why so rich?
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Joined: 10-01-16
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From: Butler, PA
why so rich?
2008 HHR SS running very rich, -100% LTF and stench out pipe. After driving a day like this it finally sooted up the O2 sensor and threw a slow response O2 code. All the vacuum lines appear intact but I don't know which one would directly control fuel pressure? the wiring to the fuel pressure regulator looks good and when disconnected the reduced power light shows so the circuit is good and it runs fine on initial start up in open loop while the O2 sensors warm up. What could cause over fuel and not show a DTC? Thank you for any ideas.
2008 HHR SS running very rich, -100% LTF and stench out pipe. After driving a day like this it finally sooted up the O2 sensor and threw a slow response O2 code. All the vacuum lines appear intact but I don't know which one would directly control fuel pressure? the wiring to the fuel pressure regulator looks good and when disconnected the reduced power light shows so the circuit is good and it runs fine on initial start up in open loop while the O2 sensors warm up. What could cause over fuel and not show a DTC? Thank you for any ideas.
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Joined: 10-01-16
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From: Butler, PA
No tune, have HP tuners but haven't unlocked, only scanning for now. Noticed a tank of gas went too quickly on a short trip and idle stated surging and also the exhaust stench. Drove to work and back and finally code set for the O2 sensor which is probably just soot. The fact that it idles OK on initial cold start up leads me away from a "stuck injector". Something is causing the over fuel and the ECM can't correct in closed loop but why no other codes? Thanks for asking, I'm technologically challenged and struggling to keep up.
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From: Butler, PA
OK, I'm at work and will try tonight. Will anything happen when the MAF is disconnected to pinpoint the primary O2? I don't have an issue changing the O2 sensor but wanted to be fairly certain, somewhere I read these wide bands were warrantied for 100,000 miles? I will post progress.
if it starts running better and not so rich the problem is the maf or maf wiring related. If nothing changes that direct you to the o2 sensor and wiring. The 100k "warranty" is meh the sensors are less than $100 on amazon
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Joined: 10-01-16
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From: Butler, PA
Follow up
Bought a Bosch O2 sensor from Rock Auto $75.98 to the door and put it on today, problem solved. Thanks to the help from here, ease of change out, and relative low cost it was one of the nicest repairs. 
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