O2 bungs on each side), but this should be front O2 related. i replaced the front O2 sensors with aftermarket ones about a year ago, so the shop is going to try factory O2s (another $500 ) on monday.

if anyone has any ideas... ?

Just so I understand you correctly, you're running both 200 cell pre-cats and 200 cell secondary cats ?

[Dave928]

Originally Posted by Johnny Danger

Just so I understand you correctly, you're running both 200 cell pre-cats and 200 cell secondary cats ?

yes. here's the link...

Porsche Boxster 986 NHP Performance Exhaust 2.7L/3.2L

Originally Posted by ohhh my

isn't idling the car for long periods of time really bad?

as long as the water pump and cooling fans are working, isn't going to hurt anything.

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was brainstorming with a friend earlier, it sounds like an exhaust leak at the manifold gaskets. when at idle it would draw air in, making the S1 O2 sensor think the engine is running lean, so the ECU adds fuel, making it run rich. then at cruise, the exhaust blows out thru the leak, not affecting idle fuel trims. EXCEPT, it's both sides.

so either there's a header leak on BOTH sides (seems unlikely) or the problem is upstream of the engine... ECU, MAF, or throttle body. the question is why one of those would crap out from just changing the exhaust...